CN111633955B

CN111633955B - Flexible forming device and method for thermoplastic material

Info

Publication number: CN111633955B
Application number: CN202010434008.4A
Authority: CN
Inventors: 张琦; 罗伟; 徐宏图; 韩宾; 段文杰; 鱼在池
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2020-05-21
Filing date: 2020-05-21
Publication date: 2021-05-07
Anticipated expiration: 2040-05-21
Also published as: CN111633955A

Abstract

A thermoplastic material flexible forming device comprises a multi-point flexible mold, a locking device and a flexible blank pressing system, wherein the multi-point flexible mold is embedded in the locking device, and the flexible blank pressing system is arranged on the locking device; the multipoint flexible mold comprises a square frame formed by connecting four pressing plates, high-temperature-resistant rubber for sealing is arranged in the square frame, a plurality of groups of square lattices formed by inserting carbon fiber yarns are arranged in the high-temperature-resistant rubber for sealing, basic unit bodies are arranged in the square lattices, and the ends of the carbon fiber yarns are fixed on the pressing plates by wire clamps; the locking device comprises an outer frame, a locking hydraulic cylinder is fixed on the inner side of the outer frame, and an output shaft is in contact with the pressure plate; the flexible edge pressing system comprises a stand column fixed on the outer frame, an edge pressing hydraulic cylinder is fixed on the stand column, a piston of the flexible edge pressing hydraulic cylinder is attached to a plate through an edge pressing ring, the plate is placed on a pressing plate, and an oil storage ring groove is embedded in the pressing plate; the invention can accurately control the forming process in real time and has the advantages of low cost of mass production, short period and good flexibility.

Description

Flexible forming device and method for thermoplastic material

Technical Field

The invention relates to the technical field of flexible forming, in particular to a device and a method for forming thermoplastic materials flexibly.

Background

Plastic parts are widely used in daily life, and the traditional plastic processing and forming method mainly comprises extrusion, injection molding, calendering, blow molding, mould pressing, plastic sucking, thermal forming and the like, but the defects of high production cost of small batches, high trial production cost of samples, long period, poor flexibility and the like are generally existed.

Flexible manufacturing is a development trend of manufacturing industry, wherein a 'dieless multipoint forming technology' is an advanced manufacturing technology integrating a flexible forming technology and a computer technology, and is a three-dimensional curved surface digital forming technology of a plate.

The multi-point forming technology is applied to the flexible forming of thermoplastic materials, is a novel forming technology, has the advantages of low cost, high flexibility, short forming period, high precision and the like, and is expected to be applied to the fields of medical treatment, automobiles, aerospace, mechanical manufacturing and the like.

Disclosure of Invention

In order to overcome the disadvantages of the prior art, the present invention provides a flexible forming apparatus and method for thermoplastic materials, which has the advantages of low mass production cost, low trial production cost, short cycle time and good flexibility, and can be widely applied to flexible processing of thermoplastic materials (such as PEEK, ABS, etc.).

In order to achieve the purpose, the invention adopts the technical scheme that:

a thermoplastic material flexible forming device comprises a multi-point flexible mold, a locking device and a flexible blank pressing system, wherein the multi-point flexible mold is embedded in the locking device, and the flexible blank pressing system is arranged on the locking device;

the multipoint flexible mold comprises four pressing plates 3, wherein the four pressing plates 3 are respectively a left pressing plate 3-1, a right pressing plate 3-2, an upper pressing plate 3-3 and a lower pressing plate 3-4, the four pressing plates form a square frame, high-temperature-resistant rubber 14 for sealing is arranged in the square frame, a plurality of groups of square lattices are formed by inserting carbon fiber yarns 17 in the high-temperature-resistant rubber 14 for sealing, basic unit bodies 4 are arranged in the square lattices, and the ends of the carbon fiber yarns 17 are fixed on the pressing plates 3 by wire clamps 18;

the locking device comprises an outer frame 9, a locking hydraulic cylinder 16 is fixed on the inner side surface of the outer frame 9, an output shaft of the locking hydraulic cylinder 16 is in contact with the outer side of the pressure plate 3, the locking hydraulic cylinder 16 is controlled by a locking hydraulic control loop, and an L-shaped plate 10 is fixed on the outer side surface of the outer frame 9;

flexible blank pressing system include

stand

11, 11 lower extremes of stand are fixed on

frame

9, 11 upper ends of stand are fixed with blank pressing pneumatic cylinder 12, blank pressing pneumatic cylinder 12's pneumatic cylinder piston 13 and the laminating of 1 up end of blank holder, 1 lower terminal surface links firmly blank pressing flange 5 of blank holder, 5 cambered surfaces of blank pressing flange and the laminating of panel 2, panel 2 is placed on clamp plate 3, the embedded oil storage annular 6 that has on the clamp plate 3, the 6 medial surfaces of oil storage annular are laminated with sealed high temperature resistant rubber 14, blank pressing pneumatic cylinder 12 is by blank pressing hydraulic control return circuit control.

The main body shapes of the left pressing plate 3-1, the right pressing plate 3-2 and the upper pressing plate 3-3 are cuboids, the section of the lower pressing plate 3-4 is in a convex shape, the four pressing plates have the same length direction size, and the two end faces are flush; in an initial state, the four pressing plates are fixedly connected together through the locking bolts 19 to form a square frame, a series of small through holes are regularly arranged on the outer side surface of the square frame, the carbon fiber yarns 17 penetrate through the through holes, and the inner side surface of the square frame is attached to the high-temperature-resistant rubber 14 for sealing to form a sealed inner cavity.

The carbon fiber filaments 17 are high-strength carbon fiber filaments with the diameter smaller than 1mm, and are divided into two groups, namely upper and lower pressing plates 17-1 and left and right pressing plates 17-2 according to the distribution direction, the upper and lower pressing plates penetrate through the upper pressing plate and the lower pressing plate through the carbon fiber filaments 17-1, the left and right pressing plates penetrate through the left pressing plate and the right pressing plate through the carbon fiber filaments 17-2, the left and right pressing plates penetrate through the right pressing plate and the left and right pressing plates continuously and repeatedly penetrate between the left and right pressing plates or the upper and lower pressing plates, a plurality of groups of square grids are formed by penetrating in the high-temperature-resistant rubber 14 for sealing, the two groups of carbon fiber filaments penetrating up and down and left and right are in tangential contact with each other at the.

The basic unit body 4 is a cuboid with a rectangular cross section, a circular through hole is formed in the center of the cross section, the side length of the cuboid is smaller than 5mm, a pressure sensor is mounted on the end face, close to one side of the plate 2, of the basic unit body 4 and used for monitoring the pressure in the cavity 7 and the axial pressure born by each basic unit body 4, and the basic unit body 4 is mounted in a square grid formed by carbon fiber yarns 17 and can move along the axis of the through hole in the square grid.

The end, close to the plate 2, of the high-temperature-resistant rubber 14 for sealing is of a 'return' hollow structure, the end, far away from the plate 2, of the high-temperature-resistant rubber is of a bell mouth shape, and small through holes allowing the carbon fiber yarns 17 to penetrate through are formed in the side face of the high-temperature-resistant rubber.

The outer frame 9 is in a hollow hat shape, one end close to the plate 2 is a hat brim, and the other end is in a 'return' shape; the number of the locking hydraulic cylinders 16 is four, the output shaft of the first locking hydraulic cylinder 16-1 is in contact with the left pressing plate 3-1, the output shaft of the second locking hydraulic cylinder 16-2 is in contact with the right pressing plate 3-2, the output shaft of the third locking hydraulic cylinder 16-3 is in contact with the upper pressing plate 3-3, the output shaft of the fourth locking hydraulic cylinder 16-4 is in contact with the lower pressing plate 3-4, and the output shafts of the four locking hydraulic cylinders are all located in the center of the corresponding pressing plate 3.

The pressing plate 3 is provided with a rectangular groove at one side close to the plate 2, the rectangular grooves of the four pressing plates are connected to form an annular groove, and an oil storage annular groove 6 is arranged in the annular groove.

The upright columns 11 are inverted L-shaped and are respectively arranged at the left side, the right side and the center of the rear side of the end surface of the brim of the outer frame 9, and the left and right upright columns are symmetrical about the central upright column of the rear side.

The lower end of the hydraulic cylinder piston 13 is a rectangular block, and the lower end face of the rectangular block is attached to the upper end face of the blank holder 1.

The blank holder 1 be square annular, the up end be the plane, the up end is laminated with pneumatic cylinder piston 13 lower extreme face, lower extreme face links firmly blank pressing flange 5, its cross-sectional profile is the arc, blank

pressing flange

5 and 2 up end laminating of panel.

The oil storage ring groove 6 is square annular, the cross section of the oil storage ring groove is concave, the middle concave part is arc-shaped, the radian of the middle concave part is slightly smaller than that of the blank pressing flange 5, the oil storage ring groove 6 is arranged in an end surface groove of the pressing plate 3 close to one side of the plate 2, and the groove of the oil storage ring groove 6 is coincided with the arc symmetry plane of the blank pressing flange 5.

The forming method based on the thermoplastic material flexible forming device comprises the following steps:

the first step is as follows: aiming at the three-dimensional curved surface to be formed, acquiring the three-dimensional information of the part to be formed by a reverse engineering means, and calculating the height of each basic unit body 4 to be adjusted by using calculation software;

the second step is that: firstly, placing high-temperature-resistant rubber 14 for sealing on the upper top surface of a lower pressing plate 3-4, installing a left pressing plate 3-1 and a right pressing plate 3-2 on the lower pressing plate 3-4, fixing the upper pressing plate 3-3 on the left pressing plate 3-1 and the right pressing plate 3-2, forming a square frame by the four pressing plates, enabling the high-temperature-resistant rubber 14 for sealing to be in an original non-compression state, enabling an inner frame formed by the four pressing plates to be attached to the outer frame surface of the high-temperature-resistant rubber 14 for sealing, and enabling the relative positions of the four pressing plates to be fixed through connection of locking bolts 19; the carbon fiber yarns 17 are inserted between the left pressing plate 3-1 and the right pressing plate 3-2, and between the upper pressing plate 3-3 and the lower pressing plate 3-4, and two ends of the carbon fiber yarns are fixed on the pressing plate 3 by wire clamps 18; the carbon fiber yarns form a plurality of groups of square lattices, the basic unit bodies 4 are inserted into the square lattices, and all the basic unit bodies 4 are flush at one side far away from the plate 2;

the third step: adjusting the shape of the mould, namely automatically adjusting the hollow basic unit body 4 to a corresponding position from one side close to the plate 2 by using a shape adjusting device, so that the side, provided with the sensor, of the hollow basic unit body 4 group is wrapped with a curved surface to be formed, and a cavity 7 with a specific shape is formed; the four locking hydraulic cylinders 16 are filled with liquid with the same pressure by using a locking linkage hydraulic control loop, so that the four pressing plates 3 move towards the middle and compress the high-temperature-resistant rubber 14 for sealing, and the adjusted basic unit 4 keeps the shape; fixing the multi-point flexible mould on a forming test bed through an L-shaped plate 10;

the fourth step: locking the mould, namely installing the oil storage ring groove 6 on a multi-point flexible mould, installing the adjusted multi-point flexible mould on a locking device, loosening a wire clamp 18 of the carbon fiber wire on one side, filling liquid with the same pressure into four locking hydraulic cylinders 16 by using a locking linkage hydraulic control loop, and moving the four pressing plates 3 towards the middle and pressing the high-temperature-resistant rubber 14 for sealing, so that the basic unit 4 group is locked under the indirect action of the pressing plates 3;

the fifth step: putting the plate 2 into the oil storage ring groove 6, and pouring high-temperature-resistant sealing oil into the oil storage ring groove to enable the oil storage ring groove to be in contact with the plate 2 during high-temperature edge pressing to realize sealing; placing the plate 2 on a multi-point flexible mould with an adjusted profile, and attaching the plate to the upper end of the pressing plate 3, the upper end of the oil storage ring groove 6 and the upper end of the high-temperature-resistant rubber for sealing 14; putting the blank holder 1, attaching the blank holder flange 5 to the upper end of the plate 2, and simultaneously enabling the groove of the oil storage ring groove 6 to be superposed with the arc symmetrical surface of the blank holder flange 5; the pressure in the three side pressing hydraulic cylinders 12 is controlled to be consistent all the time by using a side pressing linkage hydraulic loop, and the hydraulic cylinder piston 13 is contacted with the upper end surface of the side pressing ring 1 by filling liquid;

and a sixth step: forming the plate, namely heating the plate 2 to raise the temperature of the plate to a formable temperature range; pumping air from a horn mouth of the high-temperature-resistant rubber 14 for sealing, keeping a certain negative pressure in a cavity 7 formed by adjusting a multi-point flexible mold close to one side of the plate 2, attaching the high-temperature plate 2 to the envelope surface of the basic unit body 4 group under the action of outside atmospheric pressure to complete the forming of the plate 2, and simultaneously performing closed-loop control and real-time adjustment on the negative pressure and the blank holder pressure in the cavity by monitoring the pressure born by each basic unit body 4 and the negative pressure value in the cavity 7; and cooling and maintaining the pressure after the forming is finished, releasing the pressure in the blank holder hydraulic cylinder 12, taking out the blank holder 1, taking out the formed piece and finishing the process.

When forming, each basic unit body 4 is applied with extra pressure to locally carry out non-isostatic forming, so that the formed piece has better quality.

The invention has the beneficial effects that:

1. the invention can accurately control the forming process in real time, and has high intellectualization, automation and flexibility;

2. the invention can be applied to the plate forming of any three-dimensional curved surface piece made of any thermoplastic material in principle, can also be applied to the plate forming of soft metal materials, and can effectively reduce the step effect during multipoint forming by adopting negative pressure forming;

3. the basic unit body can realize local non-isobaric forming, so that the forming quality is higher; the side length of the basic unit body can be adjusted at will and can be very small in principle, so that the continuity degree of the die surface enveloped by the multipoint die after shape adjustment is very good;

4. the invention adopts the flexible blank holder which is controlled by hydraulic pressure, and can control the blank holder force in real time in the forming process.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a sectional view taken along line a-a of fig. 1.

Fig. 3 is a cross-sectional view along line B-B of fig. 1.

Fig. 4 is an installation diagram of the basic unit body.

FIG. 5 is a structural diagram of a side of the multi-point flexible mold close to the sheet.

The left drawing in fig. 6 is a schematic view of the carbon fiber yarns for the upper platen and the lower platen, and the right drawing is a schematic view of the carbon fiber yarns for the left platen and the right platen.

Fig. 7 is a schematic structural view of the left press plate.

Fig. 8 is a schematic diagram of a lower pressing plate structure.

Fig. 9 is a schematic structural view of the upper platen.

FIG. 10 is a schematic view of a binder bead on a binder.

FIG. 11 is a schematic view of the oil storage ring groove.

FIG. 12 is a schematic view of the ring grooves formed on the end surface of the four pressing plates near one side of the plate.

Fig. 13 is a schematic view of the basic unit body forming a cavity by shaping.

Detailed Description

The invention is described in further detail below with reference to the figures and examples.

Referring to fig. 1 and 2, a thermoplastic material flexible forming device comprises a multi-point flexible mold, a locking device and a flexible edge pressing system, wherein the multi-point flexible mold is embedded in the locking device, and the flexible edge pressing system is installed on the locking device;

referring to fig. 3 and 4, the pressing plate 3 includes four pressing plates, namely a left pressing plate 3-1, a right pressing plate 3-2, an upper pressing plate 3-3 and a lower pressing plate 3-4; referring to fig. 7, the left pressing plate 3-1 and the right pressing plate 3-2 have the same structure, the main body of the left pressing plate 3-1 and the right pressing plate 3-2 are cuboid, a series of small through holes are regularly arranged on the front surface, carbon fiber yarns 17 penetrate through the through holes, holes matched with locking bolts 19 are arranged above the front surface and used for being fixedly connected with the upper pressing plate 3-3, a rectangular through groove is arranged at the lower end of the front surface and matched with a convex shoulder of the lower pressing plate 3-4, a rectangular groove is arranged on the end surface of the right side and used for placing an oil storage ring groove 6, and a bolt hole is arranged on the bottom surface and used; referring to fig. 8, the section of the lower pressing plate 3-4 is in a convex shape, a series of small through holes are regularly arranged in the front, carbon fiber yarns 17 penetrate through the through holes, a rectangular groove is formed in the right side face, an oil storage ring groove 6 is arranged in the groove, bolt holes are formed in two shoulders of the convex shape at the upper end and the lower end of the front, and the bolt holes are used for being fixedly connected with the left pressing plate 3-1 and the right pressing plate 3-2; referring to fig. 9, a series of small through holes are regularly arranged on the upper pressure plate 3-3, bolt holes are arranged on the front side and the rear side for the mutual fixed connection between the left pressure plate 3-1 and the right pressure plate 3-2, a rectangular groove is arranged on the end face on the right side, and an oil storage ring groove 6 is arranged in the groove; the four press plates have the same length direction size and the left end surface and the right end surface are flush. Referring to fig. 3 and 4, in an initial state, the pressing plate 3 is fixedly connected together through the locking bolt 19 to form a square frame, and the inner side surface of the square frame is attached to the high-temperature-resistant sealing rubber 14 to form a sealed inner cavity; referring to fig. 5 and 12, the four pressing plates 3 are connected to form a circular groove at one side close to the plate 2, and the rectangular groove is used for placing the oil storage circular groove 6.

Referring to fig. 2, 3 and 4, the section of the basic unit body 4 is a rectangular cuboid, a circular through hole is formed in the center of the section, the side length of the cuboid is less than 5mm, a pressure sensor is mounted on the end face, close to one side of the plate 2, of the basic unit body 4 and used for monitoring the pressure in the cavity 7 and the axial pressure born by each basic unit body 4, the basic unit body 4 is mounted in a square grid formed by carbon fiber yarns 17 and can move along the axis of the through hole in the square grid, the basic unit bodies 4 are separated by the carbon fiber yarns 17, and the motions of the basic unit bodies 4 are not interfered with each other.

Referring to fig. 1, 2, 3 and 4, one end of the high temperature resistant rubber 14 for sealing close to the plate 2 is of a 'return' hollow structure, the end far away from the plate 2 is of a bell mouth shape, a small hole matched with the carbon fiber yarn 17 is arranged on the side face, and the high temperature resistant rubber 14 for sealing can keep elasticity under long-term high temperature and can be repeatedly used; referring to fig. 5 and 12, the outer surface of the sealing high-temperature-resistant rubber 14 is bonded to the inner surface of the platen 3, and the inner surface of the sealing high-temperature-resistant rubber 14 is bonded to the carbon fiber yarn 17.

Referring to fig. 3, 4, 5 and 6, the carbon fiber filament 17 is a carbon fiber filament with a very small diameter (less than 1mm) and high strength, the upper and lower press plates penetrate through the upper press plate 3-3 by the carbon fiber filament 17-1, and the lower press plate 3-4 penetrates out; the left pressing plate and the right pressing plate penetrate through the left pressing plate 3-1 by using carbon fiber yarns 17-2, the right pressing plate 3-2 penetrates out, the upper pressing plate, the lower pressing plate or the left pressing plate and the right pressing plate are continuously inserted for multiple times according to an insertion path shown in figure 6, two groups of carbon fiber yarns are inserted into the high-temperature-resistant rubber 14 for sealing to form multiple groups of square grids, the two groups of carbon fiber yarns which are inserted up and down, left and right are in tangential contact at the square grids, the side length of each square grid is equal to that of the basic unit body 4, and the two ends of each; the basic unit bodies 4 penetrate through square grids formed by the carbon fiber yarns 17, the basic unit bodies 4 can move in the square grids along the axial direction of the basic unit bodies, the basic unit bodies 4 are separated through the carbon fiber yarns 17, and the movement of the basic unit bodies 4 is not interfered with each other; the line card 18 is used for locking the carbon fiber yarns 17 to prevent the carbon fiber yarns 17 from loosening.

Referring to fig. 2, 3, 4 and 5, the locking device comprises an outer frame 9, a locking hydraulic cylinder 16 is fixed on the inner side surface of the outer frame 9, an output shaft of the locking hydraulic cylinder 16 is in contact with the outer side of the pressure plate 3, the locking hydraulic cylinder 16 is controlled by a locking hydraulic control circuit, and an L-shaped plate 10 is fixed on the outer side surface of the outer frame 9.

Referring to fig. 1, 2 and 3, the outer frame 9 is in the shape of a hollow hat, one end of the outer frame close to the plate 2 is a hat brim, and the other end of the outer frame is in a shape of a square; referring to fig. 2 and 3, the locking hydraulic cylinders 16 are fixed on the inner side surface of the outer frame 9, wherein the output shaft of the first locking hydraulic cylinder 16-1 is in contact with the left press plate 3-1, the output shaft of the second locking hydraulic cylinder 16-2 is in contact with the right press plate 3-2, the output shaft of the third locking hydraulic cylinder 16-3 is in contact with the upper press plate 3-3, the output shaft of the fourth locking hydraulic cylinder 16-4 is in contact with the lower press plate 3-4, and the output shafts of the locking hydraulic cylinders are all located in the center of the corresponding press plate 3.

Referring to fig. 1 and 2, the flexible edge pressing system comprises a vertical column 11, the lower end of the vertical column 11 is fixed on an outer frame 9, an edge pressing hydraulic cylinder 12 is fixed at the upper end of the vertical column 11, a hydraulic cylinder piston 13 of the edge pressing hydraulic cylinder 12 is attached to the upper end face of an edge pressing ring 1, and three hydraulic cylinder pistons 13 perform piston movement in the edge pressing hydraulic cylinder 12; the lower end face of the blank holder 1 is fixedly connected with a blank holder flange 5, the cambered surface of the blank holder flange 5 is attached to a plate 2, the plate 2 is placed on a pressing plate 3, referring to fig. 5, an oil storage ring groove 6 is embedded in the pressing plate 3, the inner side face of the oil storage ring groove 6 is attached to high-temperature-resistant sealing rubber 14, and a blank holder hydraulic cylinder 12 is controlled by a blank holder hydraulic control loop.

Referring to fig. 1 and 2, the flexible edge pressing system is fixed on the end face of the "brim" of the outer frame 9 through three upright posts 11, the upright posts 11 are inverted "L" shapes and are respectively arranged at the left side, the right side and the center of the rear side of the end face of the "brim" of the outer frame 9, and the two upright posts at the left side and the right side are symmetrical about the central upright post at the rear side.

Referring to fig. 1 and 2, the edge pressing hydraulic cylinder 12 is fixed on the upper end plane of the upright post 11; the lower end of the hydraulic cylinder piston 13 is a rectangular block, and the lower end face of the rectangular block is attached to the upper end face of the blank holder 1.

Referring to fig. 2 and 10, the blank holder 1 is square and annular, the upper end face of the blank holder is a plane and is matched with the lower end face of the hydraulic cylinder piston 13, the lower end face of the blank holder is fixedly connected with the blank holder flange 5, the cross section of the blank holder flange 5 is arc-shaped, and the arc surface of the blank holder flange 5 is attached to the upper end face of the plate 2.

Referring to fig. 2, fig. 5 and fig. 11, oil storage ring groove 6 be square annular, the cross-section is "concave" shape, middle concave recess is the arc, its radian slightly is less than blank holder flange 5's radian, oil storage ring groove 6 is installed in the terminal surface inslot that clamp plate 3 is close to panel one side, the up end is close to the terminal surface parallel and level of panel 2 with clamp plate 3, and is close to the terminal surface parallel and level of panel 2 one side with sealed high temperature resistant rubber 14, oil storage ring groove 6 up end and panel 2 contact during shaping, annular medial surface and sealed high temperature resistant rubber 14 contact with, the lateral surface is laminated with clamp plate 3, the groove of oil storage ring groove 6 and the coincidence of the arc symmetrical plane of blank holder flange 5.

the first step is as follows: acquiring shape adjusting information, acquiring the three-dimensional information of the part to be formed by a reverse engineering means aiming at the three-dimensional curved surface to be formed, and calculating the height of each basic unit body 4 to be adjusted by using calculation software;

the second step is that: firstly, a multi-point flexible mould is assembled, referring to fig. 4, high temperature resistant rubber 14 for sealing is placed on the upper top surface of a lower pressing plate 3-4, the left side surface and the right side surface of the upper pressing plate are flush with the left side surface and the right side surface of a convex part of the lower pressing plate 3-4, a left pressing plate 3-1 and a right pressing plate 3-2 are arranged on the lower pressing plate 3-4, the upper pressing plate 3-3 is locked by a locking bolt 19 on the lower bottom surface of the lower pressing plate 3-4, the upper pressing plate 3-3 is fixed by a bolt hole on the outer side surface of the left pressing plate 3-1 and the right pressing plate 3-2 by the locking bolt 19, the upper top surface of the upper pressing plate 3-3 is flush with the upper end surfaces of the left pressing plate 3-1 and the right pressing plate 3-2, the four pressing plates form a square frame, at the moment, the high temperature resistant rubber 14 for, the relative positions of the four pressure plates are fixed by the connection of the locking bolts 19; referring to the path shown in fig. 6, a carbon fiber yarn 17 is inserted between a left pressing plate 3-1 and a right pressing plate 3-2, and between an upper pressing plate 3-3 and a lower pressing plate 3-4, one end of the carbon fiber yarn 17 is fixed on the outer side surface of one side pressing plate 3 by a wire clamp 18, the carbon fiber yarn 17 is tensioned, and then the other end of the carbon fiber yarn 17 is fixed on the outer side end surface of the opposite side pressing plate 3 by the wire clamp 18; referring to fig. 4, two groups of carbon fiber yarns form a plurality of groups of square lattices (vertical to the paper surface and in the paper surface), the two groups of carbon fiber yarns which are vertically and horizontally inserted are in tangential contact at the square lattices, the basic unit bodies 4 are inserted into the square lattices one by one from the lower pressing plate 3-4 to the upper pressing plate 3-3, and all the basic unit bodies 4 are flush at one side far away from the plate 2;

the third step: the mould is adjusted, referring to fig. 13, the hollow basic unit 4 is automatically adjusted to a corresponding position from one side close to the plate 2 by using an adjusting device, so that the side of the hollow basic unit 4 group with the sensor is wrapped with a curved surface to be formed, and a cavity 7 with a specific shape is formed; part of the locking bolts 19 of the fixed pressing plate 3 are taken down, the four locking hydraulic cylinders 16 are filled with liquid with the same pressure by using a locking linkage hydraulic control loop, so that the locking hydraulic cylinders 16 have certain pre-locking force, the four pressing plates 3 move towards the middle and compress the high-temperature-resistant rubber 14 for sealing, and the adjusted basic unit 4 keeps the shape; fixing the multi-point flexible mould on a forming test bed through an L-shaped plate 10;

the fourth step: locking the mould, referring to fig. 5, mounting the oil storage ring groove 6 on a multi-point flexible mould, and enabling two sides of the oil storage ring groove to be respectively contacted with the pressing plate 3 and the high-temperature-resistant rubber 14 for sealing, wherein the bottom of the oil storage ring groove 6 is contacted with the pressing plate 3, and the upper end surface of the oil storage ring groove is flush with the end surface of the pressing plate 3; as shown in fig. 1 and 2, the adjusted multi-point flexible mold is mounted on a locking device, all locking bolts 19 fixed on a pressing plate 3 are taken down, two groups of carbon fiber yarns 17-1 and 17-2 respectively loosen a line clamp 18 on one side, a locking linkage hydraulic control loop is used for filling liquid with the same pressure to four locking hydraulic cylinders 16, so that the locking hydraulic cylinders 16 have certain locking force, the four pressing plates 3 move towards the middle and compress the high-temperature-resistant rubber 14 for sealing, and the basic unit 4 group is locked under the indirect action of the pressing plate 3;

the fifth step: putting the plate 2 into the oil storage ring groove 6, pressing the edge for sealing, pouring a certain amount of high-temperature-resistant sealing oil into the oil storage ring groove, and enabling the oil storage ring groove to be in contact with the plate 2 during pressing the edge at high temperature to realize sealing; as shown in fig. 2, the plate 2 is put on a multi-point flexible mould with the adjusted profile, so that the plate is attached to the upper end of the pressure plate 3, the upper end of the oil storage ring groove 6 and the upper end of the high-temperature resistant rubber 14 for sealing; putting the blank holder 1, attaching the blank holder flange 5 to the upper end of the plate 2, and simultaneously enabling the groove of the oil storage ring groove 6 to be superposed with the arc symmetrical surface of the blank holder flange 5; the pressure in the three edge pressing hydraulic cylinders 12 is controlled to be consistent all the time by using an edge pressing linkage hydraulic loop, the hydraulic cylinders 13 are in contact with the upper end surface of the edge pressing ring 1 by filling liquid and give a certain pressure, and in an initial state, the end surfaces of the three hydraulic cylinder pistons 13 close to one side of the plate 2 are flush so as to ensure that the pressure applied to the plate 2 at three positions is consistent;

and a sixth step: forming the plate, namely heating the plate 2 to raise the temperature of the plate to a formable temperature range; referring to fig. 2 and 13, air is extracted from a bell mouth of the high-temperature-resistant rubber 14 for sealing, a certain negative pressure is maintained in a cavity 7 formed by adjusting a multi-point flexible mold close to one side of the plate 2, the high-temperature plate 2 is attached to the envelope surface of the basic unit body 4 group under the action of outside atmospheric pressure, the forming of the plate 2 is completed, and meanwhile, closed-loop control and real-time adjustment of negative pressure and blank-pressing pressure in the cavity can be performed on the forming process by monitoring the pressure born by each basic unit body 4 and the negative pressure value in the cavity 7; and cooling and maintaining the pressure after the forming is finished, releasing the pressure in the blank holder hydraulic cylinder 12, taking out the blank holder 1, taking out the formed piece and finishing the process.

Claims

1. A flexible forming apparatus for thermoplastic material, characterized by: the multi-point flexible mold is embedded in the locking device, and the flexible blank pressing system is arranged on the locking device;

the multipoint flexible mold comprises four pressing plates (3), wherein the four pressing plates (3) are respectively a left pressing plate (3-1), a right pressing plate (3-2), an upper pressing plate (3-3) and a lower pressing plate (3-4), the four pressing plates form a square frame, high-temperature-resistant rubber (14) for sealing is arranged in the square frame, a plurality of groups of square grids formed by inserting carbon fiber yarns (17) are arranged in the high-temperature-resistant rubber (14) for sealing, basic unit bodies (4) with square sections are installed in the square grids, and the ends of the carbon fiber yarns (17) are fixed on the pressing plates (3) through line cards (18);

the locking device comprises an outer frame (9), a locking hydraulic cylinder (16) is fixed on the inner side surface of the outer frame (9), an output shaft of the locking hydraulic cylinder (16) is in contact with the outer side of the pressure plate (3), the locking hydraulic cylinder (16) is controlled by a locking hydraulic control loop, and an L-shaped plate (10) is fixed on the outer side surface of the outer frame (9);

flexible blank pressing system include stand (11), stand (11) lower extreme is fixed on frame (9), stand (11) upper end is fixed with blank pressing pneumatic cylinder (12), pneumatic cylinder piston (13) and blank holder (1) up end laminating of blank pressing pneumatic cylinder (12), the terminal surface links firmly blank pressing flange (5) under blank holder (1), blank pressing flange (5) cambered surface and panel (2) laminating, place on clamp plate (3) panel (2), embedded oil storage annular (6) on clamp plate (3), oil storage annular (6) medial surface and sealed high temperature resistant rubber (14) laminating of using, blank pressing pneumatic cylinder (12) are by blank pressing hydraulic control return circuit control.

2. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the main bodies of the left pressing plate (3-1), the right pressing plate (3-2) and the upper pressing plate (3-3) are cuboids, the section of the lower pressing plate (3-4) is in a convex shape, the four pressing plates are the same in length direction size, and two end faces are flush; in an initial state, the four pressing plates are fixedly connected together through locking bolts (19) to form a square frame, a series of small through holes are regularly arranged on the outer side surface of the square frame, carbon fiber wires (17) penetrate through the through holes, and the inner side surface of the square frame is attached to high-temperature-resistant rubber (14) for sealing to form a sealed inner cavity.

3. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the carbon fiber filaments (17) are high-strength carbon fiber filaments with the diameter smaller than 1mm, and are divided into two groups, namely upper and lower carbon fiber filaments (17-1) for the pressing plate and left and right carbon fiber filaments (17-2) for the pressing plate according to the distribution direction, the upper and lower pressing plates penetrate through the upper pressing plate and penetrate out of the lower pressing plate, the left and right pressing plates penetrate through the left pressing plate and penetrate out of the right pressing plate, the carbon fiber filaments (17-2) for the pressing plate are continuously alternated for multiple times between the left and right pressing plates or between the upper and lower pressing plates, multiple groups of square grids are formed in the sealing high-temperature-resistant rubber (14), the two groups of carbon fiber filaments which are alternated up and down and left and right are in tangential contact at the square grids, the side length of each square grid is equal to that of the basic unit.

4. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the basic unit body (4) is a cuboid with a square cross section, a circular through hole is formed in the center of the cross section, the side length of the cuboid is smaller than 5mm, a pressure sensor is installed on the end face, close to one side of the plate (2), of the basic unit body (4) and used for monitoring the pressure in the cavity (7) and the axial pressure born by each basic unit body (4), and the basic unit body (4) is installed in a square grid formed by carbon fiber yarns (17) and can move along the axis of the through hole in the square grid.

5. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the high-temperature-resistant rubber for sealing (14) is of a hollow structure in a shape of 'hui', the end close to the plate (2) is of a horn mouth shape, and the side face of the high-temperature-resistant rubber is provided with a small through hole for the carbon fiber yarn (17) to pass through.

6. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the outer frame (9) is in a hollow hat shape, one end close to the plate (2) is a hat brim, and the other end is in a 'return' shape; the number of the locking hydraulic cylinders (16) is four, the output shaft of the first locking hydraulic cylinder (16-1) is in contact with the left pressing plate (3-1), the output shaft of the second locking hydraulic cylinder (16-2) is in contact with the right pressing plate (3-2), the output shaft of the third locking hydraulic cylinder (16-3) is in contact with the upper pressing plate (3-3), the output shaft of the fourth locking hydraulic cylinder (16-4) is in contact with the lower pressing plate (3-4), and the output shafts of the four locking hydraulic cylinders are located in the center of the corresponding pressing plate (3).

7. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the pressing plate (3) is provided with a rectangular groove at one side close to the plate (2), the rectangular grooves of the four pressing plates are connected to form an annular groove, and an oil storage annular groove (6) is arranged in the annular groove.

8. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: the upright columns (11) are inverted L-shaped and are respectively arranged at the left side, the right side and the center of the rear side of the end surface of the visor of the outer frame (9), and the left upright column and the right upright column are symmetrical relative to the central upright column of the rear side.

9. A thermoplastic material flexible forming apparatus, as defined in claim 1, wherein: oil storage annular (6) be square ring shape, the cross-section is "concave" shape, middle concave recess is the arc, its radian slightly is less than the radian of blank pressing flange (5), oil storage annular (6) are installed in clamp plate (3) are close to the terminal surface inslot of panel (2) one side, the groove of oil storage annular (6) and the coincidence of the arc symmetry plane of blank pressing flange (5).

10. A method of forming a flexible thermoplastic forming apparatus in accordance with claim 1, comprising the steps of:

the first step is as follows: aiming at the three-dimensional curved surface to be formed, acquiring the three-dimensional information of the part to be formed by a reverse engineering means, and calculating the height of each basic unit body (4) to be adjusted by using calculation software;

the second step is that: firstly, placing high-temperature-resistant rubber (14) for sealing on the upper top surface of a lower pressing plate (3-4), installing a left pressing plate (3-1) and a right pressing plate (3-2) on the lower pressing plate (3-4), fixing the upper pressing plate (3-3) on the left pressing plate (3-1) and the right pressing plate (3-2), wherein the four pressing plates form a square frame, the high-temperature-resistant rubber (14) for sealing is in an original non-compression state, an inner frame formed by the four pressing plates is attached to the outer frame surface of the high-temperature-resistant rubber (14) for sealing, and the relative positions of the four pressing plates are fixed through connection of locking bolts (19); carbon fiber yarns (17) are inserted between the left pressing plate (3-1) and the right pressing plate (3-2), the upper pressing plate (3-3) and the lower pressing plate (3-4), and two ends of each carbon fiber yarn are fixed on the pressing plates (3) through wire clamps (18); the carbon fiber yarns form a plurality of groups of square grids, the basic unit bodies (4) are inserted into the square grids, and all the basic unit bodies (4) are flush on one side far away from the plate (2);

the third step: adjusting the shape of the mould, namely automatically adjusting the hollow basic unit body (4) to a corresponding position from one side close to the plate (2) by using a shape adjusting device, so that a curved surface to be formed is enveloped at one side of a pressure sensor of the hollow basic unit body (4) group, thereby forming a cavity (7) with a specific shape; the four locking hydraulic cylinders (16) are filled with liquid with the same pressure by using a locking linkage hydraulic control loop, so that the four pressing plates (3) move towards the middle and compress the high-temperature-resistant rubber (14) for sealing, and the adjusted basic unit body (4) keeps the shape; fixing the multi-point flexible mould on a forming test bed through an L-shaped plate (10);

the fourth step: locking the mould, namely installing an oil storage ring groove (6) on a multi-point flexible mould, installing the adjusted multi-point flexible mould on a locking device, loosening a line clamp (18) of carbon fiber yarns on one side, filling liquid with the same pressure into four locking hydraulic cylinders (16) by using a locking linkage hydraulic control loop, and moving four pressing plates (3) towards the middle and pressing high-temperature-resistant rubber (14) for sealing so as to lock a basic unit body (4) group under the indirect action of the pressing plates (3);

the fifth step: putting the plate (2) into the oil storage ring groove (6), pressing the plate to seal, pouring high-temperature-resistant sealing oil into the oil storage ring groove, and enabling the oil storage ring groove to be in contact with the plate (2) to realize sealing when pressing the plate at a high temperature; placing the plate (2) on a multipoint flexible mould with an adjusted molded surface, and attaching the plate to the upper end of the pressure plate (3), the upper end of the oil storage ring groove (6) and the upper end of the high-temperature resistant rubber (14) for sealing; putting the blank holder (1) into the oil storage tank, enabling the blank holder flange (5) to be attached to the upper end of the plate (2), and enabling the groove of the oil storage ring groove (6) to be overlapped with the arc symmetrical surface of the blank holder flange (5); the pressure in the three edge pressing hydraulic cylinders (12) is controlled to be consistent all the time by using an edge pressing linkage hydraulic loop, and the hydraulic cylinder piston (13) is contacted with the upper end surface of the pressing plate (3) by filling liquid;

and a sixth step: the plate is formed, and the plate (2) is heated to raise the temperature to a formable temperature range; air is extracted from a bell mouth of high-temperature-resistant rubber (14) for sealing, a certain negative pressure is kept in a cavity (7) formed by adjusting a multi-point flexible mold close to one side of the plate (2), the high-temperature plate (2) is attached to the envelope surface of the basic unit body (4) group under the action of outside atmospheric pressure, the forming of the plate (2) is completed, and meanwhile, closed-loop control is carried out on the forming process and the negative pressure and the blank pressing pressure in the cavity are adjusted in real time by monitoring the pressure born by each basic unit body (4) and the negative pressure value in the cavity (7); and cooling and maintaining the pressure after the forming is finished, releasing the pressure in the blank holder hydraulic cylinder (12), taking out the blank holder (1), taking out the formed piece, and finishing the process.