CN109622778B

CN109622778B - Molded surface compensation method for die debugging

Info

Publication number: CN109622778B
Application number: CN201811338055.8A
Authority: CN
Inventors: 李成; 刘明; 何奇志
Original assignee: Dongfeng Die Stamping Technology Co ltd
Current assignee: Dongfeng Die Stamping Technology Co ltd
Priority date: 2018-11-12
Filing date: 2018-11-12
Publication date: 2021-03-19
Anticipated expiration: 2038-11-12
Also published as: CN109622778A

Abstract

The invention relates to a molded surface compensation method for debugging a mold, which comprises the step of baking a corresponding area of a molded surface of a convex-concave defect area of a workpiece surface by using flame, wherein the range of the convex-concave defect area of the workpiece surface is not more than 50mm multiplied by 100mm, and the height difference in the convex-concave defect area of the workpiece surface is not more than 0.1 mm. The molded surface compensation method for debugging the die can provide a certain amount of grinding under the condition that the defects are not eliminated but no grinding amount exists, so that the defects of the workpiece can be continuously and quickly dealt with.

Description

Molded surface compensation method for die debugging

Technical Field

The invention belongs to the technical field of stamping dies for automobile outer covering parts, and particularly relates to a molded surface compensation method for die debugging.

Background

In recent years, the quality of a stamped part, particularly an outer cover, is required to be higher and shorter in each automobile main machine factory, and the manufacturing cycle is also required to be shorter and shorter. At present, the quality of the first-time workpiece output can be greatly improved by methods such as CAE simulation optimization in the early stage, reservation and addition of various empirical data and the like, but part of the area is limited by product characteristics or stamping process characteristics, and the appearance defect of the molded surface still needs to be eliminated and improved by a manual debugging method. For example, in order to solve the problem of convex-concave profile of a stamping part, the profile of the stamping part is reserved in a region where defects are easy to generate, the processing comprises convex die bulging and concave die pressing, and then manual grinding and adjustment are performed according to actual defects of parts. However, the manual fabrication has certain technical difficulty and is limited by the fineness of the reservation countermeasure, so that the problem that the appearance defect cannot be eliminated after the reserved quantity is ground and repaired may occur, if the common welding repair mode is adopted to increase the grinding quantity of the molded surface, a large amount of production resources need to be consumed, and meanwhile, the welding mode also needs to bear the risk of poor welding quality.

In view of the foregoing, a need exists for a fast and economical profile compensation method for mold tuning.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a profile compensation method for debugging a mould, which can provide a certain amount of repair under the condition that the defects of a manufactured part are not eliminated but the mould profile has no repair amount, so that the defects of the manufactured part can be continuously and quickly dealt with.

The molded surface compensation method for debugging the mold comprises the step of baking a corresponding area of the molded surface of the mold of a convex-concave defect area of a workpiece surface by using flame, wherein the range of the convex-concave defect area of the workpiece surface is not more than 50mm multiplied by 100mm, and the height difference in the convex-concave defect area of the workpiece surface is not more than 0.1 mm.

The method for enabling the mold surface to deform and bulge by flame baking greatly saves the manufacturing working hours of the mold surface repair, avoids the risks of blowholes, cracks and the like caused by the mold surface welding repair, does not need to use machining equipment, accelerates the debugging progress of the mold, and greatly reduces the debugging repair cost of the appearance defects of the stamping parts.

In the invention, the range of the convex-concave defect area of the surface of the workpiece is not more than 50mm multiplied by 100mm, namely the long side cannot be more than 100mm, and the short side cannot be more than 50mm, and if the range is more than the range, the corresponding area of the molded surface of the die cannot reach the maximum value, and the convex-concave situation of the raised surface can occur after baking.

The height difference of the convex-concave defect area on the surface of the workpiece is not more than 0.1mm, and if the height difference exceeds the grade, the flame baking bulge amount is not enough to solve the defects, and other ways need to be considered for lightening or reducing the defect grade.

Further, the baking temperature of the corresponding area of the molded surface of the die is 900-1000 ℃.

Further, the flame moves in a spiral-type outside-in direction, and the moving speed of the flame is 10 mm/s.

Further, the amount of protrusion after each flame baking is 0.03mm to 0.05 mm.

Further, the baking times of the corresponding area of the mold surface do not exceed 4 times.

The amount of the bulge is different according to different die manufacturing materials, and certain limiting conditions are provided for the baking operation on the premise of ensuring that the quality of molded surface castings in a baking area is not damaged. For example: the mold made of gray iron (HT250 and HT300) has the single bulging amount of 0.03mm-0.04mm after flame baking and the maximum bulging amount of about 0.12mm after multiple times of baking; the mold made of alloy ductile iron (QT600, QT700 and MoCr) has a single bulging amount of 0.04mm-0.05mm after flame baking and a maximum bulging amount of about 0.18mm after multiple times of baking. The number of times of baking is also different depending on the material used for the mold. For example: the mold made of HT300 can be baked for no more than 3 times; the mould made by QT600 can be baked for no more than 4 times. If the casting temperature exceeds the set temperature, defects such as casting carbonization, shrinkage cavity and the like can occur on the mould surface.

Further, before baking by using flame, the concave-convex defect area of the surface of the part is copied to the position of the corresponding molded surface of the mold by using translucent paper.

The use of the translucent paper for copying can ensure the accurate position of the baking operation.

Further, after baking is finished, when the ambient temperature is higher than 10 ℃, naturally cooling; and when the ambient temperature is less than or equal to 10 ℃, covering asbestos on the corresponding area of the molded surface of the die and then naturally cooling.

After one baking operation is finished, the temperature of the area to be baked is recovered to the room temperature, and then the next baking operation is carried out. After the baking operation of the molded surface of the die is finished, when the environmental temperature is higher than 10 ℃, the baked part of the molded surface is naturally cooled; when the environment temperature is less than or equal to 10 ℃ in the baking area, the difference between the temperature and the room temperature is large, and the baking part of the molded surface is easy to crack, so that the corresponding area of the molded surface of the die can be covered with asbestos cloth to slowly cool to the room temperature.

And removing oxide skin on the surface of the corresponding area of the molded surface of the die after finishing the preset baking operation turns, and then carrying out blue light scanning to confirm the uplift amount of the molded surface of the die. If not, the baking operation can be performed again according to the difference between the current actual protrusion amount and the expected protrusion amount. If the baking area has punctiform holes, the baking operation can not be carried out again, so as to avoid causing the poor quality of the molded surface of the die and further forming serious quality defects.

The invention has the beneficial effects that:

the profile compensation method for debugging the die adopts a flame baking mode to bake and heat the profile of the die to enable the profile to bulge, and provides a certain amount of grinding for the bench worker to grind and repair so as to continuously and quickly cope with the profile defect. The technology can also be used for the conditions of poor lapping of a local pressure plate in the post-process, virtual lapping of a local shaping profile and the like, avoids the defects of cracks, sand holes and the like generated by welding the profile of the die, reduces the use of finish machining equipment for numerical control processing, greatly shortens the coping period of the defects, improves the production efficiency and reduces the production cost.

Drawings

FIG. 1 illustrates the mold baking principle when the defect is concave;

FIG. 2 illustrates the mold baking principle when the defect is convex;

FIG. 3 is a graph of the effect of using a flame to bake the mold surface 2 times (right) and 3 times (left);

FIG. 4 is a schematic illustration of the profile of FIG. 3 using blue light to verify the amount of tenting;

FIG. 5 is a schematic view of the door handle of the present invention;

FIG. 6 is a flow chart illustrating the formation of a door handle having a male-female defect according to the present invention;

FIG. 7 is a schematic view of a door handle surface asperity defect according to the invention;

FIG. 8 is a schematic view of a strong pressure area provided at the door handle of FIG. 7;

FIG. 9 is a schematic view of the door handle of FIG. 7 showing a non-defect-free and non-lap area after the door handle of FIG. 8 has taken the counter measure of the overpressure reserve;

FIG. 10 is a schematic view of a defect area in the door handle of FIG. 7 after the counter measure of the over-pressure preservation shown in FIG. 8 is applied;

FIG. 11 is a schematic view illustrating measurement of the amount of convex-concave deformation in the defective area of the door handle shown in FIG. 10;

FIG. 12 shows the surface roughness of each measurement point on the corresponding measurement line of FIG. 11;

FIG. 13 is a schematic view showing the moving direction of the corresponding zone of the female mold surface during the baking with flame.

FIG. 14 shows the surface roughness of each measurement point on the measurement line after flame baking;

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings, but the embodiments are not intended to limit the present invention and are merely examples.

Under the normal condition, after the strong pressure grinding state is ensured, the convex-concave deformation of the molded surface of the workpiece can be controlled below 0.10mm, at the moment, the convex die or the concave die needs to be slightly ground according to the defect condition of the workpiece, and the operation needs higher operation skill level. The specific principle is that the convex-concave direction of the defects of the workpiece is confirmed by using oilstones. And judging whether the generation reason of the defects of the workpiece is the unsmooth molded surface caused by the bulges or the depressions. If the defect is shown in figure 1, when the defect in the area a is concave, the position of the convex die corresponding to the concave area a is ground and repaired along the peripheral molded surface b, so that the molded surface at the position a of the convex die is higher than the molded surface at the position b, the molded surface at the position a of the convex die contacts the plate material firstly, and the defect grade is reduced. If the defect of the area c is convex as shown in figure 2, the position of the concave die corresponding to the defect c is ground and repaired along the peripheral molded surface d, so that the molded surface at the position of the defect c of the concave die is higher than the molded surface at the position d, and the concave die controls the plate material at the position c to reduce the defect grade. If the amount of the grinding position and the grinding amount is not properly controlled during the grinding operation, the defect of the molded surface can not be resolved without the grinding adjustment amount. When the situation occurs, the manual grinding operation can not cope with the defects, and the next round of debugging grinding can be performed only after the reserved quantity is recovered through other ways.

FIG. 3 shows the actual effect of using flame to bake 50mm by 50mm area mold surface 2 times and 3 times; fig. 4 is a graph comparing the amount of protrusion verified by its corresponding blue scan.

Example 1

The application of the profile bulging technique by flame baking in mold debugging is specifically described by taking an automobile door outer panel door handle as an example.

As shown in fig. 5 and 6, through the analysis of the molding process, the shape of the door handle area is complex, the length difference of the lines exists in the material extending direction, the stress states of the molded surfaces at all positions are inconsistent, the surface unevenness generated by the uneven stress generated in the molding process is amplified after the stress is released, and the defect of unevenness is certainly left. The door handle often has a concave-convex profile as shown in fig. 7.

In order to improve the profile defect a shown in fig. 7, it was first tried to provide a strong pressure region B of 0.20mm and a strong pressure transition region C shown in fig. 8 on the die side. Because the specific position of convex-concave generation is difficult to accurately judge, the whole area is forced to reduce the defect grade, so that the forced area of the area is set to be a uniform numerical value under the normal condition, and the whole area is uniformly researched. After the workpiece is taken out, the mold is debugged on site, and for various reasons, the problem of the convex and concave profile is not solved for many times by grinding and repairing, and the condition that the grinding and repairing amount is not continuously adjusted at the position D shown in figure 9 is caused. The surface bulge is confirmed by the oilstone, and in order to eliminate the bulge defect of the part, the surface of the female die side needs to be restored, and then subsequent grinding and repairing are carried out.

The profile compensation method comprises the following steps:

1. it was confirmed whether the recovery profile could be fired. As shown in fig. 10, the position and range of the defective region D of the workpiece are confirmed by oilstone or visual inspection, then the measurement as shown in fig. 11 is performed by using a three-point gauge, detection lines E1 and E2 are set (the detection line length usually exceeds the range of the defective region E of the workpiece), detection points are set on the detection lines E1 and E2 at intervals of 5mm to obtain the measurement result as shown in fig. 12, the difference between the peaks and the valleys on each detection line is calculated to obtain the amount of concave-convex deformation of the profile on the detection line, and the maximum value among the amounts of concave-convex deformation of the profile is called the height difference of the defective region E of the workpiece.

The range of the defective area E of the grip element is 30mm x 75mm and the height difference is 0.044 mm. In the judgment of the appearance defect grade of the existing stamping part, the height difference of more than 0.040mm in the range of 50mm belongs to the V2 defect needing sheet metal repair, and VES illumination evaluation cannot pass. Height difference less than 0.030mm belongs to acceptable V3 grade defects without sheet metal, and can be evaluated through VES illumination. And illumination evaluation is needed between the two to judge whether further repair is needed.

2. The raised area was confirmed. A piece of transparency paper is laid over the handle piece to delineate the location, features and features of the adjacent areas of the defect area E. Covering the drawn transparent paper on the molded surface of the female die, copying an accurate position on the molded surface of the female die to obtain a corresponding area of the molded surface of the die, and determining the central position of the baking operation according to the area with the largest surface difference measured by the three point gauges.

3. The amount of tenting is expected. The expected amount of bulging required for the mold surface was confirmed for the measured level difference, which was at least 1.5 times the convex-concave level difference of the product surface. Corresponding to the defect of the handlebar, the profile bulging amount of the female die can be set to be 0.08mm, the female die is made of FC300, repeated operation caused by the fact that the required bulging amount cannot be achieved by 2 times of flame baking is avoided, and the required bulging amount can be achieved by directly performing 3 times of flame baking.

4. Preheating in the early stage. The invention uses acetylene spray gun for surface quenching, the acetylene pressure is set to be 1.0Mpa, and the oxygen pressure is set to be 0.5 Mpa. In order to prevent the molding surface of the die from cracking or local material carbonization caused by too fast temperature rise, the range of +80mm of the periphery of the corresponding area of the molding surface of the die is set as an integral preheating area, and the molding surface of the preheating area is firstly heated to 300 ℃ within 30-40 seconds.

5. And finishing one baking operation. The length of the flame is controlled to be about 60mm, the distance between the flame nozzle and the mold surface is kept to be about 30mm, the flame is moved at the speed of 10mm/s in the direction (spiral type from outside to inside) shown by an arrow in figure 13 by utilizing the outer flame of the flame, and the corresponding area of the mold surface of the mold is heated to 900-1000 ℃ (the temperature can be judged by field operators according to the color change of the heated mold surface). Then, the room temperature was naturally cooled (this operation time was summer).

6. The baking operation is repeated. And (5) repeating the

steps

4 and 5 twice when the temperature of the corresponding area of the molded surface of the mold is reduced to the room temperature.

7. The amount of swelling was confirmed. After the molded surface is cooled to room temperature (corresponding to the previous content, oxide scale is removed firstly), the raised area is scanned by using a blue light scanning device, whether the actual raised amount and the raised range are the same as the expected requirement or not is confirmed, and data basis is provided for fitter correction.

And (3) carrying out profile polishing operation by using No. 240 sand paper, removing surface scale to obtain a reference die, then taking out the appearance detection part again, rubbing and grinding the raised area according to a new defect state until a required improvement effect is achieved, improving the surface convex-concave height difference to 0.025mm as shown in figure 14, and evaluating through VES illumination.

Before the door handle convex-concave defect is treated by the method, the door handle convex-concave defect is treated by using an over-welding method and an integral surface-reducing method, but the latter two methods have obvious high cost and low efficiency, and are specifically as follows:

(a) the profile is restored to defective position welding reprocess, and the expense that a round of was revised needs is about: the method comprises the following steps of profile welding, data manufacturing, numerical control processing, benchmark manufacturing, die assembly and press debugging, and is as follows: 100 x 1+100 x 2+800 x 2+60 x 2+800 x 3-3860-membered; the time consumption is 12 h.

(b) The mould is wholly reduced the type face and reprocessed, and the required expense of a round of correction is about: numerical control processing, benchmark preparation, mould assembly, press debugging are about: 800 × 26+60 × 6+60 × 2+800 × 3 ═ 23680 elements; consuming time; it takes 37 hours of man-hours.

(c) The flame baking restores the molded surface to repair, and the cost required by one round of repair is about: flame baking, reference manufacturing and press debugging are as follows: 100 x 1+60 x 1+800 x 3 ═ 2560 members; it takes 5 hours of time.

The above (a), (b) and (c) are respectively a round of repair cost and working time of a welding method, an integral profile lowering method and a flame baking method, the difference is obvious, generally, the debugging of the automobile mould needs 3-7 rounds, and after the overall calculation, the flame baking method is more suitable for being popularized in the mould debugging production.

Details not described in this specification are within the skill of the art that are well known to those skilled in the art.

Claims

1. A molded surface compensation method for die debugging is characterized in that: and (2) baking a die profile corresponding area of the convex-concave defect area of the workpiece surface by using flame, wherein the range of the convex-concave defect area of the workpiece surface is not more than 50mm multiplied by 100mm, the height difference in the convex-concave defect area of the workpiece surface is less than 0.1mm, the baking temperature of the die profile corresponding area is 900-1000 ℃, and the bulging amount after each flame baking is 0.03-0.05 mm.

2. The profile compensation method for mold commissioning as recited in claim 1, wherein: the flame moves in a spiral-type outside-in direction, and the moving speed of the flame is 10 mm/s.

3. The profile compensation method for mold commissioning as recited in claim 2, wherein: the baking times of the corresponding area of the molded surface of the die do not exceed 4 times.

4. The profile compensation method for mold commissioning of any one of claims 1-3, wherein: before flame baking, the surface relief defect areas of the part were replicated onto the mold surface using translucent paper.

5. The profile compensation method for mold commissioning as recited in claim 4, wherein: after baking, naturally cooling when the ambient temperature is higher than 10 ℃; and when the ambient temperature is less than or equal to 10 ℃, covering asbestos on the corresponding area of the molded surface of the die and then naturally cooling.