JP6541108B2 - Method of manufacturing cylindrical sintered parts - Google Patents

Description

  The present invention relates to a method of manufacturing a cylindrical sintered part having unevenness on the end face of the cylindrical body, and more specifically, the convex portion of the end face of the cylindrical body takes out the molded body from the mold in the powder forming step ( The present invention relates to a method of making it possible to manufacture parts by powder metallurgy that do not have strength enough to withstand the force applied during kicking.

  An example of the cylindrical part considered to be difficult to manufacture by powder metallurgy is shown in FIG. 7 and FIG. The tubular part 10 has a ratchet claw 12 at one end of a tubular body 11 with a sharp tip and a thin wall thickness (for example, 5 mm or less). At the other end, an inner flange 14 with an axial hole 13 is provided.

  If this cylindrical part 10 is to be manufactured by powder metallurgy, a powder molding die as shown in Patent Document 1 below, that is, a die, a core, a plurality of lower punches, and an upper punch are combined. A raw material powder is shape | molded using a powder molding die, and the method of sintering the molded object of the obtained powder after that will be taken.

JP, 2012-245563, A

  For example, molding of the cylindrical part 10 with the powder molding die shown in FIGS. 7 and 8 is carried out by using a die of the powder molding die for the outer peripheral surface of the cylindrical body 11 and a core rod for the shaft hole 13 and ratchet claws. The inner surface of the inner flange 14 and the inner peripheral surface of the cylindrical body 11 are formed by the lower 2 punches, and the outer surface of the inner flange 14 is formed by the upper punch.

  According to this method, compression molding of the raw material powder can be performed without any problem. However, when the powder compact obtained by compression molding is kicked out of the mold, the ratchet claw 12 which is weak in strength is broken.

  The method to lower the die, lower 2 punches and core under the condition that lower 1 punch is supported by lower 1 punch which formed the surface with ratchet claw 12 and the lower 1 punch is fixed. At this time, the draw-down force of the die, the lower two punches and the core is applied to the molded body in contact with those dies, so that the ratchet claw 12 is cracked or chipped.

  The protrusion provided at one end of the cylindrical body has a small thickness and a narrow width, so that a chipping at the time of kicking out (during die removal) is avoided even if the tip is not sharp like a ratchet claw I can not.

  Because of the problem, it has been considered impossible to manufacture by the powder metallurgy method for cylindrical parts 10 as shown in FIG. 7 and FIG. 8 in which the weak convex portion is on the end face.

  7 and 8 can be manufactured by using a method of machining the end face with irregularities after forging or casting, but these methods have poor mass productivity and a low manufacturing cost. It costs money.

  Then, an object of this invention is to enable manufacture by the powder metallurgy method about the part which has an intensity | strength inadequate at the stage of a powder compact in the end surface of a cylindrical body part.

A method of manufacturing a cylindrical sintered part according to an aspect of the present invention is to manufacture a sintered part having irregularities on one end face of a cylindrical body, and the cylindrical body in the step of forming the raw material powder. Forming an increased thickness portion integrally with the outer circumference or the inner circumference of the cylindrical body to increase the thickness of the cylindrical body over the entire circumference,
The compact obtained after powder compression is supported by a first lower punch formed by molding one end face of the increased thickness portion, and under this condition, other mold elements except the first lower punch and the upper punch Pull the mold out of the mold, and
Thereafter, the molded body is sintered, and the thickened portion is removed by machining to obtain a target sintered part.

  According to the method of the present invention, it is possible to manufacture a sintered part having a convex portion which is insufficient in strength at the stage of a molded body and is easily broken at the end face of the cylindrical body without cracking or chipping of the convex portion. be able to.

  In addition, the removal of the said thickness-increasing part can be performed by the simple operation which only grinds an outer periphery and inner periphery using machine tools, such as a lathe.

  Therefore, the advantages of powder metallurgy can be fully utilized, and the productivity is superior to a method in which cylindrical blanks are forged or cast and then machined to form irregularities on the end face of the blank, The manufacturing cost can also be reduced.

It is a partially broken side view which shows an example of the molded object obtained by die-molding by the manufacturing method of this invention. It is sectional drawing which shows the powder supply process in metal mold molding of the molded object of FIG. It is sectional drawing which shows the powder compression completion state in metal mold molding of the molded object of FIG. It is sectional drawing which shows the pre-step process of the kicking-out after powder compression completion. It is sectional drawing which shows the next step process of the kicking-out after powder compression completion. It is sectional drawing which shows the final stage process of the kicking-out after powder compression completion. It is a perspective view showing an example of a cylindrical sintered part manufactured by a method concerning one mode of the present invention. It is a partially broken side view of the cylindrical sintered component of FIG.

Description of the embodiment of the present invention
In the method of manufacturing a cylindrical sintered component according to one aspect of the present invention, a sintered component having an unevenness at one end of the cylindrical body is manufactured. In the step of forming the raw material powder in the method, an increase in thickness is integrally formed on the outer periphery of the cylindrical body so as to increase the thickness of the cylindrical body over the entire periphery.

  The molded product additionally provided with the thickness-increasing portion has a die on the outer peripheral surface of the thickness-increasing portion, a first lower punch on one end face of the thickness-increasing portion, and a second The inner peripheral surface of the cylindrical body portion is formed by the third lower punch or core rod, and the other end surface of the cylindrical body portion including the other end surface of the thickened portion is formed by the upper punch.

  The first lower punch supports one end face of the thickened portion, and under this condition, the second lower punch and the third lower punch (there is also a mold without the third lower punch). The core rod is pulled down, and the finished molded body is taken out of the mold (take-out kicking).

  The shaped body thus obtained is then sintered. And, if necessary, sizing is performed to increase the roundness and the like, and then the thickened portion is removed by machining.

  When the cylindrical sintered component to be manufactured is provided with an inner flange having an axial hole at the other end, the third lower punch is provided, and the third lower punch and the inner peripheral surface of the cylindrical body portion The inner end faces of the inner flange are respectively molded. The inner peripheral surface of the shaft hole is formed of a core rod, and the upper punch forms the other end surface of the cylindrical body including the other end surface of the thick portion and the outer end surface of the inner flange.

  When manufacturing the cylindrical sintered component which does not have an inner flange in the other end, shaping | molding of the internal peripheral surface of a cylindrical body part is performed by a core rod.

  The thickened portion may be provided on the inner periphery of the cylindrical body. In this case, the outer circumferential surface of the cylindrical body is a die, and the inner circumferential surface of the thickened portion is a third lower punch or core rod. Each is molded.

  Also, in this case, a lower punch (lowermost punch in the radial direction), usually referred to as a lower 1 punch, is the second lower punch, so the lower 1 punch (a second lower punch) Forming one end surface of the cylindrical body portion, and further, the second lower punch (counting from the outer side in the radial direction referred to as the lower 2 punch) is performed on one end face of the thick portion. Lower punch)

  Further, the inner peripheral surface of the thickness-increasing portion is formed with a third lower punch (third lower punch according to the present invention) or a core rod counting from the radial outer side called lower 3 punches.

  With respect to the cylindrical sintered part having the inner flange, the third lower punch also forms the inner end face of the inner flange.

  According to the manufacturing method of the cylindrical sintered part, since the support of the molded body at the time of taking out the molded body from the mold is performed by the first lower punch formed by molding one end face of the thick portion, the cylindrical body portion No load is applied to the convex part at one end of.

  Therefore, it becomes possible to manufacture stably the part which has a convex part whose intensity | strength is not enough at the stage of a molded object by the powder metallurgy method at one end of a cylindrical trunk | drum.

  In addition, since the thickness of the cylindrical body portion of the formed body is increased by the installation of the thickness-increasing portion, the cylindrical sintered component having a thin cylindrical body portion whose thickness does not reach, for example, 5 mm at the product stage The filling property of the raw material powder into the mold cavity is improved.

  Furthermore, since the thickened portion is still left at the sintering stage, distortion (deterioration of cylindricity) due to sintering of the molded body is also suppressed. Such excellent incidental effects can also be expected.

Preferably, one end face of the thickness-increasing part is protruded forward in the projecting direction of the projection than the point of the projection provided on one end of the cylindrical body. In this way, when handling the molded body taken out of the mold, it is possible to prevent the situation where the tip of the convex portion falls off against the external object.
Details of the Embodiment of the Present Invention
Specific examples of the method for producing a cylindrical sintered component according to one aspect of the present invention will be described below with reference to the drawings. The present invention is not limited to these examples, but is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

  The illustrated manufacturing method has the cylindrical part shown in FIGS. 7 and 8, that is, the end of the cylindrical body portion 11 has the ratchet claw 12 having a sharp tip and a thin wall at the other end, and the shaft at the other end. A tubular part 10 having an inner flange 14 with a hole 13 is manufactured by powder metallurgy.

  The cylindrical part 10 is manufactured by producing a molded body 15 having a shape as shown in FIG. 1 in the raw material powder molding step.

  In the molded body 15 of FIG. 1, a thickened portion 16 for increasing the thickness of the cylindrical body portion is integrally provided on the outer periphery of the cylindrical body portion 11.

  A powder molding die used for molding the molded body 15 is shown in FIG. This powder molding die 1 includes a die 2, a first lower punch (the lower one punch in the figure) 3, a second lower punch (the lower two punch in the figure) 4 and a third lower punch ( In the figure, lower 3 punches 5, core rod 6 and upper punch 7 are combined.

  The die 2 shapes the outer peripheral surface of the thickness increasing portion 16 provided on the outer periphery of the cylindrical body portion 11 of the molded body. The first lower punch 3 forms one end face of the thickness increasing portion 16, and the second lower punch 4 forms a ratchet claw 12 provided at one end face of the cylindrical body 11, that is, at a constant pitch in the circumferential direction. And form a groove between each ratchet pawl.

  Further, the third lower punch 5 shapes the inner peripheral surface of the cylindrical body portion 11 and the inner end surface of the inner flange 14 of the component, and the core rod 6 shapes the central axial hole 13 of the inner flange 14.

  Further, the upper punch 7 forms the other end surface of the cylindrical body including the other end surface of the thickness increasing portion 16 and the outer surface of the inner flange 14.

  FIG. 2 shows a state in which the raw material powder P is fed into the cavity of the powder molding die 1 and the state of supplying powder is completed.

  The space formed between the die 2 and the third lower punch 5 is wider by the thickness equivalent of the first lower punch 3 as compared with the molding in the state where the thickness increasing portion 16 is not provided. Therefore, the filling property of the raw material powder to the space is improved.

  When the powder supply is completed, the upper punch 7 is driven, the die 2 and the third lower punch 5 are lowered to the fixed position, and the upper punch 7 reaches the lower dead center to complete the compression (see FIG. 3).

  Thereafter, the die 2 and the core rod 6 are first pulled down while the first lower punch 3 supports the molded body 15, and the core rod 6 is pulled out of the axial hole 13 of the molded body (see FIG. 4). The lower punch 5 is pulled down, and the die 2 is subsequently pulled down so that the die 2 and the third lower punch 5 come out of the compact (see FIG. 5).

  Finally, the second lower punch 4 formed on the surface having the ratchet claw 12 of the molded body is pulled down to complete the kicking (extraction) of the molded body from the mold.

  Since the molded body 15 obtained in this manner is in a state in which the ratchet claw 12 is reinforced by the thickened portion 16, a defect such as chipping of the ratchet claw 12 does not easily occur in handling before sintering.

  The compact is then introduced into a sintering furnace and sintered. In the sintering step, since the thickness of the cylindrical body portion is increased by the provision of the thickness-increasing portion, distortion due to sintering can also be suppressed.

  About the blank material of the sintered part obtained through a sintering process, sizing for distortion correction is given as needed.

  After that, the thickened portion of the outer periphery of the blank material is machined off (removal of the thickened portion is possible by turning), and if necessary, the inner circumferential surface of the cylindrical body portion is also machined. It is processed to obtain a finished cylindrical sintered part.

  By the method of the embodiment described above, height: 45 mm, cylindrical body diameter: 75 mm, cylindrical body thickness: 3.0 mm, inner flange thickness: 10 mm, axial hole diameter at the center of the inner flange: 40 mm, ratchet claw A cylindrical sintered part made of an iron-based alloy having a height of 5 mm was produced.

The thickness of the thickness-increasing part provided on the outer periphery of the cylindrical body of the molded body was 2.5 mm. In addition, molding of the powder was performed by applying a molding pressure of 220 Ton, and the molding density of the molded body was 6.9 g / cm ³ .

  As a result of visually inspecting a molded body (the number of samples: 300) obtained by molding under the conditions, no cracking or chipping of the ratchet claw occurred.

  After this, the compact was sintered, and the blank of the obtained sintered part was further turned with a lathe to remove the thickened portion of the outer periphery of the cylindrical body.

  As a result, a product satisfying the required characteristics was obtained, and it was confirmed that powder metallurgical manufacturing of cylindrical parts having unevenness with low strength at the end faces which was conventionally considered difficult was possible.

DESCRIPTION OF SYMBOLS 1 powder molding die 2 die 3 first lower punch 4 second lower punch 5 third lower punch 6 core rod 7 upper punch 10 cylindrical part 11 cylindrical body part 12 ratchet claw 13 axial hole 14 inner flange 15 molding Body 16 Thickened part P Raw material powder

Claims (4)

A manufacturing method of a sintered part having unevenness at one end of a cylindrical body, wherein the thickness of the cylindrical body is made all around the outer periphery or the inner periphery of the cylindrical body in the step of forming the raw material powder. Integrally form an increase in thickness to be increased
The compact obtained after powder compression is supported by a first lower punch formed by molding one end face of the increased thickness portion, and under this condition, other mold elements except the first lower punch and the upper punch Pull the mold out of the mold, and
After that, the method for producing a cylindrical sintered part obtains a target sintered part by sintering the compact and further removing the thickened portion by machining.   The thickened portion is provided on the outer periphery of the cylindrical body portion, and in the step of forming the raw material powder, the outer peripheral surface of the thickened portion is a die, and one end face of the thickened portion is the first lower punch, the cylinder The unevenness on one end of the cylindrical body is a second lower punch, and the inner peripheral surface of the cylindrical body is a third lower punch or core rod, and the other cylindrical body including the other end face of the thickened portion The manufacturing method of the cylindrical sintered component of Claim 1 which shape | molds an end surface with an upper punch, respectively.   The thickness-increasing section is provided on the inner periphery of the cylindrical body section, and in the step of forming the raw material powder, the outer peripheral surface of the cylindrical body section is a die, and one end face of the thickness-increasing section is the first lower punch, The unevenness of one end of the cylindrical body portion is a second lower punch, the inner peripheral surface of the thick portion is a third lower punch or core rod, and the other end face of the thick portion is included. The manufacturing method of the cylindrical sintered component of Claim 1 which shape | molds another end surface by an upper punch, respectively.   The method for manufacturing a cylindrical sintered part according to any one of claims 1 to 3, wherein a sintered part having a thickness of 5 mm or less of the cylindrical body portion is manufactured.

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