CN107138673B

CN107138673B - Cold extrusion overflow forming process of oil pump cover plate

Info

Publication number: CN107138673B
Application number: CN201710516921.7A
Authority: CN
Inventors: 张宇晖
Original assignee: TAICANG JIUXIN PRECISION MOLD CO Ltd
Current assignee: TAICANG JIUXIN PRECISION MOLD CO Ltd
Priority date: 2017-06-29
Filing date: 2017-06-29
Publication date: 2020-04-28
Anticipated expiration: 2037-06-29
Also published as: CN107138673A

Abstract

The invention discloses a cold extrusion overflow forming process of an oil pump cover plate, which comprises the following steps: 1) sequentially carrying out blanking, annealing, shot blasting and surface lubrication treatment on the blank; 2) and putting the blank into a die, performing cold extrusion and overflow one-step forming to manufacture the oil pump cover plate forge piece with one surface provided with the spiral oil groove, the other surface provided with the deep groove and the periphery provided with the flash. The adopted mould comprises: the upper die comprises a punch head, and an overflow groove is circumferentially arranged on the outer wall of the end part of the punch head; the lower die comprises an outer ring, an inner ring, an outer die core and an inner die core which are in interference fit in sequence, and the inner die core comprises an inner die core seat and a plurality of inserts embedded in the inner die core seat; the ejection rod is in interference fit with the inner mold core seat and is used for ejecting the formed oil pump cover plate forge piece; and after the upper die and the lower die are closed, a cavity matched with the oil pump cover plate is formed. The invention adopts a split type die to realize one-step cold extrusion forming, and simultaneously, the invention is matched with overflow forming, thereby greatly prolonging the service life of the die.

Description

Cold extrusion overflow forming process of oil pump cover plate

Technical Field

The invention relates to the technical field of cold forging precision forming, relates to a cold extrusion process, and particularly relates to a cold extrusion overflow forming process of an oil pump cover plate.

Background

The oil pump cover plate is a common engine fitting, mainly provides sufficient fuel for the engine during working, and has high requirements on hardness and strength. Because the shape and the inner cavity of the oil pump cover plate are in a special shape, the forming process is complex. The conventional integral die has long service life and is unstable, and only a multi-time blank making mode (namely, multi-time forming after pre-forging and distributing materials) can be adopted, so that although the early failure of the die is delayed, expensive intermediate treatment cost is generated, such as: intermediate softening treatment and lubricating treatment after multiple times of forming. In addition, the complex process results in longer production period, more process monitoring, occupation of a large amount of manpower and material resources, and management and inconvenience.

In view of the above-mentioned drawbacks, the present inventors have actively studied and innovated to create a cold extrusion overflow forming process for an oil pump cover plate, so that the process skips the intermediate pre-forming process, thereby greatly shortening the manufacturing cycle, reducing the management cost, and having industrial utility value.

Disclosure of Invention

The invention aims to provide a cold extrusion overflow forming process of an oil pump cover plate, which can realize one-step cold extrusion forming, has simple working procedure, saves intermediate softening and lubricating treatment, greatly shortens the manufacturing period, is convenient to manage, is easy to realize automatic production and greatly reduces the cost.

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

a cold extrusion overflow forming process of an oil pump cover plate comprises the following steps:

1) sequentially carrying out blanking, annealing, shot blasting and surface lubrication treatment on the blank;

2) and putting the blank into a die, closing the die, performing cold extrusion and overflow one-step forming, and manufacturing the oil pump cover plate forge piece with one surface provided with the spiral oil groove, the other surface provided with the deep groove and the periphery provided with the flash.

Further, the annealing in the step 1) adopts spheroidizing annealing, and specifically comprises the following steps:

during the annealing treatment, the temperature is heated to 380-400 ℃, the heat preservation is carried out for 5-6h, then the temperature is reduced to 250 ℃ along with the furnace, the heat preservation is carried out for 4-5h, and then the product is taken out of the furnace and cooled to the room temperature.

Further, the surface lubrication treatment in the step 1) is performed by using zinc stearate or a polymer lubricant.

Further, the blank is an aluminum alloy.

Further, the height of the flash of the oil pump cover plate forging is 3mm relative to the oil pump cover plate forging.

Further, the mold comprises:

the upper die comprises a punch head, and an overflow groove is circumferentially arranged on the outer wall of the end part of the punch head;

the lower die comprises an outer ring, an inner ring, an outer die core and an inner die core which are in interference fit in sequence from outside to inside, and the inner die core comprises an inner die core seat and a plurality of inserts embedded in the inner die core seat; and

the ejection rod penetrates through the inner die core seat and is in interference fit with the inner die core seat, and the ejection rod is used for ejecting the formed oil pump cover plate forge piece;

and after the upper die and the lower die are assembled, a cavity matched with the oil pump cover plate is formed.

Furthermore, the outer mold core is provided with a through hole in interference fit with the inner mold core, one end of the through hole is a feeding hole, the feeding hole is in a horn mouth shape with a wide upper part and a narrow lower part, and the feeding hole and the rest of the through hole are in arc surface transition.

Furthermore, the inner die core seat is in interference fit with three ejector rods.

Further, the height of the overflow groove is 3 mm.

Further, in the step 2), the upper die is fixed on an upper die base of a press, the lower die is fixed on a lower die base of the press, and the blank is placed between the upper die and the lower die; then the upper die holder drives the upper die to move downwards, the upper die contacts the blank firstly, moves downwards and starts to form, and the blank is continuously pressed for a certain distance until the blank is completely formed; and after the pressing action is finished, the return stroke of the press is finished, and the oil pump cover plate forge piece with a spiral oil groove on one side, a deep groove on the other side and fins on the periphery is ejected out of the ejector rod.

The invention has the beneficial effects that:

1. the process adopts one-step cold extrusion overflow forming, achieves the effect of one-step forming, has high forging precision and simple working procedure, saves intermediate softening and lubricating treatment, greatly shortens the manufacturing period, has simple production process, is convenient to manage, is easy to realize automatic production and greatly reduces the cost;

2. the T6 heat treatment can be directly carried out in the subsequent process, other intermediate treatment links are not needed, the product quality is stable, and the production efficiency is high;

3. the overflow forming mode is adopted during forming, the metal flow is optimized, the forming force is reduced, and meanwhile, the service life of the die can be greatly prolonged through the overflow groove;

4. the weight requirements for the billet are also greatly relaxed due to the presence of the isopipe.

Drawings

FIG. 1 is a schematic diagram of a cold extrusion overflow forming process for an oil pump cover plate according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a mold used in a cold extrusion overflow forming process of an oil pump cover plate according to an embodiment of the present invention;

FIG. 3 is a schematic structural view of an oil pump cover plate forging after being formed by the forming process of the invention;

FIG. 4 is a schematic structural view of an upper die of the mold;

FIG. 5 is a structural sectional view of a lower die of the mold;

FIG. 6 is a sectional view showing the structure of an outer core in the lower mold;

fig. 7 is a partially cut-away perspective view of the inner core of the lower mold.

In the figure: 10-upper die, 11-overflow groove, 21-outer ring, 22-inner ring, 23-outer die core, 24-inner die core, 25-inner die core seat, 26-insert, 27-through hole, 28-feeding hole, 29-cambered surface, 30-ejector rod, 40-forge piece, 41-flash and 50-fixed hole.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The front surface and the back surface of the oil pump cover plate related by the invention are both in special shapes, wherein two circles of asymmetrical oil grooves are arranged on the front surface, special-shaped deep grooves are arranged on the back surface, and the depth of the special-shaped deep grooves exceeds that of the front surface.

As shown in fig. 1, in the cold extrusion overflow forming process of the oil pump cover plate of the present invention, in a first step S1, a blank is blanked; step S2, performing pretreatment on the blank, wherein the pretreatment comprises annealing, shot blasting and surface lubricating treatment; and step S3, placing the blank into the die of FIG. 2, closing the die, performing cold extrusion and overflow one-step forming, and manufacturing the oil pump cover plate forging 40 with two asymmetric spiral oil grooves on one surface, a deep groove on the other surface and flash on the periphery. The formed oil pump cover plate forging is as shown in fig. 3, the height of the flange 41 of the oil pump cover plate forging is 3mm relative to the oil pump cover plate forging, the flange 41 can effectively improve the flowing of a blank in forming, the forming load is greatly reduced, and the service life of a die is prolonged; meanwhile, the weight control during blanking is greatly relaxed.

Specifically, the oil pump cover plate blank is 6028 aluminum alloy, spheroidizing annealing is adopted, the temperature is heated to 380-400 ℃ during annealing treatment, the heat is preserved for 5-6h, then the temperature is reduced to 250 ℃ along with the furnace, the heat is preserved for 4-5h, and then the oil pump cover plate blank is taken out of the furnace and cooled to room temperature in air; then carrying out conventional shot blasting treatment; and finally, performing surface lubrication treatment by adopting zinc stearate or a high-molecular lubricant.

Therefore, the process of the invention adopts one-step cold extrusion overflow forming, achieves the effect of one-step forming, has high forging precision and simple working procedure, saves intermediate softening and lubricating treatment, greatly shortens the manufacturing period, has simple production process, is convenient to manage, is easy to realize automatic production and greatly reduces the cost; the process can directly carry out T6 heat treatment subsequently without other intermediate treatment links, and has stable product quality and high production efficiency.

As shown in fig. 2 and 4 to 7, the die for cold extrusion and overflow forming of a billet comprises: the upper die 10 comprises a punch head, and an overflow groove 11 is circumferentially arranged on the outer wall of the end part of the punch head; the lower die comprises an outer ring 21, an inner ring 22, an outer die core 23 and an inner die core 24 which are in interference fit in sequence from outside to inside, and the inner die core 24 comprises an inner die core seat 25 and a plurality of insert pieces 26 embedded in the inner die core seat; the ejector rod 30 penetrates through the inner die core seat 25 to be in interference fit with the inner die core seat 25, and is used for ejecting the formed oil pump cover plate forge piece 40; wherein, after the upper die and the lower die are combined, a cavity for forming the oil pump cover plate is formed.

Specifically, the outer mold core 23 is provided with a through hole 27 in interference fit with the inner mold core 24, one end of the through hole 27 is a feeding port 28, the feeding port 28 is in a bell mouth shape with a wide upper part and a narrow lower part, and the feeding port 28 and the rest of the through hole 27 are in transition of an arc surface 29. The feeding port 28 is designed to be in a horn mouth shape with a wide upper part and a narrow lower part, when the punch presses the blank downwards, the blank can smoothly enter the through hole 27 below the feeding port 28 from the feeding port 28, and the friction force of the blank entering the through hole 27 can be greatly reduced due to the transition of the feeding port and the rest part of the through hole 27 of 28 by the cambered surface 29.

In order to smoothly eject the oil pump cover plate forge piece, the inner die core seat 25 is in interference fit with three ejector rods 30, and the oil pump cover plate forge piece is ejected out from three points simultaneously by using the three ejector rods; in addition, the ejector rod 30 and the inner mold core 24 adopt a small interference mode, so that material drilling can be effectively prevented.

In order to overflow the 3mm flash 41 at the periphery of the oil pump cover plate forging 40 at the time of cold extrusion, the height of the overflow groove 11 was also set to 3 mm.

In order to facilitate the installation of the mold on the press, fixing holes 50 for fixing the lower mold to the press are provided in both the outer ring 21 and the inner mold core holder 25.

When the die is used for cold extrusion overflow forming of the oil pump cover plate forge piece, the upper die 10 is fixed on an upper die base of a press, and the lower die is fixed on a lower die base of the press. When the oil pump cover plate forging is extruded, a blank is placed between the upper die 10 and the lower die, the upper die base drives the upper die to move downwards, the upper die contacts the blank firstly, continues to move downwards and starts to be formed. The risk of blocking during forming is avoided, excess material flows into the overflow channel 11, and due to the asymmetry of the forging, sufficient free surface also optimizes material flow to a great extent. After pressing in for a distance, the forming is substantially complete. Due to the overflow groove 11, even if the press has stroke deviations of different degrees, the risk of cracking of the upper die can be greatly reduced; even if the blank has different weight deviations, the mold can be protected by the existence of the overflow groove 11. After the pressing action is finished, the return stroke of the press is finished, the three ejector rods 30 eject the forged piece, due to the existence of the overflow groove 11, the flange 41 with enough height is arranged at the outer circle of the forged piece 40, the automatic carrying can be easily realized, the safety and the reliability are realized, and the whole forming process is finished.

Compared with the prior multiple preform preparation process, the invention has the following advantages: the one-step cold extrusion molding is adopted, the process is simple, the softening and lubricating treatment among stations is omitted, and the manufacturing period is greatly shortened; the overflow forming mode has the advantages of long service life of the die, small load, great relaxation of the requirement on the weight of the blank, simple production process, convenient management, easy realization of automatic production and great reduction of cost; the subsequent T6 heat treatment is directly carried out, the product quality is stable, and the production efficiency is high.

Compared with the traditional integral die, the split die (mainly the lower die is split) has high strength and long service life, can form the oil pump cover plate forge piece at one time, skips the intermediate preforming process, greatly shortens the manufacturing period and reduces the management cost.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims

1. A cold extrusion overflow forming process of an oil pump cover plate is characterized by comprising the following steps:

2) placing the blank into a die, performing cold extrusion and overflow one-step forming to manufacture an oil pump cover plate forge piece with a spiral oil groove on one surface, a deep groove on the other surface and fins on the periphery;

the mold comprises: the upper die comprises a punch head, and an overflow groove is circumferentially arranged on the outer wall of the end part of the punch head; the lower die comprises an outer ring, an inner ring, an outer die core and an inner die core which are in interference fit in sequence from outside to inside, and the inner die core comprises an inner die core seat and a plurality of inserts embedded in the inner die core seat; the ejection rod penetrates through the inner die core seat and is in interference fit with the inner die core seat, and the ejection rod is used for ejecting the formed oil pump cover plate forge piece; after the upper die and the lower die are assembled, a cavity for forming the oil pump cover plate is formed;

the outer mold core is provided with a through hole in interference fit with the inner mold core, one end of the through hole is a feeding hole, the feeding hole is in a horn mouth shape with the upper part wide and the lower part narrow, and the feeding hole and the rest parts of the through hole are in cambered surface transition.

2. The cold extrusion overflow forming process of the oil pump cover plate according to claim 1, wherein the annealing in the step 1) adopts spheroidizing annealing, and specifically comprises the following steps:

3. The cold extrusion overflow forming process of the oil pump cover plate according to claim 1, wherein the surface lubrication treatment in the step 1) is performed by using zinc stearate or a high molecular lubricant.

4. A process for cold extrusion overflow forming of an oil pump cover plate according to any one of claims 1 to 3, wherein the blank is an aluminum alloy.

5. The cold extrusion overflow forming process of an oil pump cover plate according to claim 1, wherein the height of the flash of the oil pump cover plate forging relative to the oil pump cover plate forging is 3 mm.

6. The process of claim 1, wherein three ejector pins are interference fitted to the inner die holder.

7. The cold extrusion overflow forming process of an oil pump cover plate according to claim 1, wherein the height of the overflow groove is 3 mm.

8. The cold extrusion overflow forming process of the oil pump cover plate according to claim 7, wherein in the step 2), the upper die is firstly fixed on an upper die base of a press, the lower die is fixed on a lower die base of the press, and the blank is placed between the upper die and the lower die; then the upper die holder drives the upper die to move downwards, the upper die contacts the blank firstly, moves downwards and starts to form, and the blank is continuously pressed for a certain distance until the blank is completely formed; and after the pressing action is finished, the return stroke of the press is finished, and the oil pump cover plate forge piece with a spiral oil groove on one side, a deep groove on the other side and fins on the periphery is ejected out of the ejector rod.