CN222198350U - Cold extrusion forming die for forming special-shaped internal spline shaft by tube blank - Google Patents

Abstract

The utility model discloses a cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank, which comprises an upper die and a lower die which are coaxially arranged, wherein a blank is placed into a die cavity of the special-shaped internal spline cold extrusion die, a tooth punch is driven to extrude the blank by utilizing downward movement of an oil press to obtain the special-shaped internal spline shaft, and a lower ejector rod is moved upwards to eject the special-shaped internal spline shaft from the die cavity. The special-shaped internal spline is cold extruded by adopting oil press equipment, so that the overall cost is reduced, the straightness of the extruded special-shaped internal spline is the same as that of radial forging, the mechanical strength of the tooth form is improved, and the production efficiency is high.

Description

Cold extrusion forming die for forming special-shaped internal spline shaft by tube blank

Technical Field

The utility model relates to the field of machining equipment for manufacturing, in particular to a cold extrusion forming die for a tube blank forming special-shaped internal spline shaft.

Background

Spline shafts are commonly used in aircraft, automotive, tractor, machine tool manufacturing, agricultural machinery, and general mechanical transmissions. The spline shaft has high bearing capacity, good neutrality and guiding performance, and small stress concentration due to the shallow tooth root.

The spline is one kind of mechanical transmission, and like flat key, half key and inclined key, it is all to transmit mechanical torque, and there is longitudinal keyway on the outward appearance of axle, and the rotating member that overlaps on the axle also has corresponding keyway, can keep rotating with the axle in step. While rotating, some may also slide longitudinally on the shaft, such as a gearbox shift gear or the like. The spline shaft is mainly applied to a brake and a steering mechanism, and also comprises a telescopic shaft which is composed of an inner pipe and an outer pipe, wherein the outer pipe is provided with internal teeth, and the inner pipe is provided with external teeth and sleeved together. When in use, the rotary torque is transmitted, and the telescopic device can extend and retract in the length direction. The spline connection is formed by a shaft with a plurality of longitudinal key teeth and a hub, and corresponds to an external spline and an internal spline.

A spline shaft in the prior art is formed by radial forging, for example, a molding method of casting a tooth profile and a molded article disclosed in japanese patent JP2012196695A, by placing a rough material in a mold and then pressing a spline punch into the rough material to mold a spline bearing in an inner peripheral portion of a pulley. Clearance grooves are formed in advance in the material while being adjacent to spline holes formed in the spline bearing. When forging is performed, both axial ends of the spline hole are held so that the plastically flowing material flows into the clearance groove, and therefore, the spline bearing and both ends thereof can be molded with high dimensional accuracy while preventing an excessive rise in internal pressure of the mold, thereby eliminating machining after forging, since radial forging forming is an inlet device, the structural complexity is high, the exclusive use is high, the cost is high, and the cost is relatively high.

For example, chinese patent CN 105013844A discloses an internal spline cold extrusion device for an automobile steering pump shaft, which consists of an oil press and a die, wherein the die comprises an upper die and a lower die, the upper die is arranged on an upper working platform of the oil press, an internal spline punch matched with an inner hole of a part is arranged below the upper die, the lower die is arranged on a lower working platform of the oil press, a die cavity matched with an outer circle of the part is arranged at the center of the lower die, and the centers of the internal spline punch and the die cavity are on the same straight line.

Disclosure of utility model

The utility model aims to solve the defects of the prior art and provide a cold extrusion forming die for a tube blank forming special-shaped internal spline shaft, which adopts oil press equipment to cold extrude special-shaped internal splines, so that the cost is reduced, the straightness of the extruded special-shaped internal splines is the same as that of radial forging, the tooth-shaped mechanical strength is improved, and the production efficiency is high.

In order to achieve the purpose, the cold extrusion forming die for forming the special-shaped internal spline shaft of the tube blank comprises an upper die and a lower die which are coaxially arranged, a blank is placed into a die cavity of the special-shaped internal spline cold extrusion die, a tooth punch is driven to extrude the blank by utilizing downward movement of an oil press to obtain the special-shaped internal spline shaft, and a lower ejector rod is moved upwards to eject the special-shaped internal spline shaft from the die cavity;

The upper die comprises: the device comprises a punch sleeve, an outer punch transition sleeve, an outer punch, a tooth punch transition sleeve, a tooth punch, a punch cushion block, an upper template, an upper lock nut and an upper die barrel, wherein the punch cushion block is arranged in the punch sleeve;

The lower die comprises a female die A, a female die B and a female die C which are coaxially arranged and sequentially abutted, wherein the female die B and the female die C are of a three-layer stress sleeve structure, the female die B and the female die C are sleeved on the female die A, the female die B and the female die C are radially and externally fixed on female die cushion blocks positioned on the axial end faces of the female die B and the female die C through pressing plates, a lower die barrel is sleeved on the radially and externally sides of the female die sleeve and the female die cushion blocks, a lower locking nut is sleeved on the radially and externally side of the lower die barrel, the lower die barrel is vertically fixed on a lower die plate, and a lower ejection rod is arranged on the female die cushion blocks and the lower die plate in a penetrating mode.

In the second step, the deformation of the blank is controlled within 60%, the unit pressure of the punch is not more than 2500Mpa, the deformation of the extruding teeth is mainly defined by the radial dimension of the outer circle of the blank, and the deformation of the extruding teeth is adjusted by adjusting the radial dimension of the outer circle of the blank. The inner hole size of the blank is determined according to the inner hole size of the forging piece;

as a further preferable mode of the invention, in the second step, the outer circle of the blank is The tolerance is controlled to be 0-0.05 mm, and the size of the inner hole of the blank is controlled to be 0-0.05 mmAnd the tolerance of the upper and lower differences of the maximum inner hole step size of the forging piece is controlled to be 0-0.05 mm.

In the sixth step, the lower end surface of the tooth punch exceeds the die working belt, so that the blank flows downwards along the tooth punch and the die A working belt during extrusion deformation, when the tooth punch moves downwards, the top end surface of the tooth punch is not contacted with the tooth punch cushion block due to dead weight when the tooth punch does not contact the blank, and when the tooth punch enters the inner hole of the blank, the gap between the tooth punch and the inner hole of the blank is far smaller than the accumulated gap between the press and the die frame, so that the tooth punch smoothly passes through the inner hole of the blank, and a circumferential and axial gap is arranged, so that the tooth punch can be aligned with the center and move up and down and shake circumferentially in the tooth punch transition sleeve.

In a further preferred embodiment of the present invention, in the sixth step, a plurality of small holes for locking the punch sleeve are uniformly formed on the radial outer side of the upper lock nut, and the rod inserted into the small holes rotates the upper lock nut clockwise and counterclockwise.

In the sixth step, a plurality of small holes for locking the female die sleeve and the lower die barrel are uniformly formed on the radial outer side of the lower locking nut, and the rod inserted into the small holes rotates the lower locking nut clockwise and anticlockwise.

In a further preferred aspect of the present invention, in the sixth step, a gap is provided between the end face of the tooth punch and the punch pad. The purpose of the gap is that when the tooth punch enters the inner hole of the tube blank and the special-shaped internal spline is formed by extrusion, the tooth punch is automatically found out, and is not easy to break.

When the tooth punch head moves downwards, the top end face of the tooth punch head is not contacted with the tooth punch head cushion block due to dead weight, and when the tooth punch head enters the inner hole of the tube blank, the gap between the tooth punch head and the inner hole of the tube blank is far smaller than the accumulated gap between the press and the die carrier, so that the tooth punch head smoothly passes through the inner hole of the tube blank, a circumferential and axial gap is arranged, the tooth punch head can be aligned to the center, and the tooth punch head can move up and down and shake circumferentially in the transition sleeve of the tooth punch head.

In the sixth step, the lower end surface of the inner hole of the female die a is provided with a sealing opening, and the inner hole opening of the upper end surface of the female die B is also provided with the same sealing opening, so that the end surfaces of the female die a and the female die B are tightly attached after being assembled, and the material leakage is not easy in the extrusion process.

In a further preferred embodiment of the present invention, in the sixth step, a gap is provided between the outer punch and the outer punch transition sleeve, and a gap is provided between the tooth punch and the tooth punch transition sleeve, wherein the gap is 1mm.

In a further preferred embodiment of the present invention, in the sixth step, a gap is provided between the outer punch and the punch sleeve, a gap is provided between the outer punch and the outer punch transition sleeve, a gap is provided between the tooth punch transition sleeve and the punch sleeve, and a gap is provided between the tooth punch and the tooth punch transition sleeve. The outer punch transition sleeve is sleeved with the bilateral 0.03-0.07 mm of the inner assembly gap of the punch sleeve, the outer punch is sleeved with the bilateral 2mm of the inner assembly gap of the outer punch transition sleeve, the tooth punch transition sleeve is sleeved with the bilateral 0.03-0.07 mm of the inner assembly gap of the punch sleeve, and the tooth punch is sleeved with the bilateral 2mm of the inner assembly gap of the tooth punch transition sleeve.

The cold extrusion forming die for the special-shaped internal spline shaft for tube blank forming has the advantages that compared with the prior art, the cold extrusion forming die for the special-shaped internal spline shaft for tube blank forming has the following advantages:

(1) The upper die assembly and the forming female die adopt die orifice guiding, so that concentricity of the forged piece after being formed by the upper die and the lower die is ensured;

(2) The die structure adopts a three-layer prestress structure, the die strength is high, and in addition, the middle ring adopts a hard alloy material, so that the forgings are ejected out after being formed, the dimensional stability of the forgings is ensured, and the service life of the die is greatly prolonged;

(3) The product obtained by the die has high precision and low rejection rate, reduces the overall cost and lightens the pressure of input cost.

Drawings

FIG. 1 is a full cross-sectional view of a blank after being placed into a cold extrusion die for a profiled internal spline;

FIG. 2 is a partial enlarged view;

FIG. 3 is a full cross-sectional view of a cold extrusion die for a profiled internal spline during forging formation;

FIG. 4 is a schematic view of the structure of a blank;

Fig. 5 is a schematic diagram of the finished product after cold extrusion is completed.

Detailed Description

The invention is further elucidated below in conjunction with the drawings.

As shown in fig. 1, a blank is placed into a die cavity of a special-shaped internal spline cold extrusion die, a tooth punch 15 is driven to extrude the blank by using an oil press to move downwards to obtain a special-shaped internal spline shaft, a lower ejector rod 27 moves upwards to eject the special-shaped internal spline shaft from the die cavity, and the special-shaped internal spline cold extrusion die comprises an upper die and a lower die which are coaxially installed;

The upper die comprises a punch sleeve 11, an outer punch transition sleeve 12, an outer punch 13, a tooth punch transition sleeve 14, a tooth punch 15, a punch cushion block 16, an upper die plate 17, an upper lock nut 18 and an upper die barrel 19, wherein the punch cushion block 16 is arranged in the punch sleeve 11, after the outer punch 13 is sleeved outside the tooth punch 15, the end part of the tooth punch 15 is fixed in the punch sleeve 11 through the tooth punch transition sleeve 14, the end part of the outer punch 13 is fixed on the punch sleeve 11 through the outer punch transition sleeve 12, the punch sleeve 11 is fixed on the upper die plate 17 through the upper die barrel 19, and the upper lock nut 18 arranged on one side of the axial direction of the upper die barrel 19 is sleeved on the punch sleeve 11;

The lower die comprises a female die A21, a female die B23, a female die C24, a female die sleeve 22 sleeved on the radial outer sides of the female die A21, the female die B23 and the female die C24, a female die cushion block 26 positioned on the axial end surfaces of the female die sleeve 22 and the female die C24 is fixed with the female die sleeve 22 through a pressing plate 25, a lower die barrel 28 is sleeved on the radial outer sides of the female die sleeve 22 and the female die cushion block 26, a lower locking nut 20 is sleeved on the radial outer sides of the lower die barrel 28, the lower die barrel 28 is vertically fixed on a lower die plate 29, and a lower ejection rod 27 is arranged on the female die cushion block 26 and the lower die plate 29 in a penetrating manner.

Examples

Step one, blanking

Selecting blanks with single-side machining allowance of 1mm according to the sizes of the outer circle and the inner hole, and sawing the steel pipe into the corresponding length by using a circular saw according to the blanking length;

Step two, turning

According to the size requirement of the blank, the excircle is arrangedInner boreTurning the length dimension L in place, and according to the weight C of the forge piece, turning the blank length L according to the excircle of the blankAnd an inner boreThe method comprises the following steps:

the deformation of the blank is controlled within 60 percent, and the unit pressure of the punch is not more than 2500Mpa, and the excircle of the blank is satisfied The tolerance is controlled to be 0-0.05 mm, and the size of the inner hole of the blank is controlled to be 0-0.05 mmThe tolerance of the upper middle difference of the maximum inner hole step size of the forging piece is controlled to be 0-0.05 mm;

Step three, spheroidizing annealing

Heating the turned blank in an annealing furnace to 730-740 ℃ for heat preservation for 2-3 hours, and then slowly cooling to 650 ℃ at a speed of less than 20 ℃/h, and discharging;

Step four, sand blasting

The outer circle and the inner hole of the blank after spheroidizing are subjected to sand blasting treatment to remove oxides generated by spheroidizing annealing, micro concave-convex textures can be formed on the surface of the blank, the surface area of the blank is increased, and the area of a coating at the back is increased

Step five, surface treatment

Placing the sand-blasted blank into phosphorus saponification pretreatment liquid to make phosphorus saponification coating treatment on the surface of the blank so as to reduce friction force when metal flows, and make forging easier to form

Step six, extruding special-shaped internal spline

The outer punch 13 and the tooth punch 15 are driven to move downwards together by the aid of an oil press through a press sliding block, the tooth punch 15 firstly penetrates through an inner hole of a blank, then the outer punch 13 enters the die B die core 233 until the outer punch 13 is in contact with the end face of the blank, at the moment, the lower end face of the tooth punch 15 exceeds the die B die core 233, the blank flows downwards along the working belt of the tooth punch 15 and the die A21 during extrusion deformation, the outer punch 13 pushes the blank to move downwards continuously, the blank forms special-shaped internal splines through the die B die core 233 and the tooth punch 15, and the tooth punch 15 moves downwards along with the blank until the blank is extruded to a required length of a forging to obtain a finished product. The press sliding block retreats upwards to drive the outer punch 13 and the tooth punch 15 to move upwards together, so that the tooth punch 15 is completely separated from the inner hole of the forging piece to return to the upper limit position of the press sliding block, the machine tool ejector rod pushes the lower ejector rod 27 to move upwards to push the forging piece out of the female die, and the forging piece is taken out and put into the material frame manually.

The female die A21 comprises a female die A shell 211, a female die A middle ring 212 and a female die A die core 213, the female die A shell 211, the female die A middle ring 212 and the female die A die core 213 are in interference fit with each other by large-pressure and large-pressure, a guide section is arranged at the inner orifice part, so that an outer punch can smoothly enter a female die inner hole, the female die A21 mainly plays a role in storing blanks and guiding the outer punch, and the diameter of the inner hole is about 0.1mm larger than that of the blanks, so that the blanks can be conveniently placed in a female die cavity. The lower end face of the inner hole of the female die A21 is provided with a sealing port 100, and the inner hole of the upper end face of the female die B23 is also provided with the same sealing port 100, so that the end faces of the female die A21 and the female die B23 are tightly attached after being assembled, and material leakage is not easy in the extrusion process.

The female die B23 adopts a three-layer stress sleeve structure and comprises a female die B shell 231, a female die B middle ring 232 and a female die B die core 233, the female die B shell 231, the female die B middle ring 232 and the female die B die core 233 are in interference fit with large-pressure and large-pressure quantities, the female die B die core 233 is made of hard alloy materials, the strength is high, the wear resistance is good, the mouth size of the female die B23 is the same as the inner hole size of the female die A21, a die entering angle, a working belt and a hollow section are arranged below the mouth size of the female die B23, the diameter of the inner hole of the working belt is the outer circle size of a forging piece, and the special-shaped inner spline and the outer circle can be formed by the materials along the working belt and the tooth punch. The diameter of the penetrating segment is 0.4-0.5 mm larger than that of the inner hole of the working belt, and the forming force can be reduced.

The female die C24 adopts a two-layer stress sleeve structure and comprises a female die C241 shell and a female die C mold core 242, the female die C shell 241 and the female die C mold core 242 both adopt interference fit with large compression amount, and the inner hole size is the same as the size of the hollow section of the female die B23.

The foregoing embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and to implement the same, not to limit the scope of the present invention. All changes and modifications that come within the meaning and range of equivalency of the invention are to be embraced within their scope.

Claims (8)

1. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank, characterized in that it comprises an upper die and a lower die coaxially mounted; The upper die comprises: a punch sleeve (11), an outer punch transition sleeve (12), an outer punch (13), a tooth punch transition sleeve (14), a tooth punch (15), a punch pad (16), an upper die plate (17), an upper locking nut (18) and an upper die barrel (19); the punch pad (16) is installed in the punch sleeve (11); after the outer punch (13) is sleeved on the outer side of the tooth punch (15), the end of the tooth punch (15) is fixed in the punch sleeve (11) through the tooth punch transition sleeve (14); the end of the outer punch (13) is fixed on the punch sleeve (11) through the outer punch transition sleeve (12); the punch sleeve (11) is fixed on the upper die plate (17) through the upper die barrel (19); and the upper locking nut (18) provided on one side of the axial direction of the upper die barrel (19) is sleeved on the punch sleeve (11); The lower die comprises: a die A (21), a die B (23), and a die C (24) which are coaxially arranged and closely adjacent to each other, a die sleeve (22) which is sleeved on the radially outer sides of the die A (21), the die B (23), and the die C (24), the die sleeve (22) being fixed on a die pad (26) located on the axial end faces of the die sleeve (22) and the die C (24) by a pressing plate (25), a lower die barrel (28) being sleeved on the radially outer sides of the die sleeve (22) and the die pad (26), a lower locking nut (20) being sleeved on the radially outer sides of the lower die barrel (28), the lower die barrel (28) being vertically fixed on a lower mold plate (29), and a lower ejector rod (27) being passed through the die pad (26) and the lower mold plate (29). 2. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 1, characterized in that a gap is provided between the end face of the tooth punch (15) and the punch pad (16). 3. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 2, characterized in that: a plurality of small holes for locking the punch sleeve (11) are evenly arranged on the radial outer side of the upper locking nut (18), and a rod inserted into the small hole rotates the upper locking nut (18) in clockwise and counterclockwise directions. 4. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 1, characterized in that a plurality of small holes for locking the die sleeve (22) and the lower die barrel (28) are evenly arranged on the radial outer side of the lower locking nut (20), and the rods inserted in the small holes rotate the lower locking nut (20) in clockwise and counterclockwise directions. 5. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 1, characterized in that a sealed opening (100) is provided at the lower end surface of the inner hole of the die A (21), and a similar sealed opening (100) is also provided at the inner hole opening of the upper end surface of the die B (23). 6. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 1, characterized in that a gap is provided between the outer punch (13) and the outer punch transition sleeve (12), and a gap is provided between the tooth punch (15) and the tooth punch transition sleeve (14). 7. A cold extrusion forming die for forming a special-shaped internal spline shaft of a tube blank according to claim 1, characterized in that: a gap is provided between the outer punch (13) and the punch sleeve (11), a gap is provided between the outer punch (13) and the outer punch transition sleeve (12), a gap is provided between the tooth punch transition sleeve (14) and the punch sleeve (11), and a gap is provided between the tooth punch (15) and the tooth punch transition sleeve (14). 8. A cold extrusion forming die for forming a tube blank into a special-shaped internal spline shaft according to claim 1, characterized in that the upper die plate (17) is connected to a hydraulic press.