CN102350475B

CN102350475B - Material overlapping and cold precision forging technique for straight toothed spur gear

Info

Publication number: CN102350475B
Application number: CN 201110259017
Authority: CN
Inventors: 章建军; 杨程
Original assignee: Xian University of Architecture and Technology
Current assignee: Xian University of Architecture and Technology
Priority date: 2011-09-02
Filing date: 2011-09-02
Publication date: 2013-07-10
Anticipated expiration: 2031-09-02
Also published as: CN102350475A

Abstract

The invention discloses a material overlapping and cold precision forging technique for a straight toothed spur gear, which comprises the steps of: 1) putting two pieces of cylindrical blanks with the same volume in a circular female die along the axial lines thereof in an overlapping manner, overlapping the cylindrical blanks, and primarily extruding the cylindrical blanks; 2) stopping extrusion and taking out the cylindrical blanks if the joining surface of the two cylindrical blanks and the female die is larger than 1/2 of the blank height; 3) exchanging the upper and the lower positions of the two blanks, overlapping the blanks and extruding the blanks again; 4) stopping the extrusion operation if the two blanks are fully joined with the female die and if the tooth forms are fulfilled; and 5) leveling the parts extruded for twice to obtain a final workpiece. The technical can be used for fully filling the material overlapping corner of the straight toothed spur gear under a low extrusion force so that qualified parts are successfully formed by pressing; and the invention has the advantages of forming easiness, filling completeness, simple and reliable mould structure and long service life.

Description

The folded material cold closed-die forging technology of straight spur gear

Technical field

The invention belongs to the cold closed-die forging technology in the machine industry, particularly a kind of folded material forging that is applicable to that straight spur gear is produced.

Background technology

Current, straight spur gear is used maximum processing technologys and is still traditional cutting technology, use forging blank or bar, through car, mill and heat treatment subsequently finally is shaped, this processes is long man-hour, production efficiency is low, waste of material is bigger, and it is more to consume energy, and its economic and social benefit is all relatively poor, and the material fiber with toothed section in working angles cuts off intensity and the service life of having reduced gear.

Along with developing rapidly of industry, the gear part that is used for automobile and aircraft industry requires weight reduction and gains in strength, because the needs of competition also require to reduce cost, the gear finish forge is processed a kind of technology that adapts to this demand just simultaneously.Compare with traditional cutting technology, the gear forging can improve the structure property of gear, has improved the service life of gear, produces the efficient height, and the stock utilization height is good in economic efficiency.

For the less gear of straight spur gear especially ratio of height to diameter, because profile of tooth during finish forge (corner place particularly) filling difficulty, finally cause corner place insufficient fill, the concave die cavity wall will bear very big pressure simultaneously, and there is the stress of height to concentrate, cause the die cracking easily, so the straight spur gear precision forging is more much more difficult than bevel gear, still being in technology at present and exploring and the laboratory research stage, is one of focus of forging technology research both at home and abroad in recent years.

Summary of the invention

The folded material forging that the purpose of this invention is to provide a kind of straight spur gear, this technology is at the difficult point of straight spur gear cold closed-die forging insufficient fill, adopt that two compact material deads in line are superimposed up and down carries out twice extruding, can under much smaller extruding force, successfully suppress qualified parts, have and be shaped easily, advantages such as filling is satisfactory, and extruding force is little, and simple and reliable and life-span of mould structure is long.

The objective of the invention is to realize by following technical proposals.

A kind of folded material cold precision forging technology of straight spur gear, this technology comprises the steps:

1) the long-pending identical cylinder blank of two blocks is placed circular die along its dead in line, and two cylinder blank inner faces contacts are carried out superimposed, push for the first time then; At this moment near the material circular die of will at first the fitting end face that contacts with each other of blank, it is intact that type is filled at profile of tooth corner place;

2) when two cylinder blanks and circular die binding face during greater than 1/2 blank height, stop extruding, two compact material are taken out;

3) then two compact material upper-lower positions are exchanged, put into circular die again, will in first extrusion process, be superimposed with each other with the blank face that following backform pressure head contacts with last backform, push again then;

4) when two compact material and circular die is fully fitted, the profile of tooth filling satisfactory after, stop the extruding;

5) will flatten through the part after twice extruding after, namely get final workpiece.

Further aspect of the present invention is:

Described first extruding, in the starting stage of its distortion, being full of the required stress of corner is the yield stress that blank enters the surrender stage.

Described extruding again in the starting stage of its distortion, is full of the yield stress that the required stress of corner is a bit larger tham first extruding, the yield stress when pushing less than thin material after the sclerosis.

The cold precision forging technology of straight spur gear of the present invention is carried out the contact of two cylinder blank dead in line end faces superimposed, pushes for the first time then, and at this moment material will paste mould earlier near the end face that contacts with each other of blank, and it is intact that type is filled at profile of tooth corner place; After the exchange of two blank upper-lower positions, the end face that is not badly deformed that two blanks originally contacted with the mould pressure head contacts with each other superimposed, the end face that fully had been out of shape in the middle part of originally being in contacts with the mould pressure head, push again, the part that is not badly deformed will fully be out of shape, and so just can obtain the satisfactory part of complete filling; The part that the profile of tooth filling is satisfactory flattens and obtains final workpiece.The essence of this technology is that extrusion molding is carried out at the position that the corner position that is difficult to filling can be with common cold extrusion the time is transformed into easy deformation, can make the filling of flank profil position complete under much lower pressure.

The process that the present invention proposes has following advantage:

1, the flank profil filling is satisfactory.Adopt twice extruding, solved the flank profil corner place difficult problem of filling fully dexterously.

2, resistance of deformation is little, is shaped easily.Because twice extruding all needn't be because of filling corner place intensified pressure, the yield stress when making deformational stress in the whole technology than common extruding or thin material extruding after the sclerosis is little many.

3, mould structure is simple, and the life-span is long.Do not need the idio-morphosis control procedure, only need the simplest deformation process, so mould structure is simple, cost of manufacture is low.

4, process is simple, need not the heating power consumption.Only use prevailing extrusion process, and need not temperature, hot extrusion and also can satisfactoryly fill type, energy-conserving and environment-protective.

Description of drawings

Fig. 1 is the position of blank in mould before the first extruding;

Form when Fig. 2 pushes for the first time for blank;

Fig. 3 is that two blank upper-lower positions exchange the form of back in mould;

Fig. 4 is the final form of blank after the secondary extrusion, and the flank profil filling is complete;

Fig. 5 is the closed state of the preceding two compact material of first extruding;

Fig. 6 is the shape of first extruding back two compact material;

Fig. 7 is for after extruding is finished for the first time, and two compact material upper-lower positions exchange the back closed state;

After Fig. 8 is transposition, the form of blank during through secondary extrusion.

Among the figure: 1, circular die; 2, go up backform; 3, following backform.

The specific embodiment

The present invention is described further below in conjunction with specific embodiment.

The folded material cold precision forging technology of this straight spur gear comprises the steps:

1) at room temperature, the long-pending identical cylinder blank of two blocks is placed circular die 1 along its dead in line, as shown in Figure 5; And carry out two cylinder blank inner face contacts superimposed, push for the first time then, as shown in Figure 6, the starting stage of first crimp, being full of the required stress of corner is the yield stress that blank enters the surrender stage, at this moment near the material circular die 1 of will at first the fitting end face that contacts with each other of blank, it is intact that type is filled at profile of tooth corner place;

2) when two cylinder blanks and circular die 1 binding face during greater than 1/2 blank height, stop extruding, two compact material are taken out;

3) then two compact material upper-lower positions are exchanged, put into circular die 1 again, be superimposed with each other with the blank face that following backform 3 pressure heads contact through last backform 2, as shown in Figure 7, push again; Again the starting stage of crimp, be full of the yield stress that the required stress of corner is a bit larger tham first extruding, the yield stress when pushing less than thin material after the sclerosis.

The present invention is more or less the same when extruding force and first extruding again, and blank also will experience and deformation process like the extrusion type for the first time, and the material at small end face place is easy to outwards bloat, and makes the corner place filling of underfill satisfactory again, as shown in Figure 8.Obtain two qualified parts by twice extruding like this.

The present invention by the technological principle that the two compact material that superpose push the cold precision forging that realizes straight spur gear is: with two onesize blank A, after B is superimposed, see Fig. 1, apply distortion to a certain degree, this moment, deformation process and an independent material of two compact material were that the same (diameter that is this independent material is the same with two compact material, and highly be the twice of every compact material), earlier being cydariform from the middle part outwards bloats, see Fig. 2, just the top of the bottom of a top material and a following material outwards bloats simultaneously, the outer surface that bloats under lower pressure is adjacent to mould, so original when extruding thin material not place's corner of simple filler just be easy to form satisfactory flank profil, take out blank then, two material upper-lower positions being exchanged (or not change place and blank upset), see Fig. 3, put into mould again to exert pressure, the deformation process that the middle part bloats takes place again, make another place's corner of blank also be full of die cavity fully, finish whole forming process, see Fig. 4.The key point of this technology is to utilize folded material extruding to make the corner position of easy deformation least be transformed into the position of easy deformation to finish the flank profil filling smoothly.

The present invention is identical with common extruding on efficient, and maximum pressure then descends about more than 30% than common extrusion process; The part that obtains can reach 8 class precisions.Because not needing heats forged, also needn't fill type fully with what very powerful forcing press can be realized straight spur gear, mould therefor is the ordinary construction mould, simple and reliability height, easy to manufacture and long service life makes this technology have advantages such as simple, reliable, energy-conservation.

Claims

1. the folded material cold precision forging technology of a straight spur gear is characterized in that this technology comprises the steps:

1) the long-pending identical cylinder blank of two blocks is placed circular die (1) along its dead in line, and two cylinder blank inner faces contacts are carried out superimposed, push for the first time then;

2) when two cylinder blanks and circular die (1) binding face during greater than 1/2 blank height, stop extruding, two compact material are taken out;

3) then two compact material upper-lower positions are exchanged, put into circular die (1) again, will in first extrusion process, be superimposed with each other with the blank face that following backform (3) pressure head contacts with last backform (2), push again then;

4) when two compact material and circular die (1) are fully fitted, the profile of tooth filling satisfactory after, stop extruding;

2. the folded material cold precision forging technology of a kind of straight spur gear according to claim 1 is characterized in that, described first extruding, and in the starting stage of its distortion, being full of the required stress of corner is the yield stress that blank enters the surrender stage.

3. the folded material cold precision forging technology of a kind of straight spur gear according to claim 1, it is characterized in that described extruding again is in the starting stage of its distortion, be full of the required stress of corner greater than the yield stress of first extruding, the yield stress when pushing less than thin material after the sclerosis.