CN1317088C

CN1317088C - Precision forming method for spur gear

Info

Publication number: CN1317088C
Application number: CNB03138823XA
Authority: CN
Inventors: 杨永顺; 陈拂晓; 郭俊卿; 杨茜; 王颜琦
Original assignee: Luoyang Best Technology Co Ltd; Henan University of Science and Technology
Current assignee: Luoyang Best Technology Co Ltd; Henan University of Science and Technology
Priority date: 2003-07-10
Filing date: 2003-07-10
Publication date: 2007-05-23
Anticipated expiration: 2023-07-10
Also published as: CN1569351A

Abstract

The present invention belongs to a forming technology for a gear and provides a precision forming method for a spur gear, which adopts a penetrating type direct extrusion forming method and adopts the way that a pressing head (1) is pressed down from the upper part to cause a bar stock blank (2) heated to a certain temperature to be extruded from the lower part after being extruded through the female mold (4). A forward extrusion forming technology is adopted, the tooth shape of a formed piece is determined by the tooth shape of the female mold, and the forming is comparatively easy. Besides, the limit by the module of a gear is small, the deformation degree of the blank is smaller than the deformation degree of the upsetting and extrusion, and the spherical tensor of stress is far smaller than the spherical tensor of the stress of the closed extrusion state in the process of upsetting and extruding. When the warm extrusion is carried out, the plasticity of a deformed metal is improved, and the resistance is reduced obviously. The deformation resistance for the mold is reduced obviously, the main action is generated at a material holding cavity of the mold, the stress concentration phenomenon is small, and therefore, the service life of the mold is extended.

Description

Spur gear precision forming methods

Affiliated technical field

The invention belongs to forming technology for gear, what relate generally to is a kind of Spur gear precision forming methods.

Background technology

At present, the ripe manufacturing process of straight spur gear is traditional cutting technology, promptly adopts bar blank (selecting rough forging when diameter is big for use), and multiple working procedures such as garden, gear hobbing, shaving and heat treatment are shaped inside and outside face work, boring, car.This method difficulty of processing is big, and production efficiency is low, and the waste raw material are affected the benefit of enterprise, and because be cut off at the fiber that adds the parts of tooth in man-hour, make the intensity of gear not high, influence its bearing capacity.For the large module gear under the heavy duty, its contradiction is more outstanding.

Adopting plastic forming technology to produce gear member, have material-saving, energy-conservation, significant advantages such as processing cost is low, efficient height, and can increase substantially product inherent quality and presentation quality, is one of main method of following Gear Processing.At present, the precision plastic forming process of spur gear is to adopt the upsetting squeeze method basically.Its operation principle is that diameter is directly put into the shaping die less than the short cylindrical blank 2 of root circle as shown in Figure 1, makes pressure head 1 descending then, forces blank to produce plasticity and flows, and promptly forms profile of tooth after being full of die cavity.Because metal blank is being subjected to great restriction near end of a period stage mobile, the distortion of materials drag sharply rises, and adds the rubbing action of gear tooth slot part, makes gear corner filling difficulty, finally causes the profile of tooth part to fill the material defect of insufficient.For this reason, done multinomial research both at home and abroad and remedied, but all be difficult for tooth cavity is full of fully, all the more so when module is big especially; On the other hand, die bore very big stress when this method was shaped, and it is more that descended to die life, and manufacturing cost increases.So the straight spur gear essence is forged and is not entered the industrial applications stage as yet.

Summary of the invention

Purpose of the present invention promptly is to propose a kind of Spur gear precision forming methods, and its forming technology simplification, processing cost reduction, part performance are further improved.

The manufacturing process that the present invention proposes is: adopt through forward extrusion manufacturing process, the mode that adopts pressure head to press down from top makes the bar blank that is heated to uniform temperature be extruded by die and then extrudes from the below.

The length of bar blank is corresponding with the thickness of a gear.

The length of bar blank is corresponding with the thickness that cogs with 2/2, and the back that is shaped cuts off according to needed gear gauge, carries out secondary process again and obtains the gear finished product.

The straight spur gear manufacturing process that the present invention proposes has the following advantages:

1, shaping is easier to.Adopt the forward extrusion forming technology, the profile of tooth of product is decided by the castellated shape of die, is shaped than being easier to, and is subjected to the restriction of module size less.

2, resistance of deformation is little.When adopting forward extrusion, the deformation extent of blank is little than upsetting squeeze, and the sealing squeezed state of spherical tensor of stress during much smaller than upsetting squeeze; When warm extrusion was pressed, the plasticity of deformable metal improved greatly, and drag significantly descends.

3, die life height.The resistance of deformation that mould bore obviously reduces, and mainly acts on the material-holding chamber part of mould, and the stress concentration phenomenon is little, thereby has improved die life.

4, the characteristics that have high-quality and efficient material-saving.Compare with machining, production efficiency and stock utilization all are significantly increased, and tooth accuracy can satisfy the requirement of accurate blank, carry out finishing procedure again one time, can reach the precision of finished product gear.

Description of drawings

Accompanying drawing 1 is existing straight spur gear building mortion schematic diagram.

Accompanying drawing 2 is straight spur gear building mortion schematic diagram of the present invention.

Accompanying drawing 3 is the A-A profile of Fig. 2.

Among the figure, 1, pressure head, 2, blank, 3, extruded sleeve, 4, die, 5, cushion block, 6, push rod.

The specific embodiment

In conjunction with the accompanying drawings 2, accompanying drawing 3, the embodiment of the invention is illustrated:

The present invention adopts through forward extrusion manufacturing process, and 1, bar blank 2 is coated with is coated with lubricant after being heated to uniform temperature or being heated to uniform temperature behind the lubricant; Forming temperature changes to some extent according to the difference of extrusion blank material, generally at 650 ℃～850 ℃; The heating-up temperature of bar blank 2 will be higher than forming temperature, and its temperature difference is delivered to the temperature drop-out value of building mortion from heating for the heating back; As to adopt diameter be the 20CrMnTi bar blank of 70mm, under 700 ℃ of temperature, push, and when deformation extent is 70%, the about 1200MPa of its extrusion pressure; 2, heated blank is put into extruded sleeve 3, the pressure head 1 descending blank that forces is extruded the back from the outflow of die below by die 4; Extruded sleeve 3 also can be structure as a whole with die 4, and be referred to as die with extruded sleeve and die this moment; The cross section of pressure head 1 working portion is circular; 3, put into isolation lubricant repetitive process 2 in the extruded sleeve 3, it is up to be about to pressure head 1, injects in extruded sleeve 3 and isolates lubricant, and the bar blank of another section heating is put into extruded sleeve 3, and pressure head is descending, continues to press down; 4, when one section complete extrusion went downwards to certain position, with its taking-up, shaping was finished; The length of bar blank 2 can be corresponding with the thickness of a gear, also can be corresponding with the gear thickness more than 2 or 2, cut off according to the length dimension of each gear, and carry out secondary process again and become the gear finished product.

Claims

1, a kind of Spur gear precision forming methods, it is characterized in that: adopt through forward extrusion manufacturing process, the mode that adopts pressure head (1) to press down from top makes the bar blank (2) that is heated to 650～850 ℃ be extruded by die (4) and then extrudes from the below.

2, Spur gear precision forming methods according to claim 1 is characterized in that: the length of bar blank (2) is corresponding with the thickness of a gear.

3, Spur gear precision forming methods according to claim 1, it is characterized in that: the length of bar blank (2) is corresponding with the thickness that cogs with 2/2, cut off according to needed gear gauge after being shaped, carry out secondary process again and obtain the gear finished product.