CN112958716B

CN112958716B - Gear forming method

Info

Publication number: CN112958716B
Application number: CN202110126150.7A
Authority: CN
Inventors: 龚峰; 闫超; 罗和喜
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2022-03-18
Anticipated expiration: 2041-01-29
Also published as: CN112958716A

Abstract

The invention belongs to the technical field of plastic micro-forming of gears, and particularly relates to a gear forming method. The gear forming method comprises the following steps: preparing a die, namely processing male dies on a first die plate, processing female dies on a second die plate, wherein the female dies are provided with die pressing cavities for arranging blanks; and heating and forming, namely driving the male dies which are arranged in a sliding manner to move towards the blank by the force application mechanism so as to enable two ends of the blank to be respectively abutted against the two male dies, heating the blank to a preset temperature by the heating device, and driving the corresponding male dies to move by the force application mechanism to form the blank by die pressing. The invention forms a blank by die pressing through the force application mechanism, and further obtains the needed micro gear.

Description

Gear forming method

Technical Field

The invention belongs to the technical field of plastic micro-forming of gears, and particularly relates to a gear forming method.

Background

Currently, miniaturization of products, which enables unique product functions to be realized in microscale geometries and features, and further reduces the weight and volume of products, is an emerging trend that facilitates product usage. The volume micro-forming technology is widely applied and developed due to the advantages of large batch, high efficiency, good mechanical property and the like. As a novel processing technology, the volume micro-forming shows huge potential in various aspects such as processing efficiency, processing performance and the like, and can meet the increasing demand of micro parts.

To facilitate large-scale machining and reduce costs, many of the micro-gears are machined from polymeric materials. Metal gears are more advantageous than polymeric gears in several ways: firstly, the thermal expansion coefficient is small, the thermal stability is better, and the method can be used in the environment with large temperature change; secondly, the metal gear has high hardness and strength, good wear resistance, good deformation resistance and high temperature performance, and can adapt to various complex environments; thirdly, the repeatability of the processing precision is higher.

The traditional micro-gear processing method has the advantages of organic processing and powder metallurgy, but the processing procedure is complex, the time consumption is long, the environment is not protected, the mechanical property of parts is poor, the precision is difficult to guarantee, and the cost is high.

Disclosure of Invention

An object of the embodiments of the present application is to provide a gear forming method, which aims to solve the problem of how to micro-machine a metal blank to form a gear.

In order to achieve the purpose, the technical scheme adopted by the application is as follows: there is provided a gear forming method for preparing a blank into a gear, the gear forming method comprising the steps of:

preparing a die, namely processing a male die on a first die plate, processing a female die on a second die plate, wherein the female die is provided with a die pressing cavity for arranging the blank, the male die is provided with a first gear tooth array structure, the cavity wall of the die pressing cavity is provided with a second gear tooth array structure, the first gear tooth array structure is matched with the second gear tooth array structure, the male dies are provided with two male dies, one male die is positioned at one side of the female die, one end of the male die is positioned in the die pressing cavity, the other male die is positioned at the other side of the female die, one end of the male die is arranged in a sliding mode relative to the die pressing cavity, and the blank is positioned between the two male dies;

and heating and forming, namely driving the male dies which are arranged in a sliding manner to move towards the blank by virtue of a force application mechanism so as to enable two ends of the blank to be respectively abutted against the two male dies, heating the blank to a preset temperature by virtue of a heating device, and driving the corresponding male dies to move by virtue of the force application mechanism and carrying out die pressing and forming on the blank so as to copy the second gear tooth array structure to the blank.

In one embodiment, the mold preparation comprises the steps of:

s11: processing the first gear tooth array structure on the first template through wire cutting so as to divide the first template into a plate body and a male die, wherein the first gear tooth array structure comprises a plurality of first tooth heads which are arranged at intervals, and at least one first tooth head is connected with the plate body;

s12: detachably connecting the first tooth head separated from the plate body to the plate body by a fixing wire;

s13: separating each of the first bits connected to the plate body in the step S11 by wire cutting.

In one embodiment, in the S12 step, the fixing wires are glued between the corresponding first tooth heads and the plate body by glue to detachably fix the first tooth heads and the plate body.

In one embodiment, in the S11 step, the first tooth head separated from the plate body is subjected to the wire cutting repeatedly.

In one embodiment, in the step S11, each of the first tooth heads connected to the plate body is disposed adjacent to each other.

In one embodiment, the die pressing cavity is machined on the second template through an electric discharge machining process, and the second gear tooth array structure is machined through wire cutting, and the second gear tooth array structure comprises a plurality of second gear heads which are arranged at intervals.

In one embodiment, the heating device comprises a pulse power supply, two electrodes of the pulse power supply are respectively and electrically connected with the two male dies, the two male dies and the blank form a loop, and the male dies are coated with high-impedance layers.

In one embodiment, the high-resistance layer is an alumina-resistance layer.

In one embodiment, the punch is disposed convexly against the end face of the blank.

In one embodiment, the female die is floated a predetermined distance in a force applying direction away from the force applying mechanism to fill the die pressing cavity with the blank.

The beneficial effect of this application lies in: the method comprises the steps of preparing a female die and a male die, arranging a blank in a die pressing cavity, heating the blank to a preset temperature, and forming the blank through die pressing by a force application mechanism, so that the second gear tooth array structure is copied to the blank, and a required micro gear is obtained.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a schematic structural diagram of a male die provided in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a female mold provided in an embodiment of the present application;

fig. 3 is a flow chart of a method of the present application.

Wherein, in the figures, the respective reference numerals:

10. a first template; 11. a male die; 12. a plate body; 13. a first tooth head; 30. a first gear tooth array structure; 14. fixing the wire; 131. a first tooth head; 1312. the twelfth first tooth head; 151. a feed point; 152. retracting a cutter point; 20. a second template; 23. a female die; 22. a second tooth head; 24. a second gear tooth array structure;

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Referring to fig. 1 and fig. 2, a gear forming method for manufacturing a gear from a blank is provided in an embodiment of the present application, where the blank is a metal blank, and optionally, T red copper in this embodiment. The T2 red copper has good plastic forming ability, excellent electric conductivity, heat conductivity, corrosion resistance and processing performance, and is more and more widely applied to the fields of micro electro mechanical systems and the like. The formed gear is a gear with a tiny size, the modulus of the gear is 0.1-0.4 mm, and the number of teeth is 12 or 24.

The gear forming method comprises the following steps:

s1: preparing a die, namely processing a male die 11 on a first die plate 10 and processing a female die 23 on a second die plate 20, wherein the first die plate 10 is made of YG8 hard alloy and the second die plate 20 is made of D2 quenched steel. The female die 23 is provided with a die pressing cavity for blank arrangement, the male die 11 is provided with a first gear tooth array structure 30, a second gear tooth array structure 24 is machined on the cavity wall of the die pressing cavity, the first gear tooth array structure 30 is matched with the second gear tooth array structure 24, the male die 11 is provided with two male dies, one male die 11 is located on one side of the female die 23, one end of the male die is located in the die pressing cavity, the other male die 11 is located on the other side of the female die 23, one end of the other male die is arranged in a sliding mode relative to the die pressing cavity, and the blank is located between the two male dies 11. Alternatively, the female die 23 is laid flat, one male die 11 is located below the female die 23, the other male die 11 is located above the female die 23, the male die 11 located below the female die 23 is fixedly arranged, and the male die 11 located above the female die 23 is arranged in a sliding manner up and down.

S2: and (4) heating and forming, namely driving the male dies 11 arranged in a sliding manner to move towards the blank by a force application mechanism so that two ends of the blank are respectively abutted against the two male dies 11, and heating the blank to a preset temperature by a heating device, wherein optionally the heating temperature range of the blank is 250-500 ℃. The force applying mechanism drives the corresponding male die 11 to move and die-form the blank so as to copy the second gear tooth array structure 24 to the blank. The force application mechanism in the embodiment is a one-way compression device, the maximum forming force of the force application mechanism reaches 50kN, the precision is I level, and the displacement resolution is 8 mu m.

The blank is arranged in the die pressing cavity by preparing the female die 23 and the male die 11, and then the blank is heated to a preset temperature and is formed by die pressing through the force application mechanism, so that the second gear tooth array structure 24 is copied to the blank, and the required micro gear is obtained.

In one embodiment, the mold preparation comprises the steps of:

s11: machining a first gear tooth array structure 30 on a first template 10 through wire cutting to divide the first template 10 into a plate body 12 and a male die 11, wherein the first gear tooth array structure 30 comprises a plurality of first gear teeth 13 arranged at intervals, and at least one first gear tooth 13 is connected with the plate body 12; optionally, a feed point 151 and a retract point 152 are set on the first die plate 10 according to the number of the first teeth 13 to be machined, and in this embodiment, the feed point 151 and the retract point 152 are located at the same position. The number of the first tooth heads 13 in this embodiment is twelve and numbered in sequence. Referring to fig. 1, half teeth are retained in each of the first tooth head 131 and the twelfth tooth head 1312 while being connected to the plate body 12, and the other first tooth heads 13 are wire-cut and completely separated from the plate body 12. Because the first tooth head 13 and the twelfth tooth head which are positioned at the head and the tail are both kept connected with the plate body 12, the gravity moment generated in the machining process of the male die 11 is avoided, so that the male die 11 is deviated, and the machining precision of the male die 11 is influenced.

S12: the first bit 13 separated from the plate body 12 is detachably connected to the plate body 12 by a fixing wire 14; optionally, the second to eleventh first tooth heads 13 to 13 are connected to the plate body 12 through the fixing wires 14, and in the threading and fixing processes of the second to eleventh first tooth heads 13 to 13, the fixing wires 14 are alternately arranged at the tooth tops of the corresponding first tooth heads 13 and the tooth roots of the corresponding first tooth heads 13, so that not only can the fixing force be uniformly distributed, but also the threading and fixing efficiency can be improved, and finally, the generation of the gravity moment in the processing process of the male die 11 is avoided, so that the male die 11 is deviated, and the processing accuracy of the male die 11 is affected. Alternatively, the fixing wire 14 may be a wire electrode in wire cutting.

S13: each of the first bits 13 connected to the plate body 12 in the step of separating S11 by wire cutting. Optionally, the first No. first tooth head 131 and the twelfth No. first tooth head 1312 are subjected to wire cutting by a wire cutting process, so that complete separation of the punch 11 from the plate body 12 is achieved.

Alternatively, when the punch 11 is machined by linear cutting, the first tooth head 13 at the tool retracting point 152 has a defect of incomplete tooth profile, and secondary machining is generally required to eliminate the defect, but the workbench needs to be replaced in the secondary machining process, and the replacement of the workbench causes machining errors, which is not favorable for controlling the machining precision. By means of the wire-threading fixing method, secondary machining can be performed on the male die 11 under the condition that the workbench is not replaced, the defect that the tooth profile of the corresponding first tooth head 13 is incomplete is effectively overcome, and machining errors caused by replacement of the workbench are avoided.

In one embodiment, in the S12 step, the fixing wire 14 is glued between the corresponding first tooth head 13 and the plate body 12 by glue to detachably fix the first tooth head 13 and the plate body 12. Optionally, the wire electrode as a fixing and conducting medium sequentially penetrates into the machining gap between the first tooth head 13 and the plate body 12, and the wire electrode and the plate body 12 are locally fixed by glue, so that a wire breakage phenomenon in a slow-moving wire machining process caused by glue overflow is avoided during glue dripping, and in order to further avoid the situation, the wire electrode penetrates into positions close to the first tooth head 131 and the twelfth tooth head 1312 to isolate glue circulation.

In one embodiment, in the step S11, the wire cutting is repeated a plurality of times for the first bit 13 separated from the plate body 12. Optionally, the second to eleventh first tooth heads 13 to 13 are subjected to 9 times of trimming to improve the dimensional accuracy of each first tooth head 13 and reduce the surface roughness.

In one embodiment, in the S11 step, each first tooth head 13 connected to the plate body 12 is disposed adjacent to improve the connecting force of the punch 11 to the plate body 12.

In one embodiment, the die cavity is machined in the second die plate 20 by an electric discharge machining process, and the second gear tooth array structure 24 is machined by wire cutting, wherein the second gear tooth array structure 24 comprises a plurality of second teeth heads 22 arranged at intervals, and the first teeth heads 13 and the second teeth heads 22 are matched.

In one embodiment, the heating device comprises a pulse power supply, two electrodes of the pulse power supply are respectively and electrically connected with the two male dies 11, the two male dies 11 and the blank form a loop, and the male dies 11 are coated with high-impedance layers. The high resistance layer increases the heat productivity of the male die 11, and the heat is transferred to the blank by heat conduction, thereby improving the processing plasticity of the blank. It can be understood that the blank is subjected to die pressing forming by the aid of a pulse power supply, and current is introduced into the blank, so that an electro-plastic effect is generated in the blank, namely, a composite effect is formed by four physical effects, namely a joule heat effect, a magnetic field compression effect, a skin effect and a pure electro-plastic effect, so that the plasticity of the blank is improved, and the die pressing forming is facilitated. Optionally, the pulse current assisted micro-forming has the characteristics of one-time forging forming, high material utilization rate, high precision controllability, easiness in batch production and the like.

In one embodiment, the high-resistance layer is an alumina resistance layer, and the heat generation efficiency is improved by arranging the high-resistance layer.

In one embodiment, the end surface of the male die 11 abutting the blank is convex, so that the blank can be extruded to the periphery of the die cavity, which is beneficial to increase the transverse die pressure of the blank, so that the blank fills the whole die cavity towards the second gear tooth array structure 24, and the second gear tooth array structure 24 is copied to the blank.

In one embodiment, the female die 23 is floated a predetermined distance in a force application direction away from the force application mechanism to allow the blank to fill the die cavity. After the blank is heated and molded, the female die 23 is driven to float upwards for a preset distance, so that the upward static friction force of the female die 23 on the blank is converted into downward dynamic friction force, namely harmful friction is converted into favorable friction, and the blank which is extruded and deformed can be further filled in dead corners of a die pressing cavity by moving the female die 23, so that the precision of gear forming is improved.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.

Claims

1. A gear forming method for preparing a blank into a gear, comprising the steps of:

heating and forming, namely driving the male dies which are arranged in a sliding manner to move towards the blank by a force application mechanism so as to enable two ends of the blank to be respectively abutted against the two male dies, heating the blank to a preset temperature by a heating device, and driving the corresponding male dies to move by the force application mechanism and press-forming the blank so as to copy the second gear tooth array structure to the blank;

the preparation of the mould comprises the following steps:

s13: separating each of the first tips connected to the plate body in the step S11 by wire cutting to achieve complete separation of the punch from the plate body.

2. The gear forming method according to claim 1, wherein: in the step S12, the fixing wires are glued between the corresponding first tooth heads and the plate body by glue to detachably fix the first tooth heads and the plate body.

3. The gear forming method according to claim 1, wherein: in the step S11, the first tooth head separated from the plate body is subjected to the wire cutting repeatedly a plurality of times.

4. The gear forming method according to claim 1, wherein: in the step S11, the first tooth heads connected to the plate body are disposed adjacent to each other.

5. The gear forming method according to claim 1, wherein: and processing the mould pressing cavity on the second template through an electric spark processing technology, and processing the second gear tooth array structure through wire cutting, wherein the second gear tooth array structure comprises a plurality of second gear heads which are arranged at intervals.

6. The gear forming method according to claim 1, wherein: the heating device comprises a pulse power supply, two electrodes of the pulse power supply are respectively and electrically connected with the two male dies, the two male dies and the blank form a loop, and a high-impedance layer is coated on the male dies.

7. The gear shaping method according to claim 6, wherein: the high-resistance layer is an alumina resistance layer.

8. The gear forming method according to claim 1, wherein: the convex die is abutted to the end face of the blank and is arranged in a convex surface mode.

9. The gear forming method according to claim 1, wherein: the female die floats for a preset distance along the force application direction deviating from the force application mechanism so that the blank is filled in the die pressing cavity.