JPH01254344A - Extruding equipment for gear - Google Patents

Abstract

PURPOSE:To work a gear free from a underfill, exact in tooth profile and high in accuracy by forming an extruding introduction part where its tooth depth becomes gradually larger toward the extruding direction on the end part of the stock introduction side of a tooth profile forming part having a complete tooth depth. CONSTITUTION:The internal tooth 11 of a die 2 is formed by a tooth profile forming part 11a having a length L1 and a complete tooth depth corresponding to the various dimensions of a gear to be worked and the extruding introduction part 11b having a length l1 smaller than L1 is formed continuously on the end part in the direction of a tooth trace of the tooth profile forming part 11a, in other words, on the end part of the stock introduction side. The extruding introduction part 11b is formed obliquely by a prescribed angle to an axial line in the extruding direction of the die 2 and established so that the tooth depth becomes gradually larger toward the extruding direction. A copy shaping part 11c having nearly the same shape as the end (b) of the extruding introduction part 11 is formed on the end part of an opposite side of the extruding introduction part 11b in the tooth profile forming part 11a. In this way, it is possible to work a gear free from an underfill, exact in tooth profile and high in accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gear cold extrusion processing apparatus, and more particularly to an improvement in a die having internal teeth.

BACKGROUND ART As a conventional method for extruding gears such as helical gears, for example, the method disclosed in Japanese Patent Publication No. 62-2886 is known. This processing method is based on pushing a hollow cylindrical material into a die with internal teeth, and is characterized by the fact that the material pushed in first is substantially pushed by the material pushed in later. It is said that

That is, the left half of FIG. 4 shows the state before the uppermost material Wl is pushed in, and the right half of the figure shows the state after the material Wl is pushed, which is the stage before the material W1 is pushed. Here, the processing of the material W3 in the bottom row is almost completed, and the processing of the material W2 in the middle row has progressed to about half. From this state, as shown in the right half of the figure, when the punch 3 pushes the material wl into the die 2, which has internal teeth l, the material W3, which has been almost completely processed, is pushed by the material W2 and moves into the die 2. The material W2 is pushed out from the lower end, and the processing of the material W2 is almost completed at that point.

Furthermore, the material w1. w2. A mandrel 4 concentric with the punch 3 is inserted into w3 to restrict movement of the material in the radial direction. 5 is a die case, and 6 is a support plate.

Problems to be Solved by the Invention In the above processing method, as shown in an enlarged view in FIG. In contrast to a, the length of the so-called incomplete tooth depth portion 1b, where the tooth depth is smaller than the normal tooth depth, is significantly larger, and therefore, depending on the specifications of the gear, it may not be possible to form perfect teeth. be.

Although this is due to the length ρ of the full tooth depth portion 1a, the cause is that after the material passes through the full tooth depth portion 1a, it undergoes a so-called relief behavior at the incomplete tooth depth portion 1b, resulting in This is thought to be due to the lack of average punch pressure near the die population.

An object of the present invention is to provide a die structure that prevents the above-described defective tooth profile formation.

Means for Solving the Problems For this purpose, in the present invention, the internal tooth shape of the die is formed at the end in the direction of the tooth thread on the material introduction side, inclined at a predetermined angle with respect to the axis of the die, and in the extrusion direction. The structure includes an extrusion introduction part in which only the teeth gradually become higher, and a tooth forming part continuous to the extrusion introduction part and having only complete teeth corresponding to the specifications of the gear.

The above-mentioned inclination angle of the extrusion introduction part and the length of the tooth forming part in the tooth trace direction vary depending on the specifications of the gear to be machined, but their values are determined by the average punch pressure at the gou inlet being a predetermined value. The value is set to the above value.

Function: This structure eliminates unstable movement of the raw material during the extrusion process because there is no incomplete tooth depth as in the conventional case, and defective tooth profile formation is prevented.

Embodiment FIGS. 1 and 2 are diagrams showing an embodiment of the present invention, in which the shape of the internal teeth 11 of the die 2 is different from the conventional one. That is, the internal teeth 11 of the die 2 are formed with a tooth forming part 11a having a length Ll and having a complete tooth depth corresponding to the specifications of the gear to be machined. An extrusion introduction part 11b having a length σl smaller than Ll is continuously formed at the end on the side where the material is introduced. This extrusion introduction part 11b is formed to be inclined by a predetermined angle α with respect to the extrusion direction axis of the die 2, and is set so that only the teeth become gradually higher in the extrusion direction.

Furthermore, at the end of the tooth forming section 11a on the opposite side from the extrusion introduction section 11b, a leveling section 11C having a shape substantially similar to that of the extrusion introduction section 11b is formed.

Here, the values of Ll and α mentioned above naturally vary depending on the specifications of the gear to be machined, and the average punch pressure at the die entrance also changes depending on the values of Ll and α. The quality of the tooth profile accuracy is determined. Therefore, when selecting the values of Ll and α, they are set to values that do not fall below the control limit (lower limit value) of the die population average punch pressure.

As shown in Figures 1 and 3, the Gui population average punch pressure is calculated using the diameter of the punch 3 as D1 and the diameter of the mandrel 4 as d.
Then, F, F,, F,, F.

If the force is defined as below, it can be obtained from equation (1).

F: Maximum extrusion force (=F, +F, +F,) Fl: Frictional force between the unformed material and the straight part in front of the extrusion introduction section F,: Necessary for the material to plastically deform at the extrusion introduction section of the die Force F3: Frictional force between the tooth forming part of the die and the material According to this embodiment, there is no incomplete tooth depth part as in the conventional case, and the material is restrained by the tooth forming part 11a, which is a relatively long complete tooth depth part. Therefore, the material does not escape during the extrusion process, and a highly accurate tooth profile without defects such as underfill can be formed.

Effects of the Invention As described above, according to the present invention, by forming an extrusion introduction part in which only the teeth become gradually higher in the extrusion direction at the end on the material introduction side of the tooth forming part having a complete tooth depth, It is possible to machine high-precision gears without missing parts or defective tooth profiles.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the extrusion processing apparatus of the present invention, FIG. 2 is an enlarged view of the main part of the die shown in FIG. 1, FIG. 3 is a characteristic diagram showing the relationship between extrusion load and extrusion stroke, and FIG. FIG. 4 is a sectional view showing a conventional gear extrusion method, and FIG. 5 is an enlarged view of the main part of FIG. 4. 2...Die, 3...Punch, 4...Mandrel,
11...Internal tooth, lla...Tooth mold molding part, llb...
- Extrusion introduction part, wl, w2. w3...Material. 1C Fig. 3 Stroke -1 Fig. 4

Claims (1)

[Claims] (1) In a device that extrudes a gear by pushing a hollow cylindrical material into a die having internal teeth while regulating the flow of the material in the radial direction, the internal teeth of the die are on the material introduction side. An extrusion introduction part is formed at the end in the tooth thread direction and is inclined at a predetermined angle with respect to the axis of the die, and the tooth height gradually increases toward the extrusion direction.The extrusion introduction part is continuous with this extrusion introduction part and corresponds to the specifications of the gear. 1. A gear extrusion processing device comprising a tooth forming section having a complete tooth depth.