JPS6067023A - Rough machining of variable rack - Google Patents

Abstract

PURPOSE:To minimize deformation in finish machining and eliminate cutting of flow of work material by dividing teeth formed on a rack into an appropriate number of sections every approximate torsional angle and by making rough machining according to each average torsional angle of every section. CONSTITUTION:A body 5 is secured to a base 4 slid by a guide 3 and a holder 7 having a clamp 6 is provided on the body 5. And a material to be machined 11 is retained in the clamp 6 and opposed to the edge 8 of a broaching machine. To obtain a roughly machined work 1 having a center portion A with a large torsional angle theta1 and both end portions B, C with small torsional angle theta2, the clamp 6 retaining the material to be machined 11 is inclined to theta1 and the A portion is machined with the broach 8a of a first broaching machine, and inclined to theta2 and B and C portions are machined with the broach 8b of a second broaching machine arranged in parallel. After this rough machining, finish machining is made with a finish die. Then machining deformation is less and flow of work is not cut. If the number of sections is increased, a tooth shape closer to the complete product can be naturally obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of rough machining performed before finishing and finishing when machining a barrier pull rack.

The barrier pull rack described in item 1 is a rack/rack that is used in steering mechanisms of automobiles, etc., and is made by meshing a rack provided on the tie rod side with a pinion provided on the steering wheel shaft side.
It is used for the rack of the rudder claw device 6 in the and-pinion format, and is
? , I and L are each made of lead.//I have a rack with a differential fit or f disorder.

This type of steering mechanism for barrier pull racks was developed to improve the steering operability of front-wheel drive passenger cars, which have been increasingly adopted in recent years. By reducing the pressure angle of the teeth toward both ends of the tooth profile at the center and gradually narrowing the pitch,
The amount of movement of the rack is reduced relative to the rotation of the pinion at the end. Therefore, engagement at the center of the rack requires a steering force that does not impair straight-line stability, and engagement at the ends of the rack, that is, as the handle is cut in, the steering force is reduced.
This makes it possible to improve steering operability even in front-wheel-drive passenger cars that place a greater load on the front wheels.

In addition, the rack and pinion has a helical gear shape in order to increase its I meshing ratio, and the rack and pinion have a helical angle, but as mentioned earlier,
Since the rack is meshed with a pinion and a rack whose pressure angle and pitch are changed respectively, the tooth profile of the central part of the rack that meshes with the tooth tip of the pinion, and the tooth profile of both ends of the rack that meshes with the tooth root of the pinion. The torsion angle gradually decreases toward .

In the past, processing of such racks was carried out in Japanese Unexamined Patent Application Publication No. 1986-
There is something like the one shown in No. 48540. Prior to finishing, a broaching machine is used to roughly machine a plurality of rack teeth that are inclined in a certain direction on the rack material, and then a finishing die is used to perform cold working to form the final shape.

However, in such a rack processing method, the twist angles of the teeth at both ends and the middle part of the rack are different, so the machining deformation of the root part becomes large during cold working, so the flow of the workpiece is affected. The problem was that the rack teeth were cut midway, resulting in a decrease in the strength of the rack teeth.

This invention was made in view of the above-mentioned problems, and aims to provide a barrier pull rack with high strength.

There is.

The rough machining method for a barrier pull rack according to the present invention is characterized in that the teeth to be formed on the rack are divided into an appropriate number of approximate torsion colors, and rough cutting is performed for each of the average torsion colors of each of the divisions. It is said that

The present invention will be explained below based on the drawings.

1 to 7 are diagrams illustrating an embodiment of the rough machining method for a barrier pull rack according to the present invention.

That is, barrier pull rank 1 shown in figure f51 indicates a state in which rough cutting has been completed on the round bar-shaped workpiece 11, and the center part A has a large twist angle θ. , and both end portions B and C having a small twist angle θ2, and are formed according to the twist angles in the two directions.

The central portion A and both end portions B and C are divided into approximate torsion angles (+j) of the teeth of the entire barrier pull rank 1, and each of the divided portions A, B, and C (+1 average torsion angle Rough νj processing is performed corresponding to θH, 07, 02.

As mentioned above, the barrier pull rack 1 as a product has a pressure angle that gradually increases from the center tooth toward both ends, a pitch that becomes narrower, and a torsion angle that becomes smaller. It is assumed that each part of a certain tooth profile is similar, and the average twist angle θ2 at both ends B and C is the same value.

FIGS. 2 to 4 are diagrams illustrating a broaching machine 2 that performs rough cutting when processing the helia pull rack 1. FIG.

That is, the configuration of this broaching machine 2 is such that the broaching tool main body 5 of the workpiece 11 is fixed to the substrate 4 which slides on the guide part 5 and is guided, and the broaching tool main body 5 is fixed to the broaching tool main body 5. The holder part 7 having the clamp 6 is a counterfeit, and a first broach blade 8a is provided opposite to the processing portion of the workpiece 11 held by the clamp 6.

The first broach blade 8a is held in a broach holder 10 that can be accessed by a first ram 2a that moves up and down. Further, a second ram 2b is provided in parallel to the first ram 2a, and a second broach blade 8b is also held by a broach holder 10 in the second ram 2a.

As shown by the imaginary line in FIG. 4, the tool main body 5 is arranged so that the processing portion of the workpiece 11 can face both the +iii-th broach blade 8a and the second broach blade 8b. It is guided to the kite section 3 and can be moved.

Further, the holder portion 7 is rotatable in a direction (arrow in FIG. 2) in which the cutting angle of the broach blades 8a, 8b is variable with respect to the processing portion of the workpiece 11, and
As shown in FIG. 3, fitting parts 12a to 1 corresponding to each angle
2e is provided, and after rotating the holder part 7 until the required cutting angle is reached, the positioning pin 13 provided on the side of the tool body 5 is inserted into the corresponding fitting part 12a~ It is fixed by fitting into 12e.

To perform rough cutting using the broaching machine 2 configured as described above, first, as shown in FIG.
After holding the workpiece 11 at
(See figure t51), and then fixed using the positioning tool 12. Then, by lowering the first ram 2a in this state, the first broach blade 8a
Then, the center portion A of the workpiece 11 is cut.

Next, the positioning tool 12 is released and as shown in FIG.
The holder part 7 is rotated again to match the cutting angle to the average torsion angle θ2 of both ends B and C (see 11th Δ), and then fixed by the positioning tool 12 as well, and the machining part of the workpiece 11 is Move the main body 5 until it is in a position facing the second broach blade 8b. Then, by lowering the second ram 2b in this state, both ends B and C are formed on the workpiece 11 with the second broach blade 8b.

In addition, at this time, the first broach blade 8a has a blade width and the number of blades that can form the center part A, and the second broach blade 8b' has a part corresponding to the center part A, and It has a blade width and number of blades that can form both ends B and C.

The center part A and both end parts B are formed through the above steps.

As shown in FIG. 1, the workpiece 11 on which C is formed is
Rough machining of Barrier Pull Rack 1 completed! , a ridge.

And after this rough processing, the finishing die! Finishing is performed by η to form a tooth profile with each pressure angle, torsion angle, and pinch.The deviation is reduced in processing deformation and can be processed without cutting the flow of the workpiece material at the base of the rack tooth. .

In the above embodiment, the teeth of barrier pull rank 1 are divided into three parts: the central part A and both end parts B and C, but this division is limited to three parts. Without l-ha,
By increasing the number of sections, the tooth profile at the time of rough machining can be brought closer to the tooth profile of the finished product.

In addition, although the broaching machine 2 has been explained as an example of a cutting device that performs rough cutting, there are also cutters for cutting the central portion A and for cutting both ends B and C, as shown in FIGS. 8 and 9. 21. Using a general cutter device 20 equipped with 22,
For each cutting process by each cutter 21, 22, the twist angle θ1.

The rough machining method according to the present invention can be applied even if the mounting angle of the workpiece 11 is changed according to the method of the present invention.

As described above, according to the present invention, when processing a barrier pull rack, as a rough processing method, the teeth to be formed on the rack are divided into an appropriate number of approximate torsion angles of 4η,
Since the rough cutting is performed in accordance with the average twist color of each section, it is possible to process the barrier pull rack without reducing the strength of the rank teeth.

[Brief explanation of drawings]

Figure 1 is a plan view showing a barrier pull rack formed by the rough machining method according to the present invention, Figure 2 is a side view illustrating a broaching machine that performs rough slicing, and Figure 3 is a holder section of the broaching machine. Fixed position guide 5h shop ri b ff
M ITII-J-@Tr: 1iS'l c*
AI+! 711-) A plan view of the broaching machine, and FIGS. 5 to 7 are sequential explanations of the state in which the average torsion angle (ij) is applied to the workpiece that has been reached into the holder part. A front view, FIG. 8, and FIG. 9 are a front view and a side view showing a general cutter device to which the rough machining method according to the present invention can be applied. 1... Barrier pull rack, θ1.02... Torsion Corner, A...Central part (section), B, C...Both ends (section). Patent applicant: Nissan Motor Co., Ltd. Representative Patent Attorney Yutaka Oshio Ice 12 (j Tomoe Figure 4 Figure 5 Figure 6B 1 Figure 7

Claims (1)

[Claims] (1) When plastic-finishing a rack with tooth profiles with different helix angles after rough machining, the teeth to be formed on the rack are divided into an appropriate number of torsion colors that approximate each other, and the average torsion color of each of the above divisions is dealt with. A method for rough machining of a barrier pull rack, characterized by performing the following steps: