JPS6358065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a flat die for rolling crown teeth on workpieces such as gears and splines.

Conventional Example Conventionally, the tooth surfaces of teeth such as gears and splines are generally formed into curved surfaces as shown in Figs. 1 and 2 (such teeth are hereinafter referred to as crown teeth). As shown in the figure, the tooth surface 1a is in the tooth trace direction of the tooth 1, which is parallel to the rotation axis of the workpiece.
The tooth has a shape in which the center portion 1b of the tooth bulges out from both ends 1c with respect to O', in other words, both ends 1c of the tooth have a receding shape with respect to the center portion 1b, that is, a crown shape. This bulging amount α is about 10μ.

In this way, by using crown teeth for the teeth of gears, etc., it is possible to absorb errors in the meshing of gears, etc., and it is also possible to prevent the teeth from seizing by sufficiently distributing lubricating oil between the meshing teeth. becomes.

Incidentally, although it is well known that gears and the like can be manufactured by rolling using a flat die, a method of creating crown teeth by this rolling has not been attempted in the past.

When trying to create a crown tooth by rolling with a flat die, it is easy to think of the following:
As shown in FIG. 3, each tooth surface 2a of each tooth 2b of the flat die 2 is made to correspond to a crown tooth 1 of a gear, etc., so that both ends of the tooth surface bulge out from the center. It is to be made as follows. However,
In reality, it is extremely difficult to form each tooth 2b of the flat die 2 into such a shape.

In view of the above-mentioned conventional circumstances, the present inventors have already provided a flat die capable of creating crown teeth on a workpiece. One of them is shown in Japanese Patent Application No. 57-66023, and the other one is shown in Japanese Patent Application No. 57-76795. These flat dies have a finishing tooth group consisting of tapered teeth or twisted teeth, and these teeth are used to generate crown teeth on the workpiece.

4 and 5 schematically show the flat die described above. Figure 4 shows the former set of flat dies. The flat dies 3a and 3b are each composed of a tooth group KU with a tooth, a finishing tooth group SI, and a relief tooth group NI, and the tooth arrangement surface 3e of the finishing tooth group SI of one flat die 3a has one of the teeth of the flat die 3a. A tapered tooth _T1 is provided whose tooth thickness decreases from side S to the other side S'.
On the other hand, the tooth array surface 3f of the finishing tooth group SI of the other flat die 3b is provided with tapered teeth _T2 whose tooth thickness decreases from the other side S' to the one side S. That is, the taper teeth T ₁ and T ₂ have tapers in opposite directions.

On the other hand, a set of flat dies for the latter is shown in FIG. These flat dies 3a, 3b are used for each finishing tooth group.
Twisted teeth T ₁ ′ and T ₂ ′ are provided on the tooth arrangement surfaces 3e and 3f of the SI, and the twisted teeth of one flat die 3a
T ₁ ′ has a tooth helix angle that is slightly larger than the tooth helix angle of the workpiece (in the case of a spur gear, this helix angle is 0°) by an angle β;
The helical tooth T ₂ ′ of b has a tooth helix angle that is slightly smaller than the tooth helix angle of the workpiece by an angle β. In other words, if the workpiece is a spur gear,
The helix angle of the helical tooth T ₁ ′ of the flat die 3a is +β,
The helix angle of the helical teeth T ₂ ' of the flat die 3b is −β.
Furthermore, if the workpiece is a helical gear with a helix angle of +5°, for example, the helical tooth helix angle of the helical tooth T ₁ ' of the flat die 3a is +6°, and the helical tooth of the flat die 3b is a helical gear.
The twist angle of T ₂ ′ is, for example, +4°.

By the way, each pair of flat dies 3a and 3b shown in FIGS. 4 and 5 have different reciprocating patterns on both sides of the workpiece 4, as shown in FIG. 6, similar to the well-known flat dies. The crown teeth are rolled on the circumferential surface of the workpiece 4 by being attached to the positions of the dynamic fulcrums and moving in opposite directions as shown by the arrows in the figure.

However, the above two flat dies are shown in Figure 6.
When used in this manner, there is a problem in that the workpiece shakes or vibrates due to the shape of the tapered teeth or twisted teeth of the finishing tooth group, resulting in poor rolling accuracy. The present inventors investigated the cause and found that it lies in the following points.

That is, first of all, if we talk about the former flat die, that is, the flat die shown in FIG. 4, if we look through the state in which the pair of flat dies 3a and 3b overlap as shown in FIG. ₁ and T ₂ have different directions. i.e. T ₁
The thick end of the thick tooth is located on one side S, and now there is one tapered tooth.
The thick end of T ₂ is located on the other side S'.

By the way, the tapered teeth T ₁ and T ₂ have a larger amount of machining on the tooth 4a of the workpiece 4 at the thicker end than at the opposite end, so as shown in FIG. 9, one of the flat dies 3a , its tapered tooth T ₁
The reaction force against the load L ₁ applied to the thick end of the thick tooth is,
Since the reaction force is greater than the reaction force against the load _L2 applied to the opposite side, the workpiece 4 tries to rotate in the direction of arrow Y. On the other hand, regarding the other flat die 3b, the reaction force against the load L ₁ at the thick end of the tapered tooth T ₂ is larger than the reaction force against the load L ₂ on the opposite side, so the same rotation direction Y as above is applied. Workpiece 4
will be rotated. In this way, the workpiece 4
Since a rotational force, that is, a torsional force is applied to the workpiece 4, runout or vibration occurs during processing.
Therefore, the accuracy of the rolling process becomes extremely poor.

On the other hand, a pair of flat dies 3a, 3 shown in FIG.
b, as shown in Fig. 8, if a pair of flat dies 3a and 3b are superimposed and viewed through, one tapered tooth T ₁ ′ and the other tapered tooth T ₂ ′ are the same. They are twisted in the same direction, that is, their tooth traces match. Therefore, as shown in FIG. 10, one twisted tooth T ₁ ' acts on one tooth 4a of the workpiece 4 as shown,
The workpiece 4 is about to rotate in the direction of the _arrow
Since it acts on a' in the direction shown, the workpiece 4 also tries to rotate in the direction of the arrow X in this case. Therefore, as in the case described with reference to FIG. 9, there is a problem in that run-out or vibration occurs in the workpiece 4 and the rolling accuracy deteriorates.

Tapered teeth T ₁ , T ₂ or twisted teeth as above
As long as T ₁ ′ and T ₂ ′ are used, it is impossible to completely solve the above-mentioned runout or vibration phenomenon because these teeth act on the teeth of the workpiece with different forces in the width direction. It is. However, the inventors of the present invention conducted extensive research in order to resolve these problems, and found that all of the above-mentioned flat dies have a function of imparting a crown shape to the teeth of the workpiece on the tapered teeth or twisted teeth of the finished teeth. In addition, we discovered that a major cause of this problem lies in the ability to reduce the thickness of the tooth itself to a predetermined thickness. That is, as shown in FIG. 11, the tapered teeth T ₁ , T ₂ and the twisted teeth T ₁ ′, T ₂ ′ have a very large thickness D, respectively, with respect to the tooth 4a of the workpiece.
It acts on the tooth 4a to reduce D'.
In this way, as the machining allowances D and D' become larger, the difference between the loads L ₁ and L ₂ of the flat die on the workpiece 4 becomes larger in FIG.
In figure 0, the torsion teeth T ₁ ′, T ₂ ′ of the workpiece tooth 4
The unbalanced load on a increases, and therefore the torsional force on the workpiece 4 also increases.

Purpose of the Invention Therefore, the present invention provides a method for reducing the thickness of the workpiece to a predetermined thickness before rolling the workpiece with a crown-forming tooth such as a tapered tooth or a twisted tooth. By limiting the machining of the teeth of the tooth preparation tooth group to the side corner portions of the teeth of the workpiece, the processing load on the crown tooth preparation tooth group is reduced, that is, the load of the flat dies 3a, 3b on the workpiece 4 is reduced. _L1 , _L2
By making the torsion teeth T ₁ ′ and T 2 ′ smaller, or reducing the unbalanced loads on the workpiece teeth 4a of the torsion teeth T 1 ′ and T ₂ ′, the runout and vibration of the workpiece 4 can be prevented and the machining accuracy of the workpiece can be improved. It is something we try to improve.

Structure, operation, and effects of the present invention In order to achieve the above object, the present invention was configured as follows.

In other words, the finishing tooth group of each flat die is a primary straight tooth whose tooth thickness is constant in the tooth trace direction and which acts on each tooth of the workpiece to uniformly reduce the tooth thickness as a whole. A group of finishing teeth, which are disposed subsequent to the group of primary finishing teeth, act on each side corner of each tooth of the workpiece whose tooth thickness is reduced overall by the group of primary finishing teeth. It is characterized by comprising a secondary finished tooth group consisting of crown tooth preparation teeth that further reduce the tooth thickness at the corner portion.

According to the above configuration, the teeth of the secondary finishing tooth group are used to machine only the corner portions of the side surfaces of the teeth of the workpiece, and do not have an active function of reducing the tooth thickness itself, so there is a processing burden. In other words, the load on the workpiece is reduced, and therefore the workpiece is prevented from wobbling or vibrating, making it possible to perform highly accurate machining.

Embodiments The present invention will be specifically described below with reference to embodiments shown in FIGS. 12 to 15.

FIG. 12 shows a first embodiment, that is, an improved version of the first conventional example shown in FIG. 4, and FIG. 13 shows a second embodiment, which is an improved version of the second conventional example shown in FIG. ing.

First, the first embodiment shown in FIG. 12 will be described.
As shown in the figure, the general configuration of the pair of flat dies 3a, 3b is the same as that of the first conventional example, and is composed of a tooth group KU with a bite, a group of finishing teeth SI, and a group of flank teeth NI. However, in this example, in the finishing tooth group SI, a primary finishing tooth group SI- consisting of straight teeth T ₀ with constant tooth thickness in the tooth trace direction is formed on the side of the tooth group with bite, while a relief tooth group On the NI side, the same taper as before, that is, the crown tooth preparation tooth,
A secondary finishing tooth group SI consisting of T ₁ or T ₂ is formed. As is clear from the fact that these tapered teeth T ₁ and T ₂ are given the same reference numerals as those in FIG. 4, their taper directions are opposite.

On the other hand, a pair of flat dies 3a, 3 according to the second embodiment
b indicates the finished tooth group SI, which is divided into a primary finished tooth group SI consisting of straight teeth T ₀ as in the first embodiment, and a secondary finished tooth group SI consisting of twisted teeth, that is, crown tooth preparation teeth, T ₁ ′ or T ₂ ′. It consists of a finishing tooth group SI. The torsional direction of these helical teeth T ₁ ′ and T _{2 ′} is similar to that shown in the second conventional example in FIG. The helical tooth T 2 ' has a helix angle of the tooth trace that is larger by β, and conversely, the helical tooth T ₂ ' has a helix angle of the tooth trace that is smaller by some angle β than the helix angle of the tooth of the workpiece.

In both the first and second embodiments, if the workpiece is rolled using these flat dies 3a and 3b, as shown in FIG. 14, in the finished tooth group SI, Primary finishing tooth group SI
Due to the straight tooth T ₀ , the thickness dimension of the tooth 4a of the workpiece is reduced from the pre-processing dimension w ₁ to w ₂ .
This tooth thickness dimension _w2 is approximately equal to the tooth thickness dimension to be finally applied to the tooth 4a of the workpiece, that is, the dimension of the central portion of the tooth.

Next, as shown in FIG. 14, each flat die 3
Tapered tooth T ₁ of secondary finishing tooth group SI- of a and 3b,
The corner portion is machined by T ₂ or the twisted teeth T ₁ ′, T ₂ ′, and the machining allowances D and D′ are removed. That is, since each tooth T ₁ , T ₂ ; T ₁ ′, T ₂ ′ acts only on the corner portion of the tooth surface of tooth 4a, the machining allowances D and D′ are clear when compared with FIG. 11. It has become very small.
In other words, these teeth T ₁ , T ₂ ; Teeth 4a of T ₁ ′, T ₂ ′
In other words, the machining load on the tooth 4a is small, and the run-out and vibration of the workpiece 4 during machining is alleviated, and the machining accuracy of the workpiece is improved accordingly. becomes better.

Crown tooth 4a created by rolling using a flat die according to the first embodiment and the second embodiment
is as shown in FIG. i.e. tooth 4
The side surface of a is composed of tooth surfaces 4c and 4b on both sides created by teeth T ₁ , T ₂ ; T ₁ ′, T ₂ ′, and a tooth surface 4 d created by straight tooth T ₀ . Therefore,
Strictly speaking, this tooth surface is composed of three curved surfaces, and is not a single curved surface as in the conventional example shown in Figs. Since the amount of bulge is only about 10μ, these 3
A curved surface consisting of two curved surfaces is infinitely close to the above-mentioned one curved surface. This curved surface causes the central portion of the tooth surface to bulge out from both end portions of the tooth surface. In other words, the purpose of the crown tooth, which is to set both ends of the tooth surface back from the center of the tooth surface, has been fully achieved.

As described above, in any of the embodiments, it is possible to achieve the object of improving the machining accuracy of the workpiece by alleviating the phenomenon of shake or vibration of the workpiece 4 during rolling.

As a modification of the present invention, in the finished tooth group SI, a final finished tooth group consisting of straight teeth T ₀ may be further provided after the crown tooth forming tooth group SI-, that is, on the flank tooth group NI side. In this way, it is possible to correct the center part of the tooth 4a of the workpiece, which is created by the crown tooth preparation tooth group SI-, and whose center part is slightly bulging, resulting in even more accurate machining. It can be performed.

[Brief explanation of drawings]

Figure 1 is a perspective view of a tooth such as a gear having crown teeth, Figure 2 is a sectional view taken along the line of Figure 1, and Figure 3 is a special tooth for rolling the gear etc. having the teeth of Figure 1. 4th perspective view of essential parts of an imaginary flat die having
The figure shows a pair of flat dies 3a and 3b according to a first conventional example.
FIG. 5 is a plan view of a pair of flat dies 3a, 3b according to a second conventional example, and FIG. 6 is a method of rolling a workpiece 4 such as a gear using the flat dies 3a, 3b. FIG. 6 is a right side view of FIG. 6, FIG. 7 is an explanatory diagram showing the overlapping state of the pair of flat dies 3a and 3b according to the first conventional example, and FIG. 8 is a right side view of FIG. A pair of flat dies 3 according to the conventional example
Fig. 9 is a diagram illustrating the overlapping of dies 3a and 3b, and Fig. 9 is a diagram illustrating the run-out or vibration of the workpiece 4 that occurs when the workpiece 4 is rolled using the flat dies 3a and 3b according to the first conventional example. An explanatory diagram, FIG. 10 is an explanatory diagram for explaining the deflection or vibration of the workpiece 4 that occurs when the workpiece 4 is processed using the pair of flat dies 3a, 3b according to the second conventional example. Figure 11 shows tapered teeth according to the first and second conventional examples.
T ₁ , T ₂ or twisted teeth T ₁ ′, T ₂ ′ are teeth 4 of the workpiece
Explanatory diagram showing the state of rolling processing for a, 1st
2 to 15 show embodiments of the present invention, FIG. 12 is a plan view of a pair of flat dies 3a, 3b according to the first embodiment, and FIG. 13 is a plan view of a pair of flat dies 3a, 3b according to the second embodiment. The plan view, Fig. 14, is the above-mentioned No. 1
and a pair of flat dies 3a according to the second embodiment,
15 is an explanatory view showing the process of machining the teeth 4a of the workpiece using the first and second flat dies 3a and 3b. FIG.
It is a perspective view showing the tooth surface of. 3a, 3b... A pair of flat dies, 4... Workpiece (gear), 4a... Teeth of workpiece 4, KU... Teeth group with bite, SI... Finishing tooth group, NI... Relief tooth group, SI -... Primary Finished tooth group, SI-...Secondary finished tooth group, _T0 ...Straight tooth, _T1 , _T2 ...Tapered tooth, _T1 ', _T2 '...Twisted tooth.

Claims (1)

[Claims] 1. The finishing tooth group of each flat die has a constant tooth thickness in the tooth trace direction, and acts on each tooth of the workpiece to uniformly reduce the tooth thickness as a whole. A primary finishing tooth group consisting of straight teeth, and a tooth at each side corner of each tooth of the workpiece, which is disposed subsequent to the primary finishing tooth group and whose tooth thickness is reduced overall by the primary finishing tooth group. A pair of flat dies for rolling crown teeth, comprising a secondary finishing tooth group consisting of crown tooth preparation teeth that act to further reduce the tooth thickness at each corner portion. 2 The secondary finishing tooth group of one of the flat dies consists of tapered teeth whose tooth thickness decreases from one side of the flat die to the other side, and the secondary finishing tooth group of the other flat die is 2. The flat die for crown tooth rolling according to claim 1, characterized in that the die has tapered teeth whose tooth thickness decreases from the other side toward the one side. 3 The secondary finishing tooth group of one of the flat dies consists of teeth having a tooth helix angle slightly larger than the tooth helix angle of the workpiece, and the secondary finishing tooth group of the other flat die consists of teeth having a tooth helix angle slightly larger than that of the workpiece. 2. The flat die for crown tooth rolling according to item 1, characterized in that the die has teeth having a tooth trace helix angle slightly smaller than the tooth trace helix angle of an object.