JP2007167899A - Rolling-forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling-forming method with which the variation of a phase in a rolling die caused by a backlash of a speed reducer is removed by using a correcting movement with a simple program. <P>SOLUTION: In the rolling-forming method for forming a gear tooth on the outer surface of a blank with two round dies, when this forming method is applied by alternately changing the rotating direction of the two round dies into the normal rotation and the reverse rotation, mutual phase error is decided based on a second die phase at the time of matching the phase to the second die under the normal rotating operation in a first die put to the standard angle, and the second die phase at the time of matching the phase to the second die under the reverse rotating operation in the first die put to the standard angle. Then, in the formation of the gear tooth at the time of changing from the normal rotation to the reverse rotation or from the reverse rotation to the normal rotation, a main shaft rotating angle of the first die and a main shaft rotating angle of the second die are corrected according to the mutual phase error. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling forming method for removing a phase change of a rolling die caused by a backlash of a speed reducer by forming a rolling gear or the like by a correction operation using a simple program.

  Rolled screws are formed by round die type, flat die type and planetarium type rolling machines, and a plurality of rotating dies are pressed against a material to form a thread. Rolling gears can be formed on the same rolling machine as that used for forming rolling screws. Especially, round die type rolling machines are excellent in strength, precision, and dimensional variation. Widely used as a rolling machine suitable for obtaining small rolling gears. The two rolling dies used in this round die rolling machine have the same shape, and both form gear teeth on the material surface while rotating in the same direction and at the same speed.

  By the way, in the forming of the rolling machine, the mounting position of the two rolling dies has a decisive influence on the machining accuracy, so adjustment of the mounting position is indispensable. An important adjustment is called phasing, where the material is placed between the rolling dies and eaten, and the material is rotated half a turn. Thereafter, the machine is reversed to take out the material from between the two rolling dies, and it is checked whether or not the pitches of the formed teeth are exactly the same. If they match, the relative position of the rolling die is accurate and does not need to be adjusted again. If they do not match, the relative position of the rolling die is adjusted.

  In the rolling machine, as shown in FIG. 9, the two main shafts 51 are arranged on the same plane, and a round die 52 is attached to each of the main shafts 51. The main shaft 51 is connected to a servo motor 53 for rotating two round dies 52 in the same direction and at the same speed. In order to keep the spindle speed at a desired value, a speed reducer 54 is provided between the two. Generally, the speed reducer 54 includes a worm and a worm wheel. Similarly, a rolling machine using two round dies is described in Japanese Patent Laid-Open No. 11-285761 (Patent Document 1). The rolling machine disclosed herein details the forming of the rolling screw.

  By the way, in forming the rolling gear, a forming method is used in which the rotation direction of the main shaft 51 is alternately changed from normal rotation to reverse rotation and from reverse rotation to normal rotation. Tooth surfaces rolled by this forming method have the advantage that better accuracy can be obtained by equalizing the pressure acting on the workpiece during rolling, compared to those where alternating conversion is not performed, and many rolling gears Used in molding. However, according to this molding method, the phase of the round die 52 changes every time the forward rotation is reversed and the reverse rotation is converted to the forward rotation due to backlash inevitably occurring in the speed reducer 54 connected to the main shaft 51. As a result, the adjusted phase alignment is out of order.

An example of means for automatically correcting a phase alignment error that occurs during molding is described in Patent Document 1 described above. This is achieved by providing a rotation angle detection means such as a rotary encoder on each main shaft, and feeding back the detected rotation angle signal to the rolling die rotation control means to control the rotation of the servo motor.
Japanese Patent Laid-Open No. 11-285761, (page 3-4, FIG. 1-2)

  The required accuracy of the thread surface of the rolling screw formed by a round die type rolling machine is on the order of 100 to several hundreds of μm, and the phase change due to the backlash of the reduction gear has not been regarded as a problem. However, if the rolling gear is to be formed on the same rolling machine, the phase change due to backlash greatly affects the tooth surface accuracy, and this cannot be ignored.

  In recent years, the required tooth surface accuracy of a rolled gear has been required to be higher than the normal gear tooth surface accuracy, such as a tooth trace error of about 10 μm, like the worm of an electric power steering reduction gear. The tooth trace error corresponds to a phase of a rolling die used in a rolling machine and is approximately 0.0017 ° (a value calculated assuming that the gear specifications of the worm are the same as those in the test described later).

  In order to satisfy the requirement that the tooth trace error is about 10 μm, it is important to minimize the phase change of the rolling die that occurs during the rolling process, but no advantageous solution has been found. An apparatus for controlling the rotation of the servo motor by providing a rotation angle detection means on each of the main shafts can automatically remove the phase change of the rolling die due to backlash, and this method is also effective. However, it is inevitable that the control device becomes expensive by incorporating such detection means, and a simpler method is demanded.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling forming method that can remove a phase change of a rolling die caused by a backlash of a reduction gear by a correction operation using a simple program.

The rolling forming method according to the present invention is a rolling forming method for forming gear teeth or a thread on the outer surface of a material with two round dies, and the rotational directions of the two round dies are forward rotation and reverse rotation. When the first die is rotated at the reference angle and the second die is phase-adjusted by the forward rotation operation at the reference angle, the second die phase θ ₁ and the first die are rotated at the reference angle by the reverse operation. The mutual phase error E is determined on the basis of the phase θ ₂ of the second die when the two dies are phase-matched, and the gear teeth or threads are formed when converted from normal rotation to reverse rotation and from reverse rotation to normal rotation. The first die spindle rotation angle and the second die spindle rotation angle are corrected according to the mutual phase error E.

Although it is desirable that the backlash of the speed reducer incorporated in the rolling machine is minimal, the backlash cannot be reduced to zero. The reduction gear backlash can be easily measured if phase matching is actually performed using two rolling dies. Hereinafter, a method for obtaining the phase difference by the conversion from the normal rotation to the reverse rotation and from the reverse rotation to the normal rotation using the two round dies, that is, the first die D ₁ and the second die D ₂ shown in FIG. 1 will be described.

A workpiece is placed between the first die D ₁ and the second die D _2, and the tooth tip of the first die D ₁ is copied to the workpiece by forward rotation of the die, and the tooth tip of the second die D ₂ is copied to the workpiece ( The carved muscle on the workpiece is the tooth bottom). When the dice phase is matched in the forward operation, the streaks transferred onto the work are connected to one. Strictly has occurred slight differences between the dies, between the first die D ₁ and the second die D _2, as shown in FIG. 2 (a), serving as a reference of the first die D ₁ If the phase is 0 °, the phase difference in the forward rotation operation can be found on the second die D ₂ as the phase θ ₁ .

Also for the reverse rotation operation, a work is placed between the first die D ₁ and the second die D ₂ and the tooth tip of the first die D ₁ is copied to the work, and the tooth tip of the second die D ₂ is copied to the work. When the dice phase is matched by the reverse operation, the streaks transferred onto the work are connected to one. At this time, if the phase of the reference first die D ₁ is 0 ° between the first die D ₁ and the second die D ₂ as shown in FIG. A phase difference can be found as phase θ ₂ on the second die D ₂ .

After all, the mutual phase error E between the first die D ₁ and the second die D ₂ is
E = | θ ₁ −θ ₂ |
Can be obtained as

  In the present invention, the first die spindle rotation angle and the second die spindle rotation angle are corrected according to the mutual phase error E in each of forward rotation and reverse rotation.

As a result, the phases of both the first die D ₁ and the second die D ₂ are matched from the point of time when the rotation is changed from normal rotation to reverse rotation and from reverse rotation to normal rotation by the correction operation given during the rolling gear or rolling screw forming. It becomes possible to remove the phase change caused by the backlash.

  In addition, when the present invention is executed, the angle of the second die when the computer rotates the first die with the normal rotation operation at the reference angle and the second die is phase-adjusted, and the reverse operation with the first die at the reference angle. In the step of determining the mutual phase error based on the phase of the second die when the second die is phase-adjusted, and in the gear tooth forming when converting from forward rotation to reverse rotation and from reverse rotation to normal rotation, A program for controlling the rolling forming of the worm using the rolling forming method including the step of correcting the die main shaft rotation angle and the second die main shaft rotation angle according to the mutual phase error is included.

  Furthermore, the present invention includes a storage medium storing a program for controlling the worm roll forming using the above roll forming method when the computer is executed.

  An embodiment of the rolling molding method according to the present invention will be described. As shown in FIG. 3, the round die type rolling machine to which the method of the present invention is applied has two main shafts 1a and 1b, and a round die is attached to each of the main shafts 1a and 1b. In order to distinguish the two round dies, one is called a first die 2a and the other is called a second die 2b. The first die 2a and the second die 2b are rotated in the same direction and at the same speed by servo motors 3a and 3b for driving the main shafts 1a and 1b, respectively. Reducers 4a and 4b are provided between the main shafts 1a and 1b and the servo motors 3a and 3b to reduce the main shaft speed to a relatively low speed.

  Further, the round die type rolling machine is provided with a control device 5 for controlling servo motors 3a and 3b, an actuator of a pushing mechanism (not shown), and the like. The servo motors 3a and 3b are controlled by a position control controller 6 shown in FIG. The controller 6 includes a computer 7 composed of a CPU and a memory, and data stored in the memory is processed by the CPU according to a program. The calculation result by the CPU is output to the servo driver, and the servo motors 3a and 3b are rotated in accordance with the command.

  A procedure for rolling and forming a worm according to the method of the present invention will be described. As shown in FIG. 5, the worm 8 is a screw-like gear and includes a large number of teeth 9. Data necessary for the rolling forming of the worm 8 is given to the computer 7 from a storage medium (for example, CD-ROM), and the following successive steps are executed.

  In FIG. 6, in the rolling processing condition input, processing conditions such as the spindle rotation direction, the rolling pressure, and the number of rolling are input (step 101). In gear data input, gear data such as the number of threads, module, pressure angle, lead, tip diameter, root diameter, and twist direction are input (step 102). In the mutual phase error input, a mutual phase error E obtained by performing phase alignment using a rolling die actually used is input (step 103).

  The reverse rotation of the first die and the second die is determined by collating with the spindle rotation direction given by the rolling process condition input (step 104). In accordance with the mutual phase error E, the first die spindle rotation angle and the second die spindle rotation angle at the time of reverse rotation are calculated (step 105).

  Similarly, normal rotation of the first die and the second die is determined by collating with the spindle rotation direction given by the rolling process condition input (step 106). In accordance with the mutual phase error E, the first die spindle rotation angle and the second die spindle rotation angle during forward rotation are calculated (step 107).

  A first die spindle rotation control command and a second die spindle rotation control command are output based on the first die spindle rotation angle and the second die spindle rotation angle at the time of reverse rotation obtained in the above step (step 108). Further, a first die spindle rotation control command and a second die spindle rotation control command are output based on the first die spindle rotation angle and the second die spindle rotation angle during forward rotation (step 109).

  In this way, since the phases of both the first die 2a and the second die 2b are matched from the point of time when the normal rotation is reversed to the reverse rotation and the reverse rotation to the normal rotation by the correction operation given during the rolling forming of the worm, It is possible to remove the change in phase.

  Tooth trace error was measured using a gear testing machine. For comparison, a worm according to the prior art that does not remove the influence of backlash was also produced for comparison, and the tooth trace error was measured under the same conditions.

Example 1
A worm was produced according to the method of the present invention using a round die rolling machine. The worm material was S45C, and a tempered material was used. Table 1 shows the gear specifications of the worm.

（比較例１）
バックラッシュの影響を除かないウォームを作製した。ウォーム材質はＳ４５Ｃで、調質材を用いた。

(Comparative Example 1)
A worm that does not remove the effect of backlash was produced. The worm material was S45C, and a tempered material was used.

(Measurement result)
The measurement results of each worm are shown in FIGS. The X-axis of each graph is the direction along the tooth trace, with the start point (left side) corresponding to the root and the end point (right side) corresponding to the tooth tip. The Y axis represents the degree of swell. The graph depicts the undulation from the root to the tip of the three selected worm teeth (total 6 tooth surfaces). It can be seen that the tooth trace error is very large due to the prior art and the tooth surface accuracy is low. On the other hand, as shown in FIG. 7, the product rolled by the method of the present invention has a small undulation from the root to the tip of the tooth, and it can be seen that the tooth surface accuracy is remarkably excellent. In comparison between Example 1 and Comparative Example 1, an accuracy improvement of 0.02 mm was found in the tooth trace direction error.

  This is useful for forming the gear teeth of the rolling gear by removing the phase change of the rolling die due to the backlash of the reduction gear.

It is a schematic diagram which shows the arrangement | positioning relationship of the 1st die | dye which concerns on this invention method, and a 2nd die. It is a figure explaining the phase alignment of the 1st die and the 2nd die by the present invention, (a) is a figure explaining the phase difference between the dies at the time of forward rotation, (b) is between the dies at the time of reverse rotation It is a figure explaining a phase difference. It is a block diagram which shows the principal part of the rolling machine which concerns on this invention method. It is a block diagram which shows the controller which controls the rolling die based on this invention method. It is a perspective view which shows an example of the worm formed by rolling by the method of the present invention. It is a flowchart which shows the rolling forming procedure of the worm | warm by this invention. It is a graph showing the tooth trace error measured value of the worm shape | molded according to this invention method. It is a graph showing the tooth trace error measured value of the worm | mold shape | molded without using this invention method. It is a perspective view which shows the die | dye attached to the conventional rolling machine.

Explanation of symbols

1a, 1b ... Spindle 2a ... 1st die 2b ... 2nd die 3a, 3b ... Servo motor 4a, 4b ... Reducer 5 ... Control device 6 ... Controller 7 ... Calculator 8 ... Warm

Claims (3)

A rolling forming method for forming gear teeth or a thread on the outer surface of a material with two round dies, wherein the rotation direction of the two round dies is alternately converted into normal rotation and reverse rotation. At this time, the second die angle θ ₁ when the second die is phase-adjusted by the forward rotation operation at the reference angle of the first die and the second die is phase-adjusted by the reverse operation of the first die at the reference angle. The mutual phase error E is determined on the basis of the phase θ ₂ of the second die when the first die is rotated, and the first die spindle is rotated in the formation of gear teeth or threads when converted from forward rotation to reverse rotation and from reverse rotation to normal rotation. A rolling forming method, wherein the angle and the second die spindle rotation angle are corrected according to the mutual phase error E.   When executed, the computer (a) the angle of the second die when the second die is phase-adjusted with the forward rotation operation at the reference angle of the first die, and the reverse operation of the first die with the reference angle at the reference angle. A step of determining a mutual phase error based on the phase of the second die when the second die is phase-matched, and (b) in forming gear teeth when converted from normal rotation to reverse rotation and from reverse rotation to normal rotation. A program for controlling roll forming of a worm using a roll forming method having a step of correcting a first die spindle rotation angle and a second die spindle rotation angle according to the mutual phase error. A storage medium storing a program for controlling the worm roll forming, wherein the computer uses the roll forming method according to claim 2 when executed.

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