WO2022224291A1

WO2022224291A1 - Hobbing machine

Info

Publication number: WO2022224291A1
Application number: PCT/JP2021/015791
Authority: WO
Inventors: 柳崎淳; 熊崎信也
Original assignee: 株式会社Fuji
Priority date: 2021-04-19
Filing date: 2021-04-19
Publication date: 2022-10-27
Also published as: JPWO2022224291A1

Abstract

This hobbing machine maintains processing accuracy while shortening processing time, the hobbing machine including: a workpiece spindle device which applies rotation to a held workpiece; a hob driving device which rotates a hob cutter having an axis of rotation in a direction intersecting the axis of rotation of the workpiece, while moving the hob cutter in a direction along the axis of rotation of the workpiece; and a control device which controls the workpiece spindle device and the hob driving device, the control device changing the feed speed when moving the hob cutter relative to the hob driving device according to processing positions of the workpiece, such as a starting position where the hob cutter first makes contact with the workpiece, an intermediate position where the axis of rotation of the hob cutter overlaps the workpiece in a direction orthogonal to the axis of rotation, and an end position where the hob cutter separates from the workpiece, for example.

Description

hobbing machine

The present invention relates to a hobbing machine that reduces machining time while maintaining machining accuracy.

When gear cutting a workpiece with a hobbing machine, there is a problem that the machining accuracy decreases due to fluctuations in the machining load relative to the rotation of the hob. Patent Literature 1 listed below discloses an invention that solves the problem of errors occurring in the tooth trace direction as one of the problems. In the hobbing machine, the hob and table are rotated synchronously, and the hob is fed parallel to the axis of the workpiece to perform hobbing. At that time, the machining resistance acts as a load on the rotation of the hob, and the machining resistance changes as the machining progresses. This is because mechanical deformation such as bending and twisting occurs in the components of the transmission system between the hob and the table, which affects the rotation phase between the hob and the table. Therefore, in the hobbing machine of the same document, attention is paid to the fact that the current value of the hob drive motor fluctuates according to the load fluctuation with respect to the rotation of the hob. By calculating the correlation value of the error in the direction of the streak and giving a correction rotation to the table, the error in the direction of the tooth streak of the workpiece is resolved.

JP-A-59-81017

Gear cutting of a workpiece performed by a hobbing machine has not only the problem of errors in the direction of tooth traces of the workpiece as in the conventional example, but also problems of machining accuracy and machining time. In hobbing, cutting feed is one of the major parameters that determines the machining accuracy and machining time. Usually, the feed rate is lowered to improve the machining accuracy, but this increases the machining time. On the other hand, although the feed rate is increased in order to shorten the machining time, the machining accuracy is lowered.

Therefore, in order to solve such problems, an object of the present invention is to provide a hobbing machine that shortens the machining time while maintaining the machining accuracy.

A hobbing machine according to one aspect of the present invention includes a work spindle device that rotates a held work, and a hob cutter having a rotation axis that intersects the rotation axis of the work. It controls a hob driving device that moves in a direction along the rotation axis, the work spindle device and the hob driving device, and the feed speed when moving the hob cutter with respect to the hob driving device is controlled by the work. and a control device that changes according to the machining position with respect to.

According to the above configuration, the workpiece is held by the workpiece spindle device and rotated, while the hob cutter of the hob driving device rotates and moves in the direction along the rotation axis of the workpiece, thereby performing gear cutting on the workpiece. done. At that time, since the feed speed of the hob cutter is changed by the control device, for example, by increasing the feed speed within a range in which the processing is stabilized, it is possible to shorten the processing time while maintaining the accuracy of the entire processing.

It is an appearance perspective view showing one embodiment of a hobbing machine. It is a perspective view showing the internal structure about one embodiment of a hobbing machine. It is a block diagram showing the control system of the hobbing machine. It is the figure which simply showed the positional relationship and feed speed of the workpiece|work W and a hob cutter. 4 is a perspective view showing a hob cutter for a work W; FIG.

An embodiment of a hobbing machine according to the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view showing the hobbing machine of this embodiment, and FIG. 2 is a perspective view showing the internal structure of the hobbing machine of this embodiment. The hobbing machine 1 is mounted on a movable bed 11 having wheels and is movable in the front-rear direction along rails 3 fixed to the upper surface of the base 2 . The hobbing machine 1 is modularized together with other working machines such as a lathe, and is configured with a width dimension that matches a base 2 that serves as a reference.

The hobbing machine 1 is one work machine that constitutes a processing machine line, and multiple work machines lined up are covered with an exterior cover that has a uniform appearance. An openable and closable front cover 4 forms a transfer space 5 in the outer cover, and an autoloader for transferring a work to each work machine is incorporated therein. Specifically, a work transfer robot 6, which is a multi-joint robot arm, is movable in the width direction of the machine body along a guardrail constructed in the front part of the base 2. As shown in FIG. In this embodiment, the longitudinal direction of the machine body is the X-axis, the width direction of the machine body is the Y-axis, and the vertical direction is the Z-axis.

In the hobbing machine 1, a column 12 on a movable bed 11 is movable in the longitudinal direction of the machine body in the X-axis direction. It is configured to be raised and lowered by a shaft motor 15 . A hob head 16 that supports a hob cutter 17 is assembled to the saddle 13 . The hob cutter 17 is rotatably supported by a horizontal rotating shaft parallel to the Y-axis, and is rotated during gear cutting by a hob motor 19 (see FIG. 3). The hob head 16 is structured to be movable in the Y-axis direction with respect to the saddle 13 by a Y-axis motor 18 so that the position of the blade of the hob cutter 17 can be changed.

A work spindle device 20 is provided on the front side of the hob driving device on which the hob cutter 17 is mounted. The work spindle device 20 is configured vertically such that a lower unit 21 and an upper unit 22 are coaxial with the center of rotation aligned with the Z-axis. A support column 23 is erected on the movable bed 11 to constitute a lift mechanism for moving the upper unit 22 up and down in the Z-axis direction. A vertical rail is fixed to the support column 23, and a lift 24 holding the upper unit 22 is slidably assembled thereon. A lift motor 25 is provided at the top of the support column 23, and its rotational output is converted into linear motion of the lift 24 by a ball screw.

The lower unit 21 has a lower clamp block that sandwiches the workpiece W between itself and the rotatable upper clamp block of the upper unit 22. The rotation of the workpiece rotating motor 27 is transmitted to the lower clamp block via a worm gear. configured to be The hobbing machine 1 is mounted on the movable bed 11 with a control device 30 for controlling each driving part arranged behind a hob driving device composed of a column 12 and the like. FIG. 3 is a block diagram showing the control system of the hobbing machine 1. As shown in FIG.

A microprocessor (CPU) 31, a ROM 32, a RAM 33, and a nonvolatile memory 34 are connected to the control device 30 via bus lines. The CPU 31 controls the entire control device, the ROM 32 stores system programs executed by the CPU 31, control parameters, and the like, and the RAM 33 stores temporary calculation data, display data, and the like. The non-volatile memory 34 stores information necessary for processing performed by the CPU 31, and stores a sequence program for the hobbing machine 1 and the like. In particular, the non-volatile memory 34 of this embodiment also stores a hobbing program and the like, which will be described later.

As shown in FIG. 1, the hobbing machine 1 is equipped with a touch panel type operation display device 38 on the front part of the machine body, which enables the operator to perform input operations and display the manufacturing status on the screen. The controller 30 is provided with an I/O port 35 through which an operation display device 38 and the like are connected. Further, the I/O port 35 is connected to

drivers

41, 42, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 42, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43. 44 and 45 are connected.

For gear cutting on the hobbing machine 1, the workpiece W carried into the machining chamber by the workpiece transfer robot 6 is placed on the lower unit 21 of the workpiece spindle device 20. In the work spindle device 20, the upper unit 22 held by the lift 24 is lowered by driving the lift motor 25, and the work W is held by the upper and lower clamp blocks by the clamping operation with the lower unit 21. After the workpiece spindle device 20 is ready for machining the workpiece W, the clamped workpiece W is rotated by driving the workpiece rotation motor 27 . Then, the hob cutter 17 is rotated and moved in the Z-axis direction by driving the hob driving device, and the rotating workpiece W is subjected to gear cutting.

Here, FIG. 4 is a diagram simply showing the positional relationship between the work W and the hob cutter 17 and the feed speed. In the gear cutting of the work W, the hob cutter 17 moves linearly in a direction parallel to the Z-axis while rotating around the rotation axis Oy in the Y-axis direction, while the work W moves around the work rotation axis Oz in the Z-axis direction. and rotate. Therefore, as shown in FIG. 4, the hob cutter 17, which applies the hob blade 171 to the rotating work W, gradually moves from A to D while the gear cutting process proceeds.

In conventional gear cutting, the feed speed in the Z-axis direction of the hob cutter 17 was constant between A and D. Therefore, as mentioned above, machining accuracy and shortening of machining time are incompatible. There is a problem that the accuracy is lowered. Therefore, in this embodiment, a hob feed program for adjusting the feed speed of the hob cutter 17 is provided so that the machining time can be shortened while maintaining the machining accuracy.

5 is a perspective view showing the hob cutter 17 for the work W. FIG. The hob cutter 17 has a helically formed hob blade 171 that is discontinuous in the circumferential direction due to a plurality of blade grooves 173 cut in the axial direction. Therefore, intermittent contact of the hob blade 171 with the work W makes it difficult to increase the feed rate while maintaining the machining accuracy. In particular, the large variation in machining load around position A at the start of machining, where only the tip of the hob blade 171 is in contact, has been a cause of reduced machining accuracy due to an increase in feed rate.

On the other hand, when the hob cutter 17 moves to position B in FIG. At this time, the discontinuous hob blades 171 that move back and forth in the rotational direction simultaneously act on the workpiece W, so that the influence of the discontinuity of the hob blades 171 is reduced and the machining load fluctuation is reduced. For this reason, it is considered that the way in which the hob cutter 17 contacts the workpiece W changes as it moves in the Z-axis direction, changing from an unstable machining state to a stable machining state. Therefore, if the machining state of the hob cutter 17 is stable, a certain machining accuracy can be obtained even if the feed rate is increased.

In the hob feed program of this embodiment, the feed speed of the hob cutter 17 is set to change according to the feed amount of the hob blade 171 . Specifically, the feed rate is changed as the position of the tool rotation axis Oy of the hob cutter 17 moves between AB, BC and CD shown in FIG. ing. Position A is the position at which the hob cutter 17 begins contact with the work W, Position B and Position C are positions at which the tool rotation axis Oy overlaps the work W in the orthogonal direction, and Position C is the position where the hob cutter 17 touches the work W. It is a position away from W. The feed speed between BC is constant, and the feed speed between AB and between CD is obtained based on the following formulas (1) and (2).

fa−b=fa+{(fb−fa)/(B−A)}×Z1 (1)
fc−d=fc+{(fc−fd)/(C−D)}×Z2 (2)
Here, fn represents the feed speed at an arbitrary position in the Z-axis direction such as the A position and the B position, and the feed speed in an arbitrary range in the Z-axis direction such as between AB (n is an arbitrary position and range). A, B, C, and D are coordinate values of the hobbing machine 1 in the three-dimensional space in the Z-axis direction. Z1 and Z2 are feed amounts in the Z-axis direction of the hob cutter 17 based on the tool rotation axis Oy, Z1 is a variable based on the A position, and Z2 is a variable based on the C position.

In addition, the feed speed of the hob cutter 17 depends on various factors such as the material and size of the work W, the size and shape of the hob blade 171, and the depth of work W to be machined. , fb, fc, and fd are arbitrarily determined. At this time, the relationship of each feed rate is fb=fb-c=fc, fa<fb, fc>fd. In the graph shown in FIG. 4, the feed speed fa and the feed speed fd are shown to match, but they are simply expressed and do not necessarily match.

The coordinate values A, B, C, and D and the feed speeds fa, fb, fc, and fd in accordance with the workpiece W in the equations (1) and (2) are used for gear cutting of the corresponding workpiece W. input from the operation display device 38 by the operator. From the equations (1) and (2), in the gear cutting of this embodiment, the value of Z1 increases as the hob cutter 17 moves during machining between A and B, and the value of the feed rate fa-b is (1 ) increases from fa to fb according to the equation. Also, during machining between CD, the value of the feed rate fc-d decreases from fc to fd according to the equation (2).

Specifically, first, as shown in FIG. 5, at position A where the tip of the hob blade 171 hits the workpiece W, machining is started at the feed speed fa. Then, the feed speed gradually increases as the feed amount Z1 of the hob cutter 17 changes when the tool rotation axis Oy moves from the A position to the B position. That is, at the beginning of machining where the contact of the hob blade 171 changes and the machining load fluctuates greatly, the feed rate is relatively low, and as the hob blade 171 approaches the position B where the hob blade 171 enters deeply into the workpiece W, the machining load fluctuation decreases. Therefore, the feed speed fa-b gradually increases.

Next, from the B position to the C position, the machining load fluctuation is small and machining is stable, so the feed speed fb-c (=fb) is the largest and constant. From the C position, the contact of the hob blade 171 changes again and the machining load fluctuation increases. -d becomes smaller.

Therefore, according to the present embodiment, since the feed speed is changed according to the characteristics at the time of work processing in the hob cutter 17, the processing time is shortened by increasing the feed speed between B and C, where the processing load fluctuation is particularly small. becomes possible. In addition, since the feed speed is changed between AB and between CD where machining load fluctuations are large, machining accuracy can be maintained while shortening the overall machining time.

Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, the feeding speed between BC is constant, but the feeding speed during this period may also be changed.

DESCRIPTION OF SYMBOLS 1... Hobbing machine 12... Column 13... Saddle 15... Z-axis motor 17... Hob cutter 18... Y-axis motor 20... Work spindle device 27... Work rotation motor 30... Control device

Claims

a work spindle device that rotates the held work;
A hob driving device that moves the hob cutter in a direction along the rotation axis of the work while rotating the hob cutter having a rotation axis that intersects the rotation axis of the work;
a control device that controls the work spindle device and the hob drive device, and changes the feed speed when moving the hob cutter with respect to the hob drive device according to the machining position with respect to the work;
A hobbing machine having a
The control device adjusts the feed speed based on the start position of the hob cutter at the beginning of contact with the work, the intermediate position where the rotation axis of the hob cutter overlaps the work in the orthogonal direction, and the end position where the hob cutter leaves the work. The hobbing machine of claim 1, wherein the hobbing machine is variable.
The control device changes the feed rate so that it is accelerated from the start position to the intermediate position, is constant during the intermediate position, and is decelerated from the intermediate position to the end position. Item 2. The hobbing machine according to item 2.