JPH06226531A - Gear shaping device - Google Patents

Abstract

PURPOSE:To provide a gear shaping device having the capability of inexpensively and yet efficiently machining the tooth space of different size and shape. CONSTITUTION:A tool main spindle 26 is caused to rotate on the operation of a servo motor 62 for tool rotation via a reduction gear train 70 and a shaft 68. The rotation of a servo motor 82 for tool travel is converted to linear motion via a ball screw 84 and a nut 86 for transmission to the spindle 26, thereby causing the travel thereof along a rotational center line. In the case of the rough machining of tooth space on a gear element, a front milling cutter 34 is mounted on the spindle 26 and shifted, while rotating, to perform the rough machining of the tooth space. The finish machining of the space is undertaken after changing the cutter 34 to a disc broach. According to this construction, the travel distance of the front milling cutter 34 and the disc broach can be arbitrarily adjusted by controlling the rotation of the motor 82. Furthermore, a relief section can be formed, and a correction or the like can be made, regarding crowing and tooth trace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cutting a helical gear such as a helical bevel gear and a hypoid gear, and more particularly to improving the degree of freedom in machining.

[0002]

2. Description of the Related Art There is an apparatus for processing a helical gear that processes a tooth groove by indexing a tooth groove processing position of a gear material and cutting a machining tool into the gear material. This type of gear machining apparatus generally includes (a) a machining tool capable of sequentially machining each tooth groove of a gear material, (b) a rotation drive device for rotating the machining tool, and (c) each tooth groove. An indexing device that rotates the gear material every angular interval between adjacent tooth spaces each time the cutting process of (1) is completed, and (d) a moving device that moves the processing tool along the rotation center line of the processing tool. Configured to include.

The gear machining apparatus described in Japanese Patent Publication No. 40-516 is an example. In this device, the moving device for moving the processing tool is constituted by a cam. The cam is rotated by a motor that rotates the processing tool through a large number of gears, and a roller as a cam follower is engaged with the cam. The roller is attached to one end of a lever rotatably attached to the frame. The lever rotatably supports the machining tool and can move in a direction parallel to the rotation center line of the machining tool. The block provided in the is urged by a spring to be engaged. Therefore, when the cam is rotated, the lever is rotated and the processing tool is moved along the rotation center line.

[0004]

When machining a tooth groove by rotating the machining tool along the rotation center line in this way and machining the tooth groove, the shape of the tooth groove to be machined by changing the moving distance of the machining tool. ， The dimensions can be changed. Therefore, when the moving device is configured by a cam, a cam that can obtain a desired moving distance depending on the shape and size of the tooth groove may be provided. However, the type of gear or the type of machining is changed. The shape and size of the tooth groove change due to factors such as the above, and it is necessary to change the cam every time it is necessary to change the moving distance of the processing tool, which requires multiple types of cams, resulting in higher equipment costs. Further, there is a problem that the machining time is long and the machining efficiency is reduced because the cam is replaced. It is an object of the present invention to provide a gear machining device that can efficiently machine various types of spiral gears having different shapes and dimensions at low cost and efficiently.

[0005]

In order to solve the above-mentioned problems, the present invention includes the above-mentioned (a) machining tool, (b) rotary driving device, (c) indexing device and (d) moving device. The moving device of the gear processing device includes an electric motor whose rotation amount is controllable, and a motion conversion device which converts the rotation of the electric motor into a movement along the rotation center line of the processing tool, and the rotation of the electric motor. The gist of the invention is to provide a control device for controlling the.

[0006]

The moving distance of the working tool can be changed by changing the rotation amount of the electric motor. Therefore, by controlling the amount of rotation of the electric motor, the tooth groove can be processed into a desired shape and size.

[0007]

As described above, according to the present invention, it is possible to machine various kinds of tooth spaces having different sizes and shapes only by changing the rotation amount of the electric motor, and the machining tool is moved by the cam as in the conventional case. Compared with the case where it is performed, the tooth groove can be processed at low cost and efficiently.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a gear cutting machine for a helical bevel gear will be described below in detail with reference to the drawings. In FIG. 2, reference numeral 10 is a bed, and a work headstock 12 and a tool headstock 14 are provided on the bed 10. A work spindle 16 is rotatably held on the work spindle stock 12. The work spindle 16 extends in the horizontal direction and is intermittently rotated about its own axis by a constant angle by an indexing motor 18. The indexing motor 18 and the device for transmitting the rotation of the indexing motor 18 to the work spindle 16 constitute the indexing device. A collet chuck (not shown) is attached to the projecting end of the work spindle 16 from the work headstock 12 so that the gear material 20 is held in an arbitrary phase. It is rotated integrally with the rotation of the main shaft 16. The gear material 20 has a tooth groove rough-processed as described later, and has a truncated cone-shaped processed portion.

The frame 24 of the tool headstock 14 is shown in FIG.
As shown in, the tool spindle 26 is rotatably held via a pair of stroke ball bearings 28 and 30. The stroke ball bearings 28 and 30 are bearings that allow the tool spindle 26 to rotate and move along the rotation center line. The tool spindle 26 projects from the tool spindle stock 14 in a state of facing the workpiece spindle 16, and the projecting end portion holds the machining tool.

As a machining tool, a front milling cutter 34 is used during rough machining, and a disc broach 36 shown in FIG. 3 is used during finishing machining. As shown in FIG. 1, the front milling cutter 34 has a disk-shaped tool body 38 to which the same number (for example, 8 pieces) of outer blades 40 and inner blades 42 are fixed (one piece in the figure). It is shown). In the disc broach 36, as shown in FIG. 3, the same number (for example, four) of outer blades 48 and inner blades 50 are alternately fixed to a disc-shaped tool body, but the tool body has outer blades. There is provided an indexing region W to which the 48 and the inner blade 50 are not attached, and the workpiece is intermittently rotated by the workpiece spindle 16 in a state where the indexing region W faces the workpiece, so that the workpiece is Will be indexed. Also, the outer blade 48
The cutting edge 52 of the disk is farther from the indexing area W in the direction opposite to the rotation direction indicated by the arrow A of the disc broach 36,
The distance from the center of the tool body gradually increases, and the cutting edge 54 of the inner blade 50 is fixed so as to gradually decrease.

As shown in FIG. 1, the tool spindle 26 is rotated by a rotary drive device 60 provided on the tool spindle stock 14. The rotary drive device 60 has a tool rotation servomotor 62 mounted on the frame 24. The tool rotation servomotor 62 is rotatable in both forward and reverse directions,
It is a motor capable of controlling the amount of rotation, and its rotation center line is attached parallel to the rotation center line of the tool spindle 26, and rotates a shaft 68 rotatably supported by the frame 24 via bearings 64 and 66. . The rotation of the shaft 68 is transmitted to the tool spindle 26 by the reduction gear train 70. The reduction gear train 70 is configured to transmit rotation while permitting axial movement of the tool spindle 26.

The tool spindle 26 is also moved along the rotation center line by a moving device 80 provided on the tool spindle stock 14. The moving device 80 includes a tool spindle 2 on the frame 24.
Servo motor 82 for tool movement mounted concentrically with 6
Have. The tool moving servomotor 82 is a motor capable of rotating in both forward and reverse directions and capable of controlling the amount of rotation, and rotates the ball screw 84. A nut 86 is screwed onto the ball screw 84, and a joint member 88 is fixed to the nut 86. The end of the tool spindle 26 is relatively rotatable and has a rotation center on the joint member 88 via a thrust bearing 90. They are connected so that they cannot move relative to each other in the line direction. Therefore, when the ball screw 84 is rotated by the tool moving servomotor 82, the nut 86 and the joint member 88 are moved and the tool spindle 26 is moved.
Are moved along the rotation center line. Ball screw 84
And the nut 86 constitutes a motion converting device.

This gear cutting machine has a control device 100 shown in FIG.
Controlled by. The control device 100 includes a CPU 10
2, a computer 110 having a ROM 104, a RAM 106, and a bus 108 connecting them is mainly used. An input port 112 and an output port 114 are connected to the bus 108, and the output port 114 is connected to the indexing motor 18, the tool rotation servomotor 62, and the tool movement servomotor 82 via drive circuits 116, 118, and 120. Although not shown in the figure, various devices necessary for gear cutting are connected. Also, the ROM 10
Various programs for performing gear cutting are stored in 4.

Next, the gear cutting will be described. First, rough machining is performed, and the front milling cutter 34 processes the tooth gap in the gear material 20 into an approximate shape. Therefore, the work material spindle 16 holds the gear material 20, and the front milling cutter 34 is attached to the tool spindle 26.
Processing is performed on the truncated frustoconical workpiece of the gear material 20. The front milling cutter 34 is rotated by the rotation driving device 60 and advanced by the moving device 80, and is cut into the gear material 20 to form one tooth groove.
When the formation of one tooth groove is completed, the front milling cutter 34 is retracted by the moving device 80, the gear material 20 is indexed, and the next tooth groove is formed. When all the tooth spaces are machined, as shown in FIG. 4, a rough-machined gear 136 having a shape of a spiral bevel gear having a plurality of teeth 130, tooth spaces 134, etc. is obtained.

In the processing of the tooth groove 134, as shown in FIG. 6, the forward movement distance of the front milling cutter 34 is linearly increased so as to cut into the gear material 20, and the forward movement is stopped at the position cut by a predetermined distance. And continue machining, then retract it to separate it from the gear material 20, and remove the front milling cutter 34.
Can be performed by rotating the gear material 20 by a certain angle in a state where the movement of No. 2 is stopped and rotating the portion to be processed next to the processing position.

Further, as shown in FIG. 7, it is also possible to increase the forward moving speed to increase the cutting depth at the beginning of the cutting of the front milling cutter 34 into the gear material 20 and to decrease the forward moving speed as the cutting progresses. . The control device 100 controls such adjustment of the forward speed of the front milling cutter 34, starting and stopping of the tool moving servomotor 82, and switching of the rotating direction. Computer 110
The ROM 104 stores a program for controlling the rotation amount of the tool moving servomotor 82 according to the mode of increase in the forward movement distance of the front milling cutter 34, and the tool moving servomotor 82 is controlled according to the program. It is.

Thus, by increasing the forward speed of the front milling cutter 34 at the beginning of cutting, it is possible to avoid the shortening of the life of the front milling cutter 34 and improve the machining efficiency. This is because the cutting resistance can be suppressed to an appropriate value even if the cutting depth is increased at the beginning of cutting when the length of the cutting edge of the front milling cutter 34 that is actually involved in cutting is short.

Roughing of the gear material 20 is completed,
After all the tooth spaces 134 have been machined, the machining tool is replaced with the disc broach 36 for finishing.
In this case, the rough processed gear 136 is a gear material. As shown in FIG. 8, processing is performed using a disc brooch 3
6 is rotated in the direction of arrow A shown in FIG.
The rough machining gear 136 is indexed in the indexing area W by reciprocating once in the direction of the rotation center line per piece, and the tooth groove 134 is processed into a tooth groove having a lead angle like a screw groove. It

For finishing, as shown in FIG. 11, the tool moving servomotor 82 is stopped and the disc broach 36 is moved.
Can be carried out only by rotating the disc broach 36 without moving along the rotation center line. However, if the tooth grooves of the two spiral bevel gears that mesh with each other are machined only by rotating the disc broach 36, FIG.
As indicated by the chain double-dashed line on the tooth flank 132, the tooth flanks 132 partially hit each other obliquely, and the load is concentrated, which shortens the life of the gear. On the other hand, if one or both of the tooth grooves of the two spiral tooth bevel gears are processed by moving the disc broach 36 as shown in FIG. 8, the tooth surface 132 contacts the entire surface at the time of meshing and the load is concentrated. Is not added, and the life of the gear is improved.

By controlling the amount of rotation of the tool moving servo motor 82 during machining, as shown in FIG. 9, the disc broach 36 is kept at a position advanced by a certain distance at the beginning of cutting, and then at a constant speed. It is possible to move forward and increase the forward speed near the end of the cut. In this way, as shown in FIG. 13, the relief portions 140 and 142 can be provided at the small diameter end and the large diameter end of the tooth 130, respectively, and when the gears are meshed, the tooth surfaces of the teeth that mesh with each other are provided. The load on the gear is not extremely concentrated on the small diameter end and the large diameter end, and the life of the gear can be improved.

Further, as shown in FIG. 10, the forward speed of the disc broach 36 can be accelerated.
In this way, the tooth surface 144 can be processed from a flat surface as shown in FIG. 14 to a curved surface as shown in FIG. This curved surface is a curved surface in which the tooth thickness near the small diameter end and the tooth near the large diameter end are respectively shaved off, and the tooth thickness is continuously reduced from the center of the tooth trace toward the end. is there. By doing so, it is possible to avoid the load from being concentrated on the small diameter end and the large diameter end of the teeth when the gears are meshed, and the life of the gear is improved.

In the above embodiment, it is possible to perform both rough machining and finishing machining by one gear cutting machine by exchanging machining tools.
Only one of them may be performed. Further, another processing may be performed.

Further, the control mode of the moving distance of the machining tool is not limited to the mode of the above embodiment, but may be variously set according to the shape and size of the tooth groove to be machined.

Further, the present invention can be applied to an apparatus for processing a gear other than a spiral tooth bevel gear, such as a spiral tooth hypoid gear.

In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a front sectional view schematically showing a tool headstock of a gear cutting machine according to an embodiment of the present invention.

FIG. 2 is a front view showing an appearance of the gear cutting machine.

FIG. 3 is a front view showing a disc broach used for finishing a tooth groove by the gear cutting machine.

FIG. 4 is a front view showing a part of a rough-machined gear whose tooth groove is roughly machined by the gear cutting machine.

FIG. 5 is a diagram conceptually showing a control device for controlling the gear cutting machine.

FIG. 6 is a time chart showing a rotation control of a tool rotation servo motor and a tool movement servo motor and a movement distance of a front milling cutter when rough machining is performed by the gear cutting machine.

FIG. 7 is a time chart showing another mode of the rotation control of the tool rotation servo motor and the tool movement servo motor and the movement distance of the front milling cutter during rough machining by the gear cutting machine.

FIG. 8 is a time chart showing rotation control of a tool rotation servo motor, a tool movement servo motor, and a movement distance of a disc broach during finishing processing by the gear cutting machine.

FIG. 9 is a time chart showing another mode of the moving distance of the disc broach during finishing by the gear cutting machine.

FIG. 10 is a time chart showing another mode of the moving distance of the disc broach at the time of finishing by the gear cutting machine.

FIG. 11 is a time chart showing rotation control of a tool rotation servo motor and a tool movement servo motor when machining is performed by the above gear cutting machine without moving a disc broach.

FIG. 12 is a diagram showing the contact of the tooth flanks when a gear having a tooth groove processed according to the time chart shown in FIG. 11 is meshed.

FIG. 13 is a perspective view showing a tooth having relief portions formed on a small end and a large end by finishing according to the time chart shown in FIG. 9.

FIG. 14 is a front cross-sectional view showing one of the tooth spaces finished by the above gear cutting machine.

FIG. 15 is a front cross-sectional view showing another aspect of the tooth groove that has been finished according to the time chart shown in FIG.

[Explanation of symbols]

 18 Indexing motor 20 Gear material 34 Front milling cutter 36 Disc broach 60 Rotation drive device 80 Moving device 82 Tool moving servo motor 84 Ball screw 86 Nut 100 Control device 134 Tooth groove 136 Roughing gear

Claims (1)

[Claims] 1. A machining tool capable of sequentially cutting each tooth groove of a gear material, a rotation driving device for rotating the machining tool, and a gear driving device for cutting the tooth material each time the tooth groove is completely cut. In a gear machining apparatus including an indexing device that rotates an angular interval between adjacent tooth spaces and a moving device that moves the machining tool along a rotation center line of the machining tool, the moving device controls the amount of rotation. A possible electric motor and a motion conversion device that converts the rotation of the electric motor into a movement along the rotation center line of the machining tool are included, and a control device that controls the rotation of the electric motor is provided. Characteristic gear processing device.