JP2001269816A - Gear machining method and gear machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a form error in a cutting edge portion of a cutting tool and bending moment on the cutting tool due to cutting resistance from influencing the accuracy of gear finishing. SOLUTION: A gear finishing method uses at last four-axis control to offer a relative cutting feed between a cutting tool and a gear workpiece so that the cutting tool scans a tooth flank of the gear workpiece with a minimal possible nonzero constant inclination to the normal to the tooth flank at each cutting point within a range with no interference between the cutting tool and the gear workpiece. A gear machining device comprises feed means 22, 26 and 30 on three orthogonal axes for a cutting tool T, rotating means 10 and 15 on two orthogonal axes for a gear workpiece, and control means 40 and 60 for effecting drive control on the cutting tool feed means and the gear workpiece rotating means so that the cutting tool scans a tooth flank of the gear workpiece with a minimal possible nonzero constant inclination to the normal to the tooth flank at each cutting point within a range with no interference between the cutting tool and the gear workpiece.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for processing a gear.

[0002]

2. Description of the Related Art In the prior art, gear finishing is performed by:
For example, it is performed by a gear grinding device as disclosed in Japanese Patent Application Laid-Open No. 9-108941 or a three-axis control end mill / milling machine (machining center) as shown in FIG. In a gear grinding apparatus, a tooth surface of a gear appropriately indexed around an index axis is appropriately fed with a grindstone having a shape corresponding to a tooth shape to finish the tooth surface.

In a three-axis control end mill / milling machine, a column 71 which advances and retreats in a Z-axis direction (horizontal direction in FIG. 8) and a column 72 which moves in an X-axis direction (vertical direction in FIG. 8) face each other on a bed 70. In the column 71, the bevel gear G is mounted on the index axis in the Z-axis direction so as to be indexed and rotated. In the column 72, the ball end mill M is oriented in the Z-axis direction so as to face the bevel gear G. Main shaft 73 of
Is mounted so as to move in the Y-axis direction (vertical direction in FIG. 8).

The columns 71, 72 and the spindle head 74
Are respectively driven by a servomotor, the indexing shaft is indexed and rotated by the servomotor, and the main shaft 73 is driven to rotate by a main shaft driving motor. The bevel gear G is appropriately indexed around the indexing axis, and the teeth to be machined are opposed to the ball end mill M that is being driven to rotate. And XY
The feed in each direction of the Z axis is performed by the columns 71 and 72 and the spindle head 74.
To cut the tooth surface of the bevel gear G, which is a three-dimensional curved surface whose direction changes with respect to the Z axis due to three-dimensional relative displacement between the tooth surface and the tip of the ball end mill M.

[0005]

Problems to be Solved by the Invention
In the case of a gear grinding apparatus as disclosed in Japanese Patent Publication No. 1 (1993), a grinding wheel suitable for the number and shape of the gear teeth is required, and the grinding wheel surface shape changes due to grinding wheel wear, and the gear processing accuracy is reduced. I do.

[0006] A three-axis control end mill as shown in FIG.
In the milling machine, the inclination angle α of the ball end mill M changes successively from the cutting point on the hemisphere at the tip of the ball end mill M and the normal to the tooth surface of the cutting point of the bevel gear G as shown in FIG.

However, since there is an error in the shape of the tip of the ball end mill, the shape error is transferred to the tooth shape, and the gear machining accuracy is reduced. The change in the inclination angle α of the ball end mill from the normal line to the tooth surface of the cutting portion changes the bending moment with respect to the ball end mill M due to the cutting resistance, that is, the deformation amount of the ball end mill M. give. The present invention solves the above-mentioned problems of the prior art in the finishing of gears, especially bevel gears.

[0008]

According to the present invention, there is provided a method for finishing a gear, in which an inclination angle of a tooth surface from a normal line at a cutting point is set to be as small as possible and not zero as long as a cutting tool does not interfere with a gear to be processed. While maintaining, for example, the cutting tool and the gear to be machined are scanned so that the tooth surface of the gear to be machined is scanned by the cutting tool while maintaining the minimum inclination angle when the tooth bottom of the gear to be machined is the cutting point. Is performed by at least four-axis control.

The machining apparatus for performing the gear finishing method according to the present invention includes, for example, feed means for a cutting tool having three orthogonal axes, rotation driving means for a gear to be machined around one axis or two orthogonal axes, and a cutting tool having a gear to be machined. Feed means of the cutting tool so that the tooth surface of the gear to be machined is scanned by the cutting tool while maintaining the inclination angle from the normal of the tooth surface at the cutting point at the cutting point as small as possible, not zero, within a range not interfering with There is provided control means for drivingly controlling the rotation drive means of the gear to be processed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A machining apparatus for carrying out a method for machining a master gear for checking bevel gear accuracy according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the left, right, up and down directions will be described as the left, right, up and down directions in FIG.

In FIG. 1, on the near side of the bed 1,
A table 2 on which a workpiece W is mounted is placed as described later, and a column having a spindle head as shown in FIG. 2 and having a spindle head as shown in FIG. (Vertically).

A first support 3 and a second support 4 are provided on the upper surface of both ends of the table 2 so as to face each other in the left-right direction. The first support 3 and the second support 4 are provided with rotary shafts 5 and 6 having a coaxial relationship with respect to a center axis O in the X-axis direction by bearings so as to be rotatable. A rotating disk 7 is formed at the protruding end of the shaft 5.

As shown in FIGS. 3 and 4, arms 8a extending upward are formed on both end faces in the longitudinal direction, and the tilt table 8 can be tilted around the O axis. That is, one arm 8a of the tilt table 8 is diametrically fixed to the rotating disk 7, the other arm 8a is fixed to the protruding end of the rotary shaft 6, and the tilt table 8 is In an eccentric position.

The first support 3 is provided with a servomotor 10 having an encoder 9, and the second support 4 is provided with a servomotor 11 which rotates synchronously with the servomotor 10.
The output shaft of the servomotor 10 is connected to the rotation shaft 5, and the output shaft of the servomotor 11 is connected to the rotation shaft 6. Then, the flange-shaped braking plate 12 concentrically fixed to the rotating disk 7 is released and fastened by the electromagnetic braking device 13 provided on the first support 3.

Accordingly, when the rotary shafts 5 and 6 are driven to rotate by an appropriate rotation angle by the servo motors 10 and 11, the tilting table 8 is tilted to an appropriate angle around the O axis, and the electromagnetic brake device 13 applies a brake plate. The tilting table 8 is maintained in a tilted state by the 12 being fastened. Then, the rotation angles of the servo motors 10 and 11, that is, the tilt angles of the tilt table 8, are detected by the encoders 9 and 10, and the detection signals are fed back to a numerical controller described later.

In this embodiment, since the workpiece W is a bevel gear or a bevel gear, the tilting table 8
Is used only when attaching / detaching the workpiece, but when the workpiece can be controlled by four axes such as straight teeth and helical spur gears, the tilting table is turned to the optimum angle for machining. After that, it may be fastened.

As shown in FIGS. 3 and 4, an indexing rotary table 16 that is indexed and rotated about a P-axis in the Y-axis direction by a servomotor 15 having an encoder 14 is provided in the center area on the tilting table 8. On the indexing rotary table 16, there is provided a pallet fixing device 18 for mounting and fixing a pallet 17 on which a workpiece W which is a bevel gear is mounted.

As shown in FIG. 2, a guide 20 provided in the X-axis direction on the back side of the bed 1 guides the X-axis direction by a screw mechanism driven by a servomotor 22 having an encoder 21. The saddle 23 is moved by the servo motor 26 having an encoder 25. The saddle 23 is guided by a guide 24 provided on the upper surface of the saddle 23 in a Z-axis direction orthogonal to the X-axis direction on a horizontal plane. Column 2 which is moved in the Z-axis direction by the set screw mechanism
7 is placed.

The front surface of the column 27 is guided by a guide 28 provided in the Y axis direction (vertical direction), and is moved in the Y axis direction by a screw mechanism driven by a servomotor 30 having an encoder 29. A spindle head 31 is provided. As shown in FIG. 4, the spindle head 31 is provided with a cutting tool T, which is a ball end mill projecting toward the workpiece W on the inclined table 8 in the Z-axis direction. It is mounted so as to be driven to rotate.

As shown in FIG. 5, the servo motors 10, 1
1 is through a drive circuit 41, the servo motor 15 is through a drive circuit 42, the servo motor 22 is through a drive circuit 43, the servo motor 26 is through a drive circuit 44, and the servo motor 30 is through a drive circuit 45. The encoders 9, 14, 21, 25, and 29 of the respective servo motors are respectively connected to the numerical controller 40 via a controller and driven based on a command from the numerical controller 40. The signal is connected so as to feed back the signal to the numerical controller 40.

The numerical controller 40 is connected to a sequence controller 50 so as to input and output each other, and the spindle motor 32 is controlled by a sequence controller 50 via a drive circuit 46 so as to be controlled and driven based on a command from the sequence controller 50. 50.

Further, separately from the numerical controller 40, a CPU
(Central processing unit) 61, RTC (clock signal generation circuit) 62, ROM 63, RAM 64, fixed disk 65
And a microcomputer 60 mainly composed of interfaces 66a, 66b, and 66c, and a numerical controller 40 and a sequence controller 50.
Are connected to the interfaces 66a and 66b so as to mutually input and output with the microcomputer 60, respectively. A keyboard 67 is connected to the microcomputer 60, and a CRT display device 68 is connected to the interface 66c so as to be input from the microcomputer 60.

A method of machining the master gear for checking the accuracy of the bevel gear will be described together with the operation and operation of the above-described grinding device. First,
Indexing rotary table 1 with pallet 17 on which workpiece W is mounted
6 is fastened by the pallet fastening device 18.

The workpiece W is a bevel gear accuracy checking master gear which is a spiral bevel gear. The finishing is performed for each tooth surface of each tooth. The spindle motor 32 is rotationally driven by a command from the sequence controller 50, and the tool spindle, ie, the cutting tool T, rotates.

The three-dimensional feed of the cutting tool T to the workpiece W and the workpiece W to the cutting tool T in the Z-axis direction are performed.
The following servo motors that perform the three-dimensional tilting described above are driven by the numerical control device 40.

The servo motors 10 and 11 are driven to rotate,
The inclination table 8 is tilted so that the tooth trace direction of the processing tooth surface at the cutting start point is in the upright direction, the servo motor 15 is driven to rotate, and the processing tooth surface to be finished is oriented in the Z-axis direction at a predetermined angle. The indexing rotary table 16 is indexed and positioned.

When the cutting tool T in the Z-axis direction cuts into the tooth space and scans the tooth surface as described later, the axis of the tooth is a three-dimensional curved surface as shown in FIG. It is maintained in a direction inclined by a predetermined inclination angle θ from a normal line h to the surface.

The inclination angle θ is determined by the cutting tool T during cutting feed.
Must be in a direction such that the tooth space does not interfere with the adjacent tooth surface between the processing tooth surface, and in such a condition range, the deformation amount of the cutting tool T due to the cutting resistance, that is, the cutting tool T In order to minimize the bending moment, the inclination angle is preferably as small as possible.

Since the inclination angle from the normal h is maintained at a predetermined angle, in the cutting tool T, a predetermined point deviated by a predetermined amount from a vertex of the tip of the hemisphere where cutting is not performed (in the center axis cross section). (Point) comes into contact with the cutting start point of the processing tooth surface, and the cutting point of the cutting tool T that affects the cutting of the tooth surface is maintained at that point. The greatest interference with the adjacent tooth surface during cutting feed occurs when the cutting tool T cuts the vicinity of the bottom of the tooth that has most entered the tooth space, and the minimum allowable inclination angle at that time is the predetermined angle.

Then, the servo motor 22 and the servo motor 30 are driven to rotate, and the cutting tool T rotated by the spindle motor 32, which is driven to rotate by a command from the sequence controller 50, faces the cutting start point of the processing tooth surface. , The saddle 23, that is, the column 27, moves in the X-axis direction, and the spindle head 31 moves in the Y-axis direction.

Then, the servo motor 26 is driven to rotate, and the column 27 is moved in the Z-axis direction so that the cutting tool T rotated by the spindle motor 32 is directed to the cutting start point on the processing tooth surface. Eventually, the cutting tool T is cut in a predetermined amount in the tooth surface at the cutting start point in a predetermined inclination direction.

Then, in order to give a three-dimensional feed to the cutting tool T so that the tip of the cutting tool T, which has been cut by a predetermined amount, scans the machining tooth surface, the tool-side feed servomotors 22, 26,.
29 is driven to rotate. As a result, the machining tooth surface is cut by the cutting tool T. However, since the machining tooth surface is a three-dimensional curved surface, the inclination angle of the tooth surface of the cutting position with respect to the cutting tool T held in the Z-axis direction is It changes sequentially with the movement of.

Therefore, the inclination angle θ of the cutting tool T with respect to the tooth surface at the cutting start point is maintained during cutting feed, that is, the inclination angle θ is maintained constant from the normal h to the tooth surface which is a three-dimensional curved surface. As described above, the servomotors 10 and 15 are driven to rotate, and the pallet 17, that is, the workpiece W is moved through the tilt table 8 and the indexing rotary table 16 in the X-axis direction.
P about the Y-axis direction that rotates around the axis and passes through the center
It rotates about an axis, that is, a central axis.

Thus, as shown in FIG. 7, the machined tooth surface which is a three-dimensional curved surface is cut only at a predetermined point (a point in the center axis cross section) which is deviated from the apex of the hemispherical tip of the cutting tool T by the predetermined amount. You.

Servo motors 22, 26, 30 so that the cutting tool T is cut and fed so as to scan the tooth surface of the bevel gear.
In addition to controlling the rotational drive of the
The rotational drive of the servomotors 10 and 15 so that the cutting tool T does not interfere with the teeth of the bevel gear as the workpiece W and maintains the inclination angle θ (not zero) from the normal h of the tooth surface as small as possible. Is controlled by the numerical controller 40, and control data for that is input from the microcomputer 60 to the numerical controller 40.

In the microcomputer 60, the dimensions and shape of the workpiece W and the dimensions and shape of the cutting tool T are inputted and stored in advance, and based on them, the three-dimensional position of the cutting tool T and the three-dimensional inclination of the workpiece W are determined. The calculated value is input to the numerical controller 40.

The above operation will be described with reference to the flowchart of FIG. CAD data, which is the dimension and shape data of the workpiece W (bevel gear) in CAD, is
The recorded data of the floppy (registered trademark) disk FD in which the CAD data is recorded directly from the AD or
The data is input to the microcomputer 60 via D. Alternatively, the recording data of the tape on which the dimension / shape data of the workpiece W (bevel gear) is recorded is input to the microcomputer 60 via the tape reader (STEP 1).

At this time, the processing conditions such as the size and shape of the cutting tool T, the number of revolutions of the spindle, the feed speed, and the pick feed are also input to the microcomputer 60 by the keyboard at the same time. Alternatively, the data is input to the microcomputer 60 via online, FDD, or a tape reader in the same manner as the size / shape data of the workpiece W (bevel gear). In the microcomputer 60, the inclination angle θ of the cutting tool T is calculated based on the data input as described above (STEP 2).

The inclination angle θ of the cutting tool T may be determined based on the operator's experience and may be manually input to the microcomputer 60 in addition to the calculation by the microcomputer 60. After inputting a tilt angle that does not cause interference, the machine is actually operated to check for interference, the tilt angle is gradually reduced while trial and error is repeated, and the minimum tilt angle θ is determined. The operation may be input to the microcomputer 60 (STEP 3).

In the microcomputer 60, NC data for five-axis control is created based on the machining conditions and the inclination angle θ of the cutting tool T. (STEP 4). The NC data created by the microcomputer 60 is input to the numerical controller, and the numerical controller 40 controls the servomotors 10, 15, 22, 2 based on the NC data.
The rotational drive of the control units 6 and 30 is controlled (STEP 5).

At the time of the interference check, the time-varying states of the workpiece W and the cutting tool T are input to the microcomputer 60 from the numerical controller 40, and the above-described calculations are sequentially performed. In the above embodiment, five-axis control of three axes on the cutting tool side and two axes on the workpiece side is performed and applied to bevel gears, bevel gears, and the like. In the case of a spur gear, four-axis control may be used.

[0042]

According to the gear finishing method of the present invention, the relative cutting feed between the cutting tool and the work gear is performed so that the tooth surface of the work gear is scanned by the cutting tool. As long as the cutting tool does not interfere with the gear to be processed, the inclination angle from the normal of the tooth surface at the cutting point is maintained at a constant value other than zero.

Accordingly, since the cutting point around the axis of the cutting tool is maintained at one point, the shape error of the cutting blade portion of the cutting tool is not transferred to the tooth shape, so that the gear machining accuracy is maintained. Moreover, since the inclination angle is as small as possible, the bending moment of the cutting tool due to the cutting resistance is small, that is, the deformation of the cutting tool which affects the gear machining accuracy does not occur.

[Brief description of the drawings]

FIG. 1 is a front view of a gear finishing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a column on a tool spindle side of the gear finishing device according to the embodiment of the present invention.

FIG. 3 is a front view of a workpiece-side configuration of the gear finishing device according to the embodiment of the present invention.

FIG. 4 is a plan view of a work-side configuration of the gear finishing device according to the embodiment of the present invention.

FIG. 5 is a configuration diagram of a control device of the gear finishing device in the embodiment of the present invention.

FIG. 6 is a flowchart of control of the gear finishing device in the embodiment of the present invention.

FIG. 7 is an operation explanatory view of an end mill for gear finishing in the embodiment of the present invention.

FIG. 8 is a side view of a gear finishing device according to the related art.

FIG. 9 is an operation explanatory view of an end mill for gear finishing in a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 bed 2 table 3 first support 4 second support 5,6 rotating shaft 7 rotating disk 8 tilting table 8a arm 9,14,21,25,29 encoder 10,11,15,22,26,30 Servo motor 12 Braking plate 13 Electromagnetic braking device 16 Indexing rotary table 17 Pallet 18 Pallet fastening device 20, 24, 28 Guide 23 Saddle 27 Column 31 Spindle head 32 Spindle motor 40 Numerical control device 41, 42, 43, 44, 45 , 46 drive circuit 50 sequence controller 60 microcomputer 61 CPU (central processing unit) 62 RTC (clock signal generation circuit) 63 ROM 64 RAM 65 fixed disk 66a, 66b, 66c interface 67 keyboard 68 CRT display device W Workpiece (bevel gear) ) T cutting tool

Claims (4)

[Claims] 1. The tooth surface of a gear to be machined by a cutting tool while maintaining the inclination angle from the normal of the tooth surface at the cutting point as small as possible, not zero, as long as the cutting tool does not interfere with the gear to be machined. A gear machining method for performing relative cutting feed between a cutting tool and a gear to be machined so as to be scanned. 2. The cutting tool according to claim 1, wherein the inclination angle of the cutting tool from the normal of the tooth surface of the gear to be processed at the cutting point is the minimum inclination angle when the root of the gear to be processed is at the cutting point. The described gear processing method. 3. The gear machining method according to claim 1, wherein relative cutting feed between the cutting tool and the work gear is performed by at least four-axis control. 4. A method for feeding a cutting tool having three orthogonal axes, a rotating means for rotating a gear to be machined about one axis or two axes, and a method of forming a tooth surface at a cutting point within a range where the cutting tool does not interfere with the gear to be machined. Control means for driving and controlling the feed means of the cutting tool and the rotation drive means of the work gear so that the tooth surface of the work gear is scanned by the cutting tool while keeping the inclination angle from the line as small as possible and not zero. Gear processing device equipped with