JPS6236829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for machining an end face of a stepped portion wider than the grinding surface of the grinding wheel in an angular grinding machine in which the angular grinding wheel is moved forward and backward along a path obliquely intersecting the axis of the workpiece. .

When grinding a stepped end face that is wider than the grinding surface of the grinding wheel perpendicular to the workpiece axis using an anguilla grinding machine, conventionally, as shown in Fig. 1, the grinding wheel G
A cutting operation that cuts along a path 10 that intersects obliquely with the workpiece axis, and an end face side grinding surface Gb of the grindstone G is cut into an end face Wb.
In this method, the step end face is ground stepwise from the outside by repeating a position correction operation in which the grinding wheel is moved away from As grinding resistance acts, the grinding surface near the top P of the grinding wheel G wears and sag occurs, and the cylindrical part Wa or step end face Wb of the workpiece W is cut perpendicularly to the axis with high precision up to the corner R. There was a drawback that it was difficult to process.

In particular, with expensive grinding wheels that use abrasive grains such as cubic boron nitride, the grinding surface Gb on the end face side, where the amount of grinding is small, is made quite narrow in order to increase the usage efficiency of the grinding wheel. This unavoidable occurrence of cracking caused a drop in machining accuracy.

In view of these problems, the present invention is capable of machining a wide stepped end face without applying grinding resistance to the top of the grinding wheel, and by moving the table, the stepped end face of the workpiece can be machined by the grinding wheel. The process of cutting into the end-side grinding surface and the retreat of the grinding wheel in the direction of travel oblique to the workpiece axis move the end-side grinding surface away from the stepped end surface and shift the position of the end-side grinding surface in the radial direction of the workpiece to the outside. The process is repeated, and the step end face is ground stepwise from the inner circumference.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 21 denotes a whetstone head that supports an angular grindstone G whose abrasive grains are cubic boron nitride.
23 and is slidably guided along the feed screw 24
and a pulse motor 26 via a gear mechanism 25.

On the other hand, the work table 27 is slidably guided in the Y-axis direction along guide surfaces 28 and 29 formed on the front surface of the bed 20, and the work table 27 is connected to a pulse motor 3 via a feed screw 30.
1. A headstock 32 and a tailstock 33 are placed on the work table 27, and the center of the headstock 32 and tailstock 33 has a wide cylindrical portion Wa and a stepped portion adjacent to this cylindrical portion. A workpiece W is rotatably supported. This workpiece W
The axis Ow is parallel to the guide surface of the work table 27 and forms an acute angle θ with the path 38 of the grindstone G.

On the outer peripheral surface of the grinding wheel G, there is a first grinding surface that is parallel to the workpiece axis Ow and narrower than the grinding width of the cylindrical part of the workpiece W.
Ga, and a second ground surface Gb that is perpendicular to this and narrower than the stepped portion of the workpiece W is formed, and these ground surfaces form a cylindrical portion Wa of the workpiece W and the end surface of the stepped portion.
Wb is ground. Since the path 38 of the grindstone G forms an acute angle θ8 with the workpiece axis Ow, when the grindstone G is moved by a predetermined amount L in the direction of the path 38, the first grinding surface Ga moves Lsinθ in the radial direction of the workpiece W. Therefore, it is necessary to convert the amount of radial movement.
Therefore, in this embodiment, by setting the gear ratio of the gear mechanism 25 to a predetermined value in order to eliminate the need for converting the amount of radial movement, the pulse motor 26 receives n pulses whose set unit is Δd. When distributed, the grindstone G moves along the travel path 38 (n×
Move by △d)/sinθ, and the first grinding surface of the grinding wheel G
Ga moves by a distance n×Δd equal to the number of pulses given to the pulse motor 26.

Furthermore, a work table 2 is placed on the bed 20.
An end face position measuring head 40 is placed to send a signal representing the position of the reference end face Ws to a position detection circuit 39 which detects that the reference end face Ws is indexed to the reference position in the Y-axis direction.

Next, a control device for machining a workpiece using the angular grinder having the above configuration will be explained.

41 is an arithmetic processing unit (hereinafter referred to as CPU) consisting of a microcomputer, etc., and this CPU 41 has a plurality of digital switches DS0 to DS8 that set data necessary for machining the workpiece, and a pulse motor 2.
Drive units DU1 and DU that drive 6 and 31
2 are connected.

The CPU 41 performs necessary control for the grinding cycle shown in FIG. 4 based on a program stored in the internal memory. In this embodiment, at the first traverse end (the rightward end of the work table 27) a specified number of times,
Grinding wheel head 2 so that the first grinding surface Ga moves by V
1 is sent to traverse grind the cylindrical part Wa, and when the grinding of the cylindrical part Wa is completed, the work table 2
The first grinding surface Gb of the step end surface Wb due to the rightward movement of step 7
The step end face Wb is machined by repeating cutting into and retreating along the travel path 38 direction of the grindstone G.

In addition, in this embodiment, the position where the workpiece W is positioned as shown by the solid line in FIG. I have to. Therefore, the CPU 41 has a function of indexing the work table 27 to a reference position where the intersection point Q of the reference plane Ws of the workpiece W and the workpiece axis Ow intersects with the path 38, as shown by the two-dot chain line in FIG. and move the work table 27 from this reference position to L1+l-
It has a function of moving in the Y-axis direction by (D1/2tanθ) and indexing the work table 27 to the first traverse end. In addition, L1 indicates the distance between the reference surface Ws and the step end surface Wb during finishing, and l is the distance between the end surface Ws and the step end surface Wb.
It shows a set clearance that is larger than the machining allowance Δl of Wb by a predetermined amount, and D1 shows the finished diameter of the cylindrical part Wa.

Next, the specific operation of the CPU 41 will be explained based on the flowchart of FIG. Now, when the unillustrated start switch is pressed with the work table on which the workpiece W is mounted at the position shown in Fig. 2,
In step 50, the CPU 41 detects the position detection circuit 39.
The work table 27 is indexed to the reference position by sending out pulses to the Y-axis from then until the positioning completion signal PES is sent out. After this, the CPU 41 goes to step 5.
1, calculate L1+l-(D1/2tanθ), distribute the corresponding number of pulses to the Y axis, move the work table 27 to the left, and index the work table 27 to the first traverse end. .

When the work table 27 is indexed to the first traverse end, the CPU 41 moves to step 52,
The number of pulses corresponding to the amount of movement Vo of the first grinding surface Ga during rapid traverse set in the digital switch DS3 is distributed to the X axis at a rapid traverse speed. As a result, the grindstone G is advanced by Vo/sin θ along the travel path 38, and the first grinding surface Ga is moved to the rapid forward end. After this, the CPU 41 goes to step 53.
After resetting the traverse counter TC, which counts the number of traverses, to zero, the process moves to step 54.

From step 54 to step 58, the cylindrical part
This is for traverse grinding Wa, and after distributing the pulse to the X axis to cut the first machined surface Ga by V in step 55, the work table 27 is adjusted according to the traverse amount Lt in steps 56 and 57. The pulse for reciprocating is distributed to the Y axis, and when the distribution is completed, the traverse counter is
The TC is incremented and the process returns to step 54. As a result, the cylindrical portion Wa is traverse-ground the specified number of times, and when the grinding is completed, the process moves from step 54 to step 59.

Steps 59 to 64 are a routine in which the step end face Wb is machined by alternately repeating the rightward movement of the work table 27 and the backward movement of the grindstone G.
In this embodiment, as shown in FIG.
The grindstone G is moved back to a position away from the finished surface Wb' of Wb, thereby shifting the position of the second grinding surface Gb in the workpiece radial direction. For this purpose, it is necessary to move the grinding wheel G backward by l/cosθ along the travel path 38. However, in this embodiment, the position of the grinding wheel G is controlled by the amount of movement of the first grinding surface Ga in the workpiece radial direction. Since the mechanism 25 is provided, the CPU 41
distributes the number of pulses corresponding to l×tanθ to the X axis to move the grindstone G backward.

Step 62 distributes the number of pulses corresponding to the set clearance l to the Y axis and moves the pulses to the work table 27.
This step moves the workpiece W to the right.
The step end face Wb is cut into the second grinding surface Gb of the grindstone G by the machining allowance Δl. Also, step 63 is
In this step, a number of pulses corresponding to xtanθ are distributed along the X axis, thereby causing the grinding wheel G to retreat along the path by l/cosθ. By repeating such operations, the step end face Wb is ground step by step from the inner circumference.

In this embodiment, the grinding width of the end face Wb due to the rightward movement of the work table 27 is accumulated to detect whether or not all of the step end face Wb has been ground, thereby completing the end face grinding. There is. That is,
In step 59, the width data of the second grinding surface Ga set in the digital switch DS7 is changed from Lg to Lg-.
Calculate l×tanθ and preset it in the calculation register ΣVb in step 60. After this, every time the work table 27 moves to the right and the grindstone G moves backward, l×tanθ is calculated from the preset value in step 64.
Reduce tanθ. As a result, when the grinding of the end face Wb is completed, the value of the register ΣVb exceeds the value of the step end face width Le set in the digital switch DS8, so in step 61, the value of the register ΣVb exceeds the value of the step end face width Le. determine whether the
If it has exceeded it, the process moves to step 65 and the grindstone G is retreated along the path 38.

As a result, the cylindrical part Wa and the step end face of the workpiece W are
The machining of Wb is completed, but in machining the step end face Wb, grinding resistance does not act on the grinding surface near the top of the grinding wheel G, and the grinding resistance is applied to the entire grinding surface Gb or to the opposite side of the top of the grinding surface Gb. Since the grinding resistance acts only on the edge of the grinding wheel, it is possible to prevent the vicinity of the top P of the grindstone G from sagging, and subsequent workpiece processing can be performed with high precision.

In addition, in the above embodiment, the radial position of the second grinding surface Gb moves by a tangent of the set clearance l due to one retraction operation of the grinding wheel. If the machining allowance of the end face Wb is large and the set clearance amount cannot be reduced, the stepped end face may not be able to be machined continuously. The amount of radial movement of the second grinding surface Ga per cycle may be within the width of the second grinding surface. Similarly, when the width of the second grinding surface of the grinding wheel G is wider than the end face machining allowance, the amount of radial movement of the second grinding surface Ga per cycle does not exceed the width of the second grinding surface. The width of grinding per time may be increased by increasing the amount of retreat of G. In these cases, it is necessary to change the amount of rightward movement of the work table 27 from the second time onwards in accordance with the amount of retreat of the grindstone G to keep the depth of cut constant.

Further, in the above embodiment, the cylindrical portion Wa was processed by traverse grinding, but when the width of the cylindrical portion Wa is narrower than the first grinding surface of the grindstone G and the cylindrical portion Wa is plunge-grounded, The present invention can be applied even when processing only.

As described above, if the step end face of a workpiece is processed using the processing method of the present invention, even when processing a step end face that is wider than the grinding surface of the grinding wheel using an angular grinder, the area near the top of the grinding wheel can be Grinding resistance does not act only on the grinding surface, and it is possible to prevent droop from forming on the top of the grindstone. Therefore, even when processing an end face wider than the grinding surface with the angular grinder, there is an advantage that the cylindrical portion or the end face can be processed with high precision up to the corner.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the locus of movement of the grinding wheel in the conventional end face grinding method, Fig. 2 is a plan view of a grinding machine showing an embodiment of the present invention with an electric circuit shown, and Fig. 3 is the same as that in Fig. A diagram showing the relationship between the depth of cut of the grinding wheel G and the amount of movement of the grinding surface, FIG. 4 is a diagram showing the movement locus of the grinding wheel G during the grinding cycle, and FIG. 5 is the first traverse of the workpiece W in FIG. 2. 6 is a flowchart showing the operation of the arithmetic processing unit 41 in FIG. 2, and FIG. 7 is a diagram showing the amount of retreat of the grindstone G during end face grinding. 21... Grindstone head, 26, 31... Pulse motor, 2
7... Work table, 32... Headstock, 33... Tailstock, 38... Path, 39... Position detection circuit, 40... End face position measuring head, 41... Arithmetic processing unit, 62...
Step 63 of cutting the step end face into the grinding surface of the whetstone, 63...
Step for retracting the grindstone, G... grindstone, Ga... first grinding surface, Gb... second grinding surface, W... workpiece, Wa...
Cylindrical part, Wb...Step part end face.

Claims (1)

[Claims] 1. An angular grinding machine in which an angular grinding wheel having a grinding surface perpendicular to the workpiece axis is advanced and retreated along a path oblique to the workpiece axis, is used to grind a grinding wheel that is wider than the grinding surface adjacent to one end of the cylindrical part. A method for machining an end face of a stepped part, wherein the workpiece is moved in an axial direction by moving a table on which the workpiece is placed, and the end face of the stepped part of the workpiece is cut by a predetermined amount on the grinding surface of the grindstone. repeating the step of retracting the grindstone along the path to move the grinding surface away from the step end face and shifting the position of the grinding surface in the workpiece radial direction to the outside within the width of the grinding surface; A workpiece processing method using an anguilla grinding machine, characterized in that the step end face is ground stepwise from the inner circumference.