JPS6236828B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of machining the end face of a stepped portion adjacent to a cylindrical part of a workpiece using an angular grindstone, and more specifically, to a machining method in the case where the end face is wider than the grinding surface of the whetstone. .

When using an anguilla grindstone to grind a step end face that is wider than the grinding surface of the grindstone perpendicular to the workpiece axis, conventionally, as shown in Fig. 1, the grindstone G
The step end face is moved outward by repeating the cutting operation of cutting along the path 10 obliquely intersecting the workpiece axis Ow, and the position correction action of moving the end face side grinding surface Gb of the grindstone G in the direction away from the end face Wb. However, with this method, grinding resistance acts only on the grinding surface near the top P of the grindstone G each time a cutting operation is performed, so only the grinding surface near the top P of the grindstone G wears out. As a result, sagging occurs, making it difficult to machine the cylindrical portion Wa or step end face Wb of the workpiece W up to the corner R with high precision at right angles to the axis.

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 designed to enable machining of wide step end surfaces without applying grinding resistance to the top of the grindstone. The step is characterized in that the step is cut into the end face side, and then the grindstone is moved in a direction perpendicular to the workpiece axis and away from the workpiece to process the stepped end face.

Embodiments of the present invention will be described below with reference to the drawings. Figure 2 shows a schematic configuration of an anguilla grinding machine that processes the end face of a workpiece using the method according to the present invention.
A whetstone head 21 that carries an angular-shaped whetstone G having cubic boron nitride abrasive grains is slidably guided along guide surfaces 22 and 23 formed on the bed 20, and this whetstone head 21 A feed screw 26 is connected to a pulse motor 25 via a gear mechanism 24.
are screwed together.

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 is driven by a pulse motor 30. A feed screw 31 is screwed together. A headstock 32 and a tailstock 33 are placed on the work table 27,
A workpiece W having a cylindrical portion Wa and a stepped portion adjacent to the cylindrical portion is rotatably supported by the center of the headstock 32 and the tailstock 33. The axis Ow of this workpiece W 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 grindstone G, there is a first grinding surface Ga that is parallel to the workpiece axis Ow and narrower than the grinding width of the cylindrical portion Wa of the workpiece W, and a step end surface Wb of the workpiece W that is perpendicular to this.
A narrower second grinding surface Gb is formed,
The cylindrical portion Wa and the end surface Wb of the stepped portion of the workpiece W are ground by the first grinding surface Ga and the second grinding surface Gb. Since the path 38 of the grindstone G forms an acute angle θ 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 is in the radial direction of the workpiece W (X-axis direction) Therefore, it is necessary to convert the amount of movement in the radial direction.
Therefore, in this embodiment, in order to eliminate the need for converting the amount of radial movement, the gear ratio of the gear mechanism 24 is set to a predetermined value, so that the pulse motor 25 receives n pulses whose setting unit is Δd. As shown in FIG.
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 25.

Furthermore, an end surface position measuring head 40 is mounted on the bed 20 to send a signal representing the position of the reference end surface Ws to a position detection circuit 39 that detects that the workpiece W has been indexed to the reference position in the Y-axis direction. It is placed.

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 DS7 that set data necessary for machining the workpiece, and a pulse motor 2.
Drive units DU1 and DU that drive 5 and 30
2 are connected.

The CPU 41 executes a program stored in the internal memory to perform the necessary control for the grinding cycle shown in FIG. In this embodiment, the first traverse end (the rightward end of the work table) is used a specified number of times.
Then, the grindstone head 21 is sent so that the first grinding surface Ga moves by V, and the cylindrical part Wa is traverse-ground.
When the grinding of the cylindrical portion Wa is completed, the work table 27 is moved to the right to cut the second grinding surface Gb of the grinding wheel G into the end surface Wb of the workpiece W, and then the grinding wheel G is moved in a direction perpendicular to the workpiece axis Ow. The end face Wb is machined by retreating relative to the workpiece W.

In addition, in this embodiment, the position of the work table 27 where the workpiece W comes to the position shown by the solid line in FIG.
As the traverse end of the cylindrical portion Wa, the grindstone G is configured not to interfere with the step end face Wb during traverse grinding of the cylindrical portion Wa. For this reason, the CPU 41 operates on the reference plane of the workpiece W as shown by the two-dot chain line in FIG.
A function to index the work table 27 to a reference position where the intersection Q between the Ws plane and the workpiece axis Ow intersects with the travel path 38, and a function to index the work table 27 from this reference position.
It has a function of moving the work table 27 by L1+l-(D1/2tanθ) in the Y-axis direction and indexing the work table 27 to the first traverse end. In addition, L1 is the reference plane
Indicates the distance between Ws and the step end face Wb at the time of finishing,
l indicates a set clearance that is larger than the machining allowance Δl of the end face Wb by a predetermined amount, and D1 indicates the finished diameter of the cylindrical portion Wa.

Next, the specific operation of the CPU 41 will be explained based on the flowchart of FIG. Now, when an unillustrated start switch is pressed with the work table on which the workpiece W is attached to 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 positioned at the rapid forward end. After this, the CPU 41 goes to step 5.
At step 3, the traverse counter TC for counting the number of traverses is reset to zero, and then 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.

At step 59, a number of pulses corresponding to the set clearance amount l are distributed to the Y axis, and the work table 27 is further moved to the right by l from the first traverse end. As a result, the second grinding surface of the grindstone G
Gb is cut into the step end face Wb side by the grinding amount △l,
The inner periphery of the step end face Wb is ground. The moving speed of the work table 27 at this time is set to a speed that does not burn the second grinding surface Gb of the grindstone G.

When the cutting into the step end face Wb is completed in this way, the CPU 41 moves to step 60,
Control is performed to relatively move the grindstone G back by Vb in the direction orthogonal to the workpiece axis Ow. For this purpose, as shown in FIG.
Although it is necessary to move the work table 27 to the right by Vb/tanθ at the same time as moving the work table 27 backward by Vb/sinθ along the Then, the grinding wheel head 21 moves by Vb/sinθ along the travel path 38, so the CPU 41 distributes the number of pulses corresponding to Vb to the X axis and simultaneously distributes the number of pulses corresponding to Vb/tanθ to the Y axis. The grindstone G is then moved back in a direction perpendicular to the workpiece axis.

FIG. 8 shows a flowchart when the above pulse distribution is performed using the pulse distribution method disclosed in Japanese Patent Publication No. 52-6430.
71, X-axis movement amount Vb and Y-axis movement amount Vb/tanθ
After setting in the internal registers Xe and Ye, the cumulative register ΣR is cleared in step 72, and the process moves to step 73. At step 73, Ye is added to the register ΣR, and at step 74 it is determined whether the value after the addition exceeds Xe/2. If the value after addition does not exceed Xe/2, the pulse is distributed only to the
If the value exceeds ΣR, the pulses are distributed to both the X and Y axes in step 76, and then Xe is subtracted from the register ΣR in step 77, and the process proceeds to step 78. Step 78 is a step in which the completion of pulse distribution is determined based on the number of pulses distributed to the X axis. If it is determined that pulse distribution is complete, the process returns to the control routine shown in FIG. 6, and it is determined that pulse distribution is not completed. If it is determined that this is the case, the process returns to step 73 after a predetermined period of time has elapsed.

As a result, continuous pulses are distributed on the X-axis, pulses that are appropriately thinned out are distributed on the Y-axis, and the grinding wheel G is rotated so that the second grinding surface Gb is 1/1/2 from the finished surface position of the step end surface Wb. It is set back so that it does not deviate by more than 2 pulses. Thereby, the step end surface Wb is processed with high precision, and the vicinity of the top of the grindstone G is also prevented from sagging due to the processing of the step end surface Wb.

When the machining of the step end face Wb is completed, the grindstone head 21 is retreated at a rapid speed along the travel path 38 to the original position, completing the machining cycle.

FIG. 9 shows a grinding machine that can move a grinding wheel head 21 that supports an angular shaped grinding wheel G in a direction perpendicular to the workpiece axis Ow to create a cylindrical part Wa that is wider than the grinding surface of the grinding wheel G. The grinding system is shown for processing a workpiece W having an end surface Wb, and a grindstone head 21 is guided by guide surfaces 22' and 23' formed in a direction perpendicular to the workpiece axis Ow. If such a grinder is used, the end face of the stepped part can be
When processing Wb, there is no need to simultaneously distribute pulses on two axes; as shown in FIG. good. For this reason, the CPU 41' of this embodiment processes the step end face Wb by distributing a number of pulses corresponding to Vb only to the X axis.

In the above embodiment, the cylindrical portion Wa is processed by traverse grinding, but when the width of the cylindrical portion Wa is narrower than the first grinding surface of the grinding wheel G, and when the cylindrical portion Wa is plunge-ground, The present invention can be applied even when processing only the end face of a stepped portion.

As described above, in the present invention, the grinding surface perpendicular to the workpiece axis is cut into the step end face side at the inner part of the step end face, and then the grinding wheel is retreated in the direction perpendicular to the workpiece axis to create the step. Since the end face of the grinding wheel is machined, even when using an angular grindstone to process an end face that is wider than the grinding surface of the grinding wheel, large grinding resistance does not act on the area near the top of the grinding wheel. This can prevent sores from forming on the skin. For this reason, even when processing an end face wider than the grinding surface of the grindstone using the angular grindstone, 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 schematic plan view of a grinding machine showing the first embodiment of the present invention, with an electric circuit also shown, and 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 in FIG. 2, FIG. 4 is a diagram showing the relative movement of the grinding wheel G during the grinding cycle, and FIG. 6 is a flowchart showing the operation of the arithmetic processing unit 41 in FIG. 2, and FIG. 7 is a diagram showing the position of the grinding wheel G when moving it in a direction perpendicular to the workpiece axis. FIG. 8 is a flowchart showing the specific process of step 60 in FIG. 6. FIG. FIG. 10 is a diagram showing the relative movement of the grinding wheel G during the grinding cycle in FIG. 9. 21... Grindstone head, 25, 30... Pulse motor, 2
7... Work table, 32... Headstock, 33... Tailstock, 38... Path, 39... Position detection circuit, 40... End surface position detection head, 41... Arithmetic processing unit, 59...
Step of cutting the grindstone toward the step end face side, 60... Step of retracting the grindstone in the direction orthogonal to the workpiece axis, G... Grindstone, Ga... First grinding surface, Gb... Second grinding surface, W... Workpiece, Wa...cylindrical part, Wb...step end face.

Claims (1)

[Claims] 1. For machining a step end face that is wider than the second grinding surface adjacent to one end of a cylindrical part of a workpiece using an angular grindstone having a second grinding surface orthogonal to a first grinding surface parallel to the workpiece axis. The method includes the steps of: cutting the second grinding surface by a predetermined amount into the step end surface side at an inner portion of the step end surface, and then turning the grindstone perpendicularly to the workpiece axis so that the first grinding surface cuts into the cylindrical portion. A method for processing a workpiece using an angular grindstone, characterized in that the end face of the stepped portion is processed by a step of moving it in a direction away from the angular grindstone.