JPS62241656A - Hone expansion method for honing and device thereof - Google Patents

Abstract

PURPOSE:To aim at preventing generation of heat due to hone loading, deformation in a workpiece and surface roughness failure from occurring, by altering the extent of expansion force in a way of controlling an expansion motor according to a state of turning torque of a spindle motor. CONSTITUTION:When high-pressure expansive cutting is carried out by rotation of the preset expansion motor 9, turning torque of a spindle motor 19 is within the range of preset high-pressure expansive cutting torque. When a cutting state gets out of order due to hone loading or the like and torque exceeds the range, the expansion motor 9 is reversely rotated by a control circuit inclusive of a torque meter 18 and a microcomputer 20 whereby spindle feed is suspended as long as the specified time. Next, rotational frequency of the expansion motor 9 is altered to the lower value than the last time, expansion is resumed, and the high-pressure expansion cutting is over, shifting to medium expansion cutting. in this connection, medium pressure and low pressure expansive cutting operations also are controlled likewise. Therefore, in either case when it exceeds the preset torque range or when it goes gown from it, the torque is detected during operation and compensation for expansion force is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to bore honing, and more particularly to a honing wheel expansion method and apparatus.

(Prior art) Conventionally, the grinding wheel expansion method used in bore honing processing involves machining using a preset expansion force, such as high-pressure expansion for the purpose of dressing the grinding wheel, medium-pressure expansion during cutting, and low-pressure expansion during dwell. It is something that does. In other words, a whetstone;
Machining is performed using a grindstone surface pressure determined by conditions determined by the workpiece, etc.

(Problem to be solved by the invention) However, since the self-sharpening action of the grindstone is not constant, good cutting conditions may not be obtained with the expansion force set to a constant value in the conventional method. Problems may occur such as heat generation due to clogging, distortion of the workpiece, or poor surface roughness due to excessive cutting of the grindstone.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention aims to provide a grindstone expansion method and an apparatus therefor that can control the grindstone expansion force according to the torque state during honing.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides (1) a grinding wheel that is inserted into a joint of a two-part grindstone held in a horn head holder, and is moved in an axial direction. A wedge-shaped horn that expands and contracts the outer end surfaces of the
The head is movably inserted into a hollow part of the main shaft which is connected to the horn head holding part at one end, and the lower end is slidably fitted to the outer periphery of the main shaft and a push rod which is in contact with the horn head. a feed member connected to the push rod through a longitudinal elongated hole on the side of the main shaft and a coupling member; and an expansion motor that moves the push rod forward and backward through a feed screw attached to the feed member. In a grindstone expansion device for honing processing, when cutting is being performed under a grindstone expansion force corresponding to a preset rotation speed N of the expansion motor, the rotational torque of the spindle motor that drives the spindle is If the cutting torque exceeds a preset cutting torque range and this abnormal state exceeds a certain period of time, a control circuit including a torque meter and a microcomputer reversely rotates the extension motor to control the feed of the push rod. A grindstone expansion method characterized by stopping the expansion for a certain period of time, and then changing the rotation speed of the expansion motor from N to N-= (correction value based on the amount of deviation of the cutting torque) when restarting the expansion. In order to carry out this method, (2) a microcomputer is installed that calculates the torque of a torque meter attached to the main shaft motor that drives the main shaft and inputs a control signal to the expansion motor. This is a grinding wheel expansion device.

(Example) The present invention will be described below based on drawings showing examples. FIG. 1 shows a vertical view of the device according to the invention. W is a cylindrical workpiece, and its bore surface is honed by an inserted grindstone 1.

The grindstone 1 consists of two parts, and the wedge-shaped head of the horn head 2 is inserted into the square-shaped mating surface.

The whetstone 1 and the horn head 2 are held in a horn head holder 3 which has openings on both sides through which both end faces of the whetstone 10 protrude. The upper part of the horn head holding part 3 is connected to a universal joint part 4a provided at the lower end of the main shaft 4.
The bins are combined.

The main shaft 4 is hollow from the lower end of the universal joint part 4a to the middle of the main shaft 4. The rod part 3a of the horn head 3 is slidably inserted into the lower part of the hollow part, and the rod part 3a of the horn head 3 is slidably inserted into the lower part of the hollow part. A push rod 5 is also slidably inserted in contact with the rod portion 3a. A pin 6 that is inserted laterally is attached to the upper end of the push rod 5, and both ends of the pin 6 protrude outside from a hole 4b provided in the main shaft 4 and are slidably fitted to the outer periphery of the main shaft 4. It is engaged with an annular groove of the sending member 7 via a bearing 6a. hole 4b
is an elongated hole parallel to the axis of the main shaft 4, and the push rod 5
is movable together with the feed member 7 relative to the main shaft 4. A feed screw 8 is attached to the feed member 7,
The feed screw 8 is rotated by an expansion motor 9.

The main shaft 4 is slidably inserted into a guide 10 whose upper part is cylindrical than the feed member 7, and the guide 10 has bushings 11.12.
is rotatably held by the A cylinder 13 is connected to the upper end of the main shaft 4 to move the main shaft 4 up and down.

The guide 10 and the main shaft 4 are connected via a key 14, and a sprocket 15 is attached to the outer periphery of the guide 10. The sprocket 15 is connected to a sprocket 17 by a chain 16, and the sprocket 17 has a torque
A meter 18 and a main shaft motor 19 are connected. The torque of the torque meter 18 is calculated by the microcomputer 20 and input to the expansion motor 9.

A method for expanding a grindstone using the grindstone expansion device configured as described above will be described. In FIG. 2, when high-pressure extended cutting is being performed at a preset rotation speed N1 of the extended motor 9, the rotational torque of the main shaft motor 19 is within a preset high-pressure extended cutting torque range Ta. During this process, if the cutting condition becomes abnormal due to clogging of the grindstone, the torque will exceed the Ta range. If this abnormal condition exceeds 1 second, the expansion motor 9 is rotated in the reverse direction and feeding is stopped for ta seconds. Next, when the expansion is restarted, the expansion motor rotation speed is changed to a value N'=N1-T1xα, which is lower than N, and the expansion is performed. Here, T1 is a value exceeding the range Ta, and α is a coefficient.

High pressure expansion cutting is completed, and then medium pressure expansion cutting is started. In this case as well, the intermediate pressure expansion cutting torque range Tb is set in advance and expanded at the expansion motor rotation speed N2. In this process, if the cutting state of the grindstone becomes abnormal due to excessive cutting of the grindstone, the torque will drop below the Tb range. When this state exceeds t seconds, the expansion motor 9 is reversely rotated to stop feeding for ta seconds.

These t and ta seconds are preset values as in the case of high-pressure expansion. When restarting the expansion, the expansion motor rotation speed is changed to a value higher than N2, N2-=N20T2×β, and the expansion is performed. Here, T2 is a value outside the range Tb, and β is a coefficient.

Medium pressure expansion cutting is completed, and then low pressure expansion cutting is started. In this case as well, the cutting torque is controlled in the same way as in high pressure and medium pressure cutting.

As described above, when the torque exceeds or falls below the set torque range, the torque is detected during all machining and the expansion force is corrected. The microcomputer 20 performs these calculations N'=N
1-T1Xα, N2-=N+T2Xβ, and has a function of instructing the expansion motor 9 of the corrected value.

For example, if the cutting torque increases due to clogging of the grindstone, expansion is temporarily stopped, and when restarting cutting, the expansion force is lowered. At this time, by pausing expansion, clogging of the grinding wheel is eliminated, and by lowering the expansion force, an increase in cutting torque is prevented, cutting is performed without applying extra force to the workpiece, and machining distortion can be prevented. can. Further, when the cutting torque decreases, increasing the expansion force prevents the decrease in the cutting torque and prevents surface roughness defects.

(Effects of the Invention) As explained above, the present invention provides a grinding wheel expanding method and a grinding wheel expanding device that can control the grinding wheel expanding force according to the torque state during honing, so that heat generation due to clogging of the grinding wheel and workpiece It is possible to prevent distortion of the grinding wheel or poor surface roughness due to excessive cutting of the grindstone, thereby stabilizing the machining time. In particular, highly accurate honed surfaces can be obtained even for thin-walled, low-rigidity workpieces.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view of a grindstone expansion device according to the invention, and FIG. 2 is an explanatory diagram of a grindstone expansion method. 1-... Grinding wheel 2... Horn head 3... Horn head holding part 4... Main shaft 5... Push rod door... Feed member 8... Feed screw 9... Expansion motor 18...Torque meter 19...Spindle motor 20...Microcomputer Applicant Toyota Motor Corporation agent Patent attorney Hidehiko Okada Drawings 1 Drawing 1

Claims (2)

[Claims] (1) A wedge-shaped horn that is inserted into the joint of a two-part whetstone held by the horn head holder, and expands and contracts the outer end surfaces of the whetstone laterally by moving in the axial direction.
The push rod is slidably inserted into a hollow part of the main shaft that connects the head and the horn head holder at one end, and the lower end is slidably fitted to the outer periphery of the main shaft and the push rod is in contact with the horn head. a feed member connected to the push rod through a longitudinal elongated hole on the side of the main shaft and a coupling member; and an expansion motor that moves the push rod forward and backward through a feed screw attached to the feed member. In a grindstone expansion device for honing processing, when cutting is being performed under a grindstone expansion force corresponding to a preset rotation speed N of the expansion motor, the rotational torque of the spindle motor that drives the spindle is If the cutting torque exceeds a preset cutting torque range and this abnormal state exceeds a certain period of time, a control circuit including a torque meter and a microcomputer reversely rotates the extension motor to control the feed of the push rod. When stopping the expansion for a certain period of time and then restarting it, the rotation speed of the expansion motor should be changed from N′=(N±
A grindstone expansion method characterized in that the grindstone is expanded by changing to a correction value (based on the amount of deviation of cutting torque). (2) A wedge-shaped horn that is inserted into the joint of the two-part whetstone held by the horn head holder, and expands and contracts the outer end surfaces of the whetstone laterally by moving in the axial direction.
The push rod is slidably inserted into a hollow part of the main shaft that connects the head and the horn head holder at one end, and the lower end is slidably fitted to the outer periphery of the main shaft and the push rod is in contact with the horn head. a feed member connected to the push rod through a longitudinal elongated hole on the side of the main shaft and a coupling member; and an expansion motor that moves the push rod forward and backward through a feed screw attached to the feed member. A grinding wheel expansion device for honing processing, comprising: a microcomputer that calculates the torque of a torque meter attached to a spindle motor that drives the spindle and inputs a control signal to the expansion motor; Features a grinding wheel expansion device.