JP6408512B2 - Centerless grinding machine and control method thereof - Google Patents

Description

  The present invention relates to a technique for grinding a workpiece while supporting the workpiece in a rotatable manner by contact with three members of a grinding wheel, an adjustment wheel and a blade without supporting the center.

  The present applicant has proposed a centerless grinding method in which a workpiece (workpiece) to be processed is changed, and an adjusting wheel base or a grinding wheel base can be automatically positioned according to a change in its diameter (for example, , See Patent Document 1).

Japanese Patent No. 50579947

  However, it is not preferable from the viewpoint of safety that the operator manually moves the grinding wheel and the slide on which the grinding wheel is mounted. For example, in an initial stage in which the positional relationship between the grinding wheel, blade and adjusting wheel, and hence the contact state of the grinding wheel, blade and adjusting wheel with respect to each workpiece is not properly adjusted, the operator manually removes the grinding wheel. While rotating around the axis, the slide on which the grinding wheel is mounted is advanced with respect to the work placed on the blade, and the grinding wheel and the work are brought into contact with each other to visually recognize the grinding point. Then, the operator retracts the slide by a certain amount from the contact state, and determines the original position of the slide.

  In addition, when a workpiece is cut in the radial direction with a grinding wheel or an adjustment grindstone, an air cut region is usually set at a low speed from the viewpoint of safety, but the production efficiency is reduced accordingly.

  Therefore, the present invention has an object to provide a centerless grinding machine capable of automatically adjusting the positional relationship between a grinding wheel, a blade and an adjusting wheel with high accuracy and a control method thereof from the viewpoint of ensuring safety of work and improving production efficiency. And

  The present invention includes a columnar grinding wheel, a columnar adjustment wheel, a blade disposed between the grinding wheel and the adjustment wheel, and a first actuator that adjusts an interval between the adjustment wheel and the blade. A second actuator that adjusts the distance between the grinding wheel and the adjusting wheel without changing the distance between the adjusting wheel and the blade, and a control that controls the operation of each of the first actuator and the second actuator. And a control method for the centerless grinding machine.

  The centerless grinding machine of the present invention further includes an external force sensor that outputs a signal corresponding to an external force acting on the blade, and the control device adjusts a distance between the adjusting grindstone and the blade to adjust the blade. The operation of the first actuator is controlled so that the workpiece is supported between the inclined surface which is the upper surface and the outer peripheral surface of the adjusting grindstone, and between the inclined surface which is the upper surface of the blade and the outer peripheral surface of the adjusting grindstone. The operation of the second actuator is controlled so that the distance between the grinding wheel and the adjusting wheel is narrowed from the state where the workpiece is supported, and the distance between the grinding wheel and the adjusting wheel is narrowed. It is determined whether or not the output of the external force sensor has decreased in the course of the process, and the change in the interval between the grinding wheel and the adjustment wheel is a requirement that the determination result is positive. And controlling the operation of the second actuator so as to vary the like.

  In the centerless grinding machine of the present invention, the control device may be configured to stop after the interval between the grinding wheel and the adjustment wheel is increased to a predetermined value on the condition that the determination result is affirmative. It is preferable to control the operation of the two actuators and to store and hold the stop position as the original position of the grinding wheel.

  In the centerless grinding machine of the present invention, the control device controls the operation of the second actuator so that the approaching speed between the grinding wheel and the adjusting wheel is reduced on the condition that the determination result is affirmative. It is preferable to do.

  In the centerless grinding machine of the present invention, in the state where the work is supported between the inclined surface which is the upper surface of the blade and the outer peripheral surface of the adjusting grindstone, the work force is applied to the work so that the output of the external force sensor increases. It is preferable to further include an external force action mechanism for applying an external force.

  The control method of the present invention is a control method for a centerless grinding machine comprising a cylindrical grinding wheel, a cylindrical adjusting wheel, and a blade disposed between the grinding wheel and the adjusting wheel. A step of supporting a workpiece between the inclined surface that is the upper surface of the blade and the outer peripheral surface of the adjusting wheel by adjusting the distance between the adjusting grindstone and the blade; and the inclined surface that is the upper surface of the blade; From the state in which the workpiece is supported between the outer peripheral surface of the adjustment grindstone, the step of narrowing the interval between the grinding grindstone and the adjustment grindstone without changing the distance between the adjustment grindstone and the blade; The step of measuring the external force acting on the blade in the process of narrowing the interval between the grinding wheel and the adjusting wheel, the step of determining whether the external force has decreased, and the determination result are positive As a requirement the door, characterized in that it contains a step of changing a variant of the distance between the grinding wheel and the regulating wheel.

  According to the centerless grinding machine and the control method thereof of the present invention, the operation of the actuator is controlled according to the change mode of the external force (or the output signal of the external force sensor) acting on the blade while the workpiece is in contact with the blade. The The positional relationship among the grinding wheel, the blade and the adjusting wheel can be automatically adjusted with high accuracy in view of the fact that the external force acting on the blade changes depending on the contact state of the workpiece with the grinding wheel or the grinding wheel and the adjusting wheel. . Thereby, the safety of work can be ensured without the operator touching the tool. Further, when the workpiece is cut in the radial direction by the grinding wheel or the adjustment wheel, at least a part of the air cut region can be omitted, so that the production efficiency of products from the workpiece can be improved.

The structure explanatory view of the centerless grinding machine as one embodiment of the present invention. Explanatory drawing regarding the control method of the centerless grinding machine as one Embodiment of this invention. Explanatory drawing regarding the time change aspect of the external force which acts on a braid | blade.

(Configuration of centerless grinding machine)
A centerless grinding machine as an embodiment of the present invention shown in FIG. 1 includes an adjusting grindstone 1, a grinding grindstone 2, a blade 4, a control device 20, a first actuator 41, a second actuator 42, and the like. , A third actuator 43.

  The adjusting grindstone 1 has a substantially cylindrical shape and is supported by an adjusting grindstone driving mechanism so as to be rotatable around an axis O1 (axis parallel to the Z axis). The adjusting grindstone driving mechanism is supported by the adjusting grindstone slider 11 so as to be able to reciprocate along a horizontal direction (± X direction (and further ± Z direction if necessary)) or a plane inclined with respect to a horizontal plane. The adjusting grindstone slider 11 is driven by the first actuator 41. The adjusting grindstone slider 11 is mounted on the bed via the base 10. The adjusting grindstone slider 11 may be directly mounted on the bed. In the vicinity of the adjusting grindstone 1, an adjusting grindstone dressing device for dressing the outer peripheral surface thereof may be provided.

  The grinding wheel 2 has a substantially cylindrical shape, is disposed so that the outer peripheral surface thereof faces the outer peripheral surface of the adjusting wheel 1, and can be rotated around the axis O2 (axis parallel to the Z axis) by the grinding wheel driving mechanism. It is supported by. The grinding wheel driving mechanism can be reciprocated along, for example, a horizontal direction (± X direction (or ± Z direction if necessary)) or a plane inclined with respect to a horizontal plane by a grinding wheel slider 12 mounted on the bed. It is supported. The grinding wheel slider 12 is driven by the second actuator 42. In the vicinity of the grinding wheel 2, a grinding wheel dressing device for dressing the outer peripheral surface thereof may be provided.

  By supplying the workpiece W between the adjusting wheel 1 and the grinding wheel 2, the three contacts of the workpiece W and each of the adjusting wheel 1, the grinding wheel 2 and the blade 4 are appropriately positioned, and the adjusting wheel 1 or the grinding wheel A desired grinding result is realized by cutting 2 in the radial direction of the workpiece W. A line segment L connecting the center of the adjusting grindstone 1 (axis line O1) and the center of the grindstone 2 (axis line O2) in the XY plane is parallel to the X axis, and the center Ow of the workpiece W is above the line segment L. To position.

  The blade 4 is disposed between the adjusting wheel 1 and the grinding wheel 2. The blade 4 is fixed to a workrest 6 mounted on the bed. Above the blade 4, there is provided an upper pressing plate 5 that is driven up and down by a third actuator 43 to press the workpiece W from above. The workrest 6 is provided with an external force sensor 8 that outputs a signal corresponding to an external force acting on the blade 4 (or a strain amount of the workrest 6). The external force sensor 8 is constituted by a strain gauge, for example.

  When the mass of the workpiece W is small, the external force acting on the blade 4 represented by the output signal of the external force sensor 8 becomes less than or less than the reference value, and it may be difficult to accurately detect the decrease in the external force. The upper pressing plate 5 and the third actuator 43 that drives the upper pressing plate 5 cause the external force to act on the workpiece W so that the external force acting on the blade 4 represented by the output signal of the external force sensor 8 is equal to or greater than a reference value. Is configured. By this external force acting mechanism, the above-described situation can be reliably avoided, and an upward force received by the workpiece W, that is, a decrease in the external force can be reliably detected by the contact between the grinding wheel 2 and the workpiece W. For example, as shown in FIG. 3, the external force F is substantially constant until the contact time t = t1 between the grinding wheel 2 and the workpiece W, but is changed after the time t = t1. Is detected.

  In addition, when the mass of the workpiece | work W is large enough, it is not necessary to contact the upper pressing plate 5 with the workpiece | work W, and the upper pressing plate 5 and the actuator which drives this may be abbreviate | omitted. The driving direction of the upper pressing plate 5 is not limited to the vertical direction (vertical direction), and may be inclined with respect to the vertical direction as long as it can function as an external force acting mechanism as described above, and the driving track shape is linear. Instead, it may be curved.

  The control device 20 is configured by a computer (a CPU (arithmetic processing unit), a memory (storage device) such as a ROM or a RAM, an input / output I / F circuit, etc.). The control device 20 controls operations of the first actuator 41, the second actuator 42, and the third actuator 43 in addition to the adjusting wheel driving mechanism and the grinding wheel driving mechanism.

(Control method for centerless grinding machine (setting of grinding wheel in-situ position))
By controlling the operation of the first actuator 41, the adjusting grindstone slider 11 and the adjusting grindstone 1 mounted thereon are moved in the + X direction or the -X direction, and the distance between the adjusting grindstone 1 and the blade 4 in the X direction. Is adjusted according to the diameter of the workpiece W (FIG. 2 / STEP02). At this time, the adjusting grindstone 1 is maintained in a state where its rotation is stopped. After the adjustment of the interval, the operation of the first actuator 41 is stopped. By supplying the workpiece W between the outer peripheral surface of the adjusting grindstone 1 and the inclined surface (upper surface) of the blade 4, the workpiece W is supported by each of the inclined surface of the blade 4 and the outer peripheral surface of the adjusting grindstone 1. (FIG. 2 / STEP04).

  At this time, by controlling the operation of the third actuator 43, the upper pressing plate 5 is driven to move downward, and the upper pressing plate 5 is pressed downward. The resultant force of gravity acting on the work W and the pressing force from the adjusting grindstone 1 acts on the inclined surface of the blade 4 as an external force, and the work rest 6 supporting the blade 4 is distorted and a signal corresponding to the amount of distortion. Is output from the external force sensor 8 as a signal corresponding to the external force. At this stage, the output signal of the external force sensor 8 is substantially constant.

  It is determined whether or not the external force acting on the blade 4 represented by the output signal of the external force sensor 8 is greater than or equal to a reference value. If the determination result is negative, the upper presser plate 5 is driven downward, and the external force is The workpiece W may be pressed downward by the third actuator 43 and the upper pressing plate 5 so as to be equal to or higher than the reference value.

  The position of the adjusting grindstone 1 in the X direction so that the blade 4 and the workpiece W are brought into contact with each other at a predetermined position from the upper end along the inclined surface of the blade 4 (for example, 1/3 of the entire length of the inclined surface). May be fine-tuned.

  In this state, the control device 20 controls the operation of the second actuator 42 to drive the grinding wheel slider 12 and the grinding wheel 2 mounted thereon forward in the + X direction relative to the bed (see FIG. 2 / STEP06). At this time, since the operation of the first actuator 41 is stopped as described above, the adjusting grindstone 1 and the blade 4 are fixed to the bed. That is, the operation of the second actuator 42 is controlled so that the distance between the adjustment grindstone 1 and the grinding wheel 2 is reduced without changing the distance between the adjustment grindstone 1 and the blade 4. Further, the grinding wheel 2 in addition to the adjusting wheel 1 is maintained in a state where its rotation is stopped.

  It is determined whether or not the external force acting on the blade 4 represented by the output signal of the external force sensor 8 has decreased or has exceeded the first threshold value in the process of narrowing the interval between the adjusting wheel 1 and the grinding wheel 2 (FIG. 2 / STEP08). The decrease in the external force acting on the blade 4 represented by the output signal of the external force sensor 8 (or a decrease beyond the first threshold value) is that the workpiece W rises due to the grinding wheel 2 coming into contact with the outer peripheral surface of the workpiece W. This means that the force acting on the blade 4 from the workpiece W has decreased. If the determination result is negative (FIG. 2 / STEP08... NO), the grinding wheel 2 is continuously driven forward in the + X direction (FIG. 2 / STEP06).

  On the other hand, when the determination result is affirmative (FIG. 2 / STEP08... YES), the grinding wheel 2 is driven backward in the −X direction (FIG. 2 / STEP10). That is, the operation of the second actuator 42 is controlled so that the interval between the adjusting grindstone 1 and the grinding grindstone 2 is widened. It is determined whether or not the separation distance or the retraction amount of the grinding wheel 2 has reached a predetermined value (for example, 50 [μm]) in the process in which the distance between the adjusting wheel 1 and the grinding wheel 2 is increased (FIG. 2 / STEP 12). . The position of the grinding wheel 2 is measured using, for example, a position sensor that outputs a signal corresponding to the operation amount of the second actuator 42.

  If the determination result is negative (FIG. 2 / STEP 12... NO), the grinding wheel 2 is continuously driven backward in the −X direction (FIG. 2 / STEP 10).

  If the determination result is affirmative (FIG. 2 / STEP 12... YES), the operation of the second actuator 42 is stopped to stop the grinding wheel slider 12 and the grinding wheel 2 mounted thereon ( FIG. 2 / STEP 14). This stop position is stored and held in the storage device constituting the control device 20 as the original position of the grinding wheel 2.

(Centerless grinding machine control method (workpiece grinding))
While the workpiece W is supported by the adjusting grindstone 1 and the blade 4 and is separated from the grinding grindstone 2 (see FIG. 1), the control device 20 controls the operation of the second actuator 42, whereby the grinding grindstone. 2 is driven forward at a reference speed in the + X direction. That is, the relative approach speed of the adjusting grindstone 1 and the grinding grindstone 2 is controlled to the reference speed. Thereby, the space | interval of the adjustment grindstone 1 and the grinding stone 2 and by extension, the space | interval of the grinding stone 2 and the workpiece | work W are gradually narrowed. In this process, it is determined whether or not the external force acting on the blade 4 represented by the output signal of the external force sensor 8 has decreased or has exceeded a second threshold value.

  If the determination result is negative, the grinding wheel 2 is continuously driven forward at a reference speed in the + X direction. On the other hand, when the determination result is affirmative, the control device 20 controls the operation of the second actuator 42 to reduce the forward drive speed of the grinding wheel 2. That is, the relative approach speed of the adjusting grindstone 1 and the grinding grindstone 2 is decelerated from the reference speed. As a result, the advance speed of the grinding wheel 2 is decelerated when the grinding wheel 2 comes into contact with the workpiece W. Therefore, the advance speed of the grinding wheel 2 is reduced when the grinding wheel 2 is separated from the workpiece W. The time required for grinding the workpiece W can be shortened as compared with the case where it is performed (when the air cut area is large).

  The operations of the adjusting wheel driving mechanism and the grinding wheel driving mechanism are controlled so that the adjusting wheel 1 rotates clockwise around the axis O1 and the grinding wheel 2 rotates clockwise around the axis O2. In this process, while the workpiece W rotates counterclockwise around the axis Ow, it is ground or cut from the outer periphery by the grinding wheel 2 decelerated by the contact with the workpiece W as described above.

(Other embodiments of the present invention)
In the embodiment, the adjustment grindstone slider 11 mounted on the base 10 is driven by the first actuator 41 in a state where the blade 4 is fixed to the bed via the work rest 6 and the base 10. Thus, the distance between the adjustment grindstone 1 and the blade 4 in the X direction is adjusted. However, as another embodiment, instead of driving the adjustment grindstone slider 11 to the base 10 or the bed (in this case, the adjustment grindstone slider 11 is In addition, the blade 4 is driven with respect to the base 10 or the bed separately from the adjusting wheel 1 so that the adjusting wheel 1 and the blade are fixed. The interval in the X direction of 4 may be adjusted.

  In the embodiment, the distance between the adjustment grindstone 1 and the grinding wheel 2 is adjusted so that the distance between the adjustment grindstone 1 and the blade 4 does not change when the grinding wheel slider 12 is driven by the second actuator 42. As another embodiment, instead of driving the grinding wheel slider 12 to the bed (in this case, the grinding wheel slider 12 is fixed to the bed as a grinding wheel base), or in addition, the base 10 is a lower slider. The distance between the adjusting grindstone 1 and the grinding grindstone 2 in the X direction may be adjusted.

DESCRIPTION OF SYMBOLS 1 ... Adjusting whetstone 1 ... Grinding whetstone, 4 ... Blade, 5 Upper presser plate (external force action mechanism), 6 ... Work rest, 8 ... External force sensor, 10 ... Base, 11 ... Adjusting whetstone slider, 12 ... Grinding whetstone slider , 20 ... control device, 41 ... first actuator, 42 ... second actuator, 43 ... third actuator (external force acting mechanism), W ... work.

Claims (5)

A cylindrical grinding wheel, a cylindrical adjusting wheel, a blade disposed between the grinding wheel and the adjusting wheel, a first actuator that adjusts a distance between the adjusting wheel and the blade, and the adjusting wheel A second actuator that adjusts the distance between the grinding wheel and the adjusting wheel without changing the distance between the blade and the blade, and a control device that controls the operation of each of the first actuator and the second actuator. A centerless grinding machine,
An external force sensor that outputs a signal corresponding to the external force acting on the blade;
The controller controls the first actuator so that a workpiece is supported between an inclined surface, which is an upper surface of the blade, and an outer peripheral surface of the adjusting grindstone by adjusting a distance between the adjusting grindstone and the blade. Control the operation,
The operation of the second actuator is such that the distance between the grinding wheel and the adjusting wheel is reduced from the state where the workpiece is supported between the inclined surface which is the upper surface of the blade and the outer peripheral surface of the adjusting wheel. Control
It is determined whether or not the output of the external force sensor has decreased in the process in which the interval between the grinding wheel and the adjustment wheel is narrowed, and the determination result is positive. A centerless grinding machine, wherein the operation of the second actuator is controlled so as to change the change mode of the interval with the adjusting grindstone. The centerless grinding machine according to claim 1,
The controller controls the operation of the second actuator so as to stop after widening the interval between the grinding wheel and the adjustment wheel to a predetermined value, as a requirement that the determination result is affirmative, A centerless grinding machine, wherein the stop position is stored and held as the original position of the grinding wheel. The centerless grinding machine according to claim 1 or 2,
Centerless grinding characterized in that the control device controls the operation of the second actuator so that the approaching speed between the grinding wheel and the adjusting wheel is reduced on the condition that the determination result is affirmative. Machine. In the centerless grinding machine according to any one of claims 1 to 3,
An external force acting mechanism for applying an external force to the workpiece so that an output of the external force sensor is increased in a state where the workpiece is supported between an inclined surface which is an upper surface of the blade and an outer peripheral surface of the adjusting grindstone. A centerless grinding machine further comprising: A control method for a centerless grinding machine comprising: a cylindrical grinding wheel; a cylindrical adjusting wheel; and a blade disposed between the grinding wheel and the adjusting wheel,
A step of supporting a workpiece between the inclined surface which is the upper surface of the blade and the outer peripheral surface of the adjusting grindstone by adjusting the interval between the adjusting grindstone and the blade;
From the state where the workpiece is supported between the inclined surface which is the upper surface of the blade and the outer peripheral surface of the adjusting grindstone, the grinding wheel and the adjusting grindstone are not changed without changing the interval between the adjusting grindstone and the blade. The process of narrowing the interval between
Measuring an external force acting on the blade in the process of narrowing the interval between the grinding wheel and the adjusting wheel;
Determining whether the external force has decreased; and
A control method for a centerless grinding machine, including a step of changing a change mode of an interval between the grinding wheel and the adjusting wheel on the condition that the determination result is affirmative.