JP7492751B2 - Grinding wheel holding device and grinding device - Google Patents

Description

The present invention relates to a grinding wheel holding device that holds a grinding wheel when pressing the grinding wheel to grind an object to be ground, and a grinding device.

Grinding the surface of a workpiece with a circular outer circumference in cross section is performed by pressing a grinding wheel against the surface of the rotating workpiece to be ground. Workpieces whose surfaces are ground are often used as parts for precision instruments and various machines, and require not only high grinding accuracy but also uniformity in the individual grinding. Furthermore, when the workpiece is a mass-produced item, shortening the cycle time is required from a cost perspective.

In response to these requirements for grinding the surface of the workpiece, for example in the grinding process of the end face of a ferrule, the applicant has proposed an end face grinding device in which a speed control mechanism is used to move the grinding wheel toward the workpiece when pressing the grinding wheel against the workpiece, and a constant pressure cutting mechanism is used to press the grinding wheel after it reaches the workpiece (Patent Document 1).
In the end face grinding device proposed in Patent Document 1, the speed control mechanism is composed of a ball screw, and the constant pressure cutting mechanism is composed of an air cylinder. The speed control mechanism moves the grindstone (grindstone head) toward the workpiece while suppressing the free extension of the rod in the air cylinder that presses the grindstone against the workpiece with a slider (an integral part of the ball screw and the nut), and continues to move the nut for a while even after the grindstone reaches the workpiece.

Once the grinding wheel reaches the workpiece, the air cylinder of the constant pressure cutting mechanism releases the restriction on the extension of the rod by the speed control mechanism, and the air pressure inside the cylinder presses the grinding wheel against the workpiece.
This end face grinding device uses a distance sensor to detect the distance between the grindstone head and the slider, that is, the movement distance of the nut after the grindstone comes into contact with the workpiece and its movement is restricted.The device then stores the position of the nut when the distance between the grindstone head and the slider reaches a set value, and refers to this stored position for the operation of the nut when grinding the next workpiece.

As a result, the end face grinding device proposed in Patent Document 1 is able to quickly advance the grinding wheel to a position very close to a new workpiece even if the grinding wheel becomes worn, and is said to be able to shorten the time that is not contributing to grinding.

JP 2005-205525 A

In the end face grinding device in Patent Document 1, the nut of the ball screw in the speed control mechanism and the rod of the pneumatic cylinder in the constant pressure cutting mechanism move together before the grinding wheel reaches the workpiece, and the distance that the distance sensor should indicate is essentially zero. However, the mounting position of the distance sensor is adjusted so that a slight gap is formed in the part to be detected at this time (paragraph 0024).

This is because when there is no gap or the gap is smaller than a certain value, the distance sensor cannot detect the distance accurately.
For this reason, the control device of this end face grinding device determines that the grindstone has reached the workpiece when the distance sensor detects a distance greater than the detection error and the vibration of the device, etc., relative to the initial gap distance formed. Therefore, the control device determines that the grindstone has reached the workpiece when the distance sensor detects a distance greater than a set value, and stores the position of the nut at this time. However, it is not clear whether this stored nut position is the exact position where the grindstone actually reached the workpiece.

Furthermore, in the end face grinding device in Patent Document 1, the value of the aforementioned "slight gap" changes due to expansion and contraction of the detection target part caused by temperature changes in the environment in which it is installed, so the position of the nut (on the ball screw) when the grinding wheel reaches the workpiece as determined by the control device is also unstable.
The end face grinding device proposed in Patent Document 1 aims to memorize the previous (=previous) position of the nut to control the operation of the grindstone (nut) for the next workpiece, always moving the grindstone the same distance and in the same time relative to the workpiece, thereby stabilizing the cycle time. However, the problem of variations in cycle time and grinding time (grinding quality) arose due to the unstable grasp of the position of the nut (on the ball screw) when the grindstone reaches the workpiece, i.e., the position where the grindstone hits the workpiece.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a grinding wheel holding device and grinding device that can accurately determine when the grinding wheel reaches the workpiece, stabilize the cycle time, and achieve uniform grinding quality.

The grindstone holding device according to the present invention is used in a grinding process in which a plurality of workpieces are replaced one by one.
The grindstone holding device includes a base, a grindstone contact device, a grindstone rotation device, a moving body, an air cylinder, and a control device. The base holds the grindstone contact device, the air cylinder, and the grindstone rotation device. The grindstone contact device includes a transfer motor integrated with the base and a ball screw driven by the transfer motor. A stopper that protrudes in a direction perpendicular to the screw axis of the ball screw is integrated with the nut of the ball screw.
One end of a guide rod extending parallel to the screw shaft toward the transfer motor is fixed to the protruding end of the stopper.

The grindstone rotating device includes a grindstone rotating motor and a transmission device connected to the grindstone rotating motor to rotate a grindstone holder capable of holding a grindstone around an axis parallel to the screw shaft. The movable body supports the grindstone rotating device and is reciprocatable relative to the base in the direction of the screw shaft, and includes a pressed part having a surface facing the surface of the stopper facing the side opposite to the side where the grindstone holder is located, and a guide hole through which a guide rod movably passes. The air cylinder is fixed to the base and is arranged so that the rod can press the pressed part toward the grindstone holder.

The guide rod is connected to one pole of the power supply and is electrically insulated from the guide hole.
When a voltage is applied between the guide rod and the pressed portion and the pressed portion is in contact with the stopper, electricity can flow between them and the current flowing through the pressed portion can be earthed via the moving body .
During grinding of a workpiece, the control device of the grinding wheel holding device moves the nut from its waiting position toward the grinding wheel holder at a first speed using the grinding wheel abutment device while restricting the extension of the rod with a stopper via the pressed part, and then moves it at a second speed slower than the first speed, and during this time detects whether or not electricity is flowing between the pressed part and the stopper, stores the position of the nut when the electricity is cut off as the work abutment position, and determines the waiting position to which the nut is to be retracted in preparation for grinding the next workpiece based on the stored work abutment position.

Another grinding wheel holding device according to the present invention is configured so that a voltage is applied between the pressed portion and the stopper so that electricity can flow between them when they are in contact, and is also configured so that the load current value when the grinding wheel rotation motor is rotating can be measured.

When grinding the workpiece, the control device detects whether or not electricity is flowing between the pressed part and the stopper, and detects the load current value of the grinding wheel rotation motor. Then, when electricity is cut off or the load current value exceeds a set value, the control device stores the position of the nut as the workpiece abutment position, and determines the retreat position to which the nut should be retracted in preparation for grinding the next workpiece based on the stored workpiece abutment position.

The grinding device according to the present invention has the above-mentioned grindstone holding device and a workpiece holding device that holds and rotates a workpiece.

The present invention provides a grinding wheel holding device and grinding machine that can accurately determine when the grinding wheel reaches the workpiece, stabilize the cycle time, and achieve uniform grinding quality.

FIG. 1 is a plan view of a grindstone holding device. FIG. 2 is a partial cross-sectional side view of the grindstone holding device. FIG. 3 is a flow chart showing the operation of the grinding wheel head controlled by the control device. FIG. 4 is a diagram showing the operation of the grinding wheel head when grinding a workpiece. FIG. 5 is a diagram showing the relationship between the movement time of the grindstone, the amount of current flow between the contacts, and the movement distance of the grindstone in the grinding process. FIG. 6 is a flow chart showing the operation of the grinding wheel head using the load current value of the grinding wheel rotating motor as an index. FIG. 7 is a diagram showing the relationship between the movement time of the grindstone, the load current value of the grindstone rotation motor, and the movement distance of the grindstone in the grinding process. FIG. 8 is a flow chart showing the operation of the grinding head when the energization detection method and the motor load detection method are combined. FIG. 9 is a partial cross-sectional view showing an insulating structure in the vicinity of the contact.

FIG. 1 is a plan view of the grindstone holding device 1, and FIG. 2 is a partial cross-sectional side view of the grindstone holding device 1. As shown in FIG.
The grindstone holding device 1 includes a base 11, a rotating table 12, a lateral movement support table 13, a grindstone head 2, and a control device.
The base 11 is formed of a thick plate material as a whole, and the rotating table 12, the lateral movement support table 13, and the grinding wheel head 2 are provided thereon in this order. The base 11 is a special hexagon with two right angles and four obtuse angles in a plan view. The base 11 is provided with a rotating shaft 14 whose axis is in the thickness direction and is located near one of the inner vertices of the four obtuse angles.

The rotating table 12 is formed from a thick plate material overall, and in plan view has a roughly pentagonal shape in which one side of a roughly rectangular shape is connected to the base of an obtuse triangle. The rotating table 12 is integrated with the base 11 so that a portion near the apex of the triangle can rotate around the rotation axis 14. The rotation of the rotating table 12 is performed by an angle adjustment knob 15. The rotation of the rotating table 12 relative to the base 11 is limited by clamp grooves 16, 16 that are provided on the top surface of the rotating table 12 and have an arc shape in plan view centered on the rotation axis 14, and by multiple clamp bolts 17, ..., 17.

The lateral movement support base 13 is fixed to the upper surface of the rotating base 12, and has a dovetail 21 on its upper surface. The dovetail 21 extends in a direction perpendicular to a screw shaft 23 of a ball screw 22, which will be described later.
The grindstone head 2 comprises a base 5, a grindstone contact device 6, a grindstone pressing device 7, a moving body 8, and a grindstone rotating device 9, etc.
The base 5 is a framework (frame, base) that holds the grindstone contact device 6, the grindstone pressing device 7, the grindstone rotating device 9, etc. A dovetail groove 26 is provided below the base 5. The dovetail groove 26 is engaged with the dovetail 21 of the lateral movement support base 13, and the base 5 can move back and forth in the direction in which the dovetail 21 extends. The reciprocating movement of the base 5 is limited by clamp bolts 27, 27.

The grindstone contact device 6 is a device that moves the grindstone 61 provided on the grindstone head 2 to the grinding surface of the workpiece and contacts it when grinding begins, and moves the grindstone 61 back to a waiting position after grinding is completed. The grindstone contact device 6 is equipped with a ball screw 22 and a transfer motor 24. One end of the screw shaft 23 of the ball screw 22 is connected to the transfer motor 24. The transfer motor 24 is fixed to the base 5 at the end opposite the rotating shaft 14 in a plan view (FIG. 1) in the grindstone holding device 1, with the drive shaft facing the rotating shaft 14 side. Therefore, the screw shaft 23 extends toward the rotating shaft 14 as a whole. The transfer motor 24 is a servo motor, and its rotation is controlled by a control device (not shown).

A thick plate-like stopper block 29 that protrudes upward and is generally perpendicular to the screw shaft 23 is integrated with the nut 25 of the ball screw 22. A guide rod 30 is attached to the upper end of the stopper block 29. The guide rod 30 is a round bar, one end of which is fixed to the stopper block 29 and which extends parallel to the screw shaft 23 toward the transfer motor 24.
A stopper bolt 31 is screwed into the stopper block 29 below the position where the guide rod 30 is attached, with its head projecting toward the transfer motor 24 side.

The stopper block 29 includes an insulating sheet 32 made of a non-conductor and disposed between the stopper bolt 31 and the nut 25. The insulating sheet 32 electrically insulates the upper side of the stopper block 29 above the stopper bolt 31 from the lower side connected to the nut 25.
The grindstone pressing device 7 serves to press the grindstone 61 against the workpiece during grinding. An air cylinder is used for the grindstone pressing device 7. The air cylinder has its cylinder 35 fixed to the base 5 so that its reciprocating direction (direction in which the rod 34 extends) is parallel to the screw shaft 23 of the ball screw 22. The air cylinder is disposed at a position where the extension of the rod 34 protruding toward the rotating shaft 14 abuts against the head of the stopper bolt 31.

The movable body 8 is a frame that supports the grindstone rotating device 9. The movable body 8 is connected to the base 5 by a linear guide (not shown), and can move back and forth relative to the workpiece in a direction perpendicular to the extension direction of the dovetail grooves 26 relative to the base 5 during grinding of the workpiece.
The movable body 8 has a pressed portion 36 for transmitting the pressing force of the rod 34 in the grindstone pressing device 7 to the grindstone 61. The pressed portion 36 is located between the tip of the rod 34 protruding toward the rotary shaft 14 and the head of the stopper bolt 31. The movable body 8 has a guide hole 37 through which the guide rod 30 integrated with the nut 25 (of the ball screw 22) passes.

The inner diameter of the guide hole 37 is larger than the outer diameter of the guide rod 30, and a sleeve member 38 made of a non-conductor is placed in the gap. The sleeve member 38 has a flange-shaped portion at one opening of the cylinder. The sleeve member 38 is inserted into the guide hole 37 from the other opening, and the guide rod 30 passes through its inside. The sleeve member 38 is made of a material that is self-lubricating and electrically insulating, such as a fluororesin such as FEP or PTFE.

The combination of the guide rod 30 and the guide hole 37 allows the nut 25 , which is integrated with the stopper block 29 , to move smoothly relative to the moving body 8 .
The pressed portion 36 of the moving body 8 moves as the rod 34 of the grindstone pressing device 7 extends.
The grindstone rotating device 9 is a device related to the rotation of the grindstone 61 used in grinding. The grindstone rotating device 9 includes a grindstone rotating motor 39, a precision bearing 40, a transmission device 41, a grindstone holder 42, and the like.

The grindstone rotation motor 39 is attached to the upper part of the moving body 8 so that its drive shaft is parallel to the rod 34 and located on the side of the rotation shaft 14 .
The precision bearing 40 supports a rotating shaft having one end integrated with the grindstone holder 42, and is long in the axial direction to prevent wobble during rotation of the grindstone 61 held by the grindstone holder 42. The precision bearing 40 is disposed so that the rotating shaft it supports is an extension of the axis of the rod 34 of the grindstone pressing device 7, and is integrated inside the movable body 8. The movable body 8 rotatably holds the grindstone 61, and moves back and forth together with the grindstone 61 relative to the base 5.

The transmission device 41 is composed of two pulleys 43, 44 and a timing belt 45. One pulley 43 is fixed to the drive shaft of the grindstone rotation motor 39, and the other pulley 44 is fixed to a rotation shaft protruding from the precision bearing 40, and the two pulleys 43, 44 are connected by the timing belt 45. A servo motor is used for the grindstone rotation motor 39.
The grindstone rotating device 9 reciprocates together with the moving body 8 .

In the grindstone holding device 1 configured as described above, the stopper block 29 (stopper bolt 31) of the grindstone contact device 6 limits the extension of the rod 34 of the grindstone pressing device 7. In addition, a servo motor is used as the grindstone rotation motor 39, so the movement of the nut 25 can be controlled as desired, and the control device can appropriately control the movement and movement speed of the grindstone on the moving body 8 toward the workpiece to be ground.

The grindstone rotating device 9, together with the workpiece holding device 65, etc., constitutes a grinding device.
The grindstone holding device 1 is configured such that a voltage is applied between the stopper bolt 31 and the pressed portion 36, and when they come into contact, a current of several mA flows between them. When performing grinding processing, the control device detects whether or not electricity is flowing between the stopper bolt 31 and the pressed portion 36. The stopper bolt 31 (its head) and the pressed portion 36 are collectively referred to as the "contact point."

Next, a description will be given of a grinding process for an end face of an object to be ground (hereinafter referred to as "workpiece W") using the grindstone holding device 1. During grinding, the workpiece W is held by the workpiece holding device 65 and rotated, and its rotation axis is parallel to the rotation axis of the grindstone 61 or inclined at a slight angle.
FIG. 3 is a flow chart showing the operation of the grinding head 2 controlled by the control device, and FIG. 4 is a diagram showing the operation of the grinding head 2 when grinding a workpiece W.

When the control device is instructed to start the grinding process from a standby state of the grinding device, it checks whether the grinding wheel 61 is already in the waiting position, and if the grinding wheel 61 is not in the waiting position, it operates the transfer motor 24 to retract the nut 25 (of the ball screw 22) so that the grinding wheel 61 retracts to the initial set waiting position (Figure 4 (a)).
Next, when the control device confirms that the workpiece W is held by the workpiece holding device 65, it operates the transfer motor 24 to move the grindstone 61 toward the workpiece W (S1). The reciprocating movement of the grindstone 61 is achieved by the movement and retreat of the nut 25 of the ball screw 22 (grindstone contact device 6).

Here, the movement of the grindstone 61, the nut 25, etc. towards the workpiece W is referred to as "movement," and the movement of the grindstone 61, the nut 25, etc. in the opposite direction is referred to as "retreat."
The grinding wheel 61 moves at high speed until it is very close to the workpiece W, and then moves at a low speed to prevent damage to the grinding wheel 61 due to an impact when it reaches the workpiece W. For the first workpiece W after the start of the grinding process, the grinding wheel 61 is moved at a low speed throughout the entire movement process, or moved at high speed a preset distance and then moved at a low speed, etc.

When the grindstone 61 moves, in the grindstone holding device 1 , the pressed portion 36 of the moving body 8 is pressed toward the workpiece W by the rod 34 of the grindstone pressing device 7 , but the stopper block 29 prevents the moving body 8 from moving freely.
While the grinding wheel 61 moves at a low speed, the control device monitors whether or not a current is flowing between the stopper bolt 31 and the pressed portion 36. When the grinding wheel 61 reaches the grinding surface of the workpiece W (FIG. 4(b)), the movement of the grinding wheel 61 is blocked by the workpiece W, and the moving body 8 stops its movement.

The control device continues to operate the transfer motor 24 and the nut 25 continues to move further. As the nut 25 moves further, the stopper bolt 31 is released from contact with the pressed portion 36 of the stopped moving body 8, and the current between them is cut off. The control device detects that the current has been cut off (NO in S2) and stores the position of the nut 25 at this time (S3).
The control device stops the movement of the nut 25 after moving the nut 25 a predetermined distance D2 after the current is cut off (S4, FIG. 4(c)), and waits for the processing time until grinding of the workpiece W is completed (NO in S5).

When grinding of the workpiece W is completed (YES in S5), the control device operates the transfer motor 24 of the grindstone contact device 6 to retract the grindstone 61 to the waiting position (S6).
When the control device confirms that the next unground workpiece W is held by the workpiece holding device 65 (YES in S7), it first moves the grinding wheel 61 at high speed from the waiting position toward the workpiece W (S8), and then moves the workpiece W at a low speed to bring the grinding wheel 61 into contact with the surface of the workpiece W to be ground (S9).

4A to 4C, the high-speed and low-speed movements of the nut 25 (grindstone 61) from the retreat position are performed in the same manner as in Fig. 4A to 4C when grinding the second or subsequent workpiece W. The retreat distance and high-speed movement distance of the nut 25 at that time are determined based on the position (S3) of the nut 25 stored when the immediately previous workpiece W was ground.
For example, the retraction distance of the nut 25 from the position where the grinding wheel 61 reaches the workpiece W during grinding to replace the workpiece W with the next workpiece W is 10.5 mm, and the high-speed movement distance of the nut 25 from the retracted position to the workpiece W after replacement is 10 mm. The low-speed movement distance is a distance longer than 0.5 mm (D1 in FIG. 4 is approximately 10.5 mm).

The low-speed travel distance is set to be greater than "10.5 - high-speed travel distance = 0.5 (mm)" in order to move the nut 25 at a low speed even after the grinding wheel 61 contacts the workpiece W, thereby cutting off the electrical current between the stopper bolt 31 and the pressed portion 36.
The retreat distance is based on the position (S3) of the nut 25 when current was cut off during the previous grinding, and this reference position gradually changes due to wear of the grindstone 61 and the like while grinding many workpieces W. The position (D1+D2) obtained by adding the distance traveled by the nut 25 after it has moved further after the grindstone 61 has reached the workpiece W in S5 of Fig. 3 (D2 in Fig. 4) is not a reference for determining the retreat position, etc. of the nut 25.

The rotation of the grindstone 61 for grinding by the grindstone rotation motor 39 may be limited to during low-speed movement (S) and grinding (NO in S5), or may be performed throughout the entire grinding process shown in FIG.
5A and 5B are diagrams showing the relationship between the movement time of the grindstone 61, the amount of current flowing between the contacts, and the movement distance of the grindstone in the grinding process of the workpiece W. In Fig. 5A, (a) is a diagram showing a mechanism for detecting the current flowing between the contacts.

The movement conditions of the nut 25 in FIG. 5 are a high-speed movement distance of 10 mm, a required time of 0.4 seconds, a low-speed movement distance of 0.5+α mm, and a required time of 0.5 seconds to move 0.5 mm. As can be seen from FIG. 5, even after the grinding wheel 61 reaches the workpiece W, the nut 25 continues to move at a low speed by itself, and the moment the grinding wheel 61 stops moving, the amount of current between the contacts drops sharply to zero. This makes it possible to accurately detect the position of the nut 25 when the grinding wheel 61 reaches the workpiece W. In addition, since the time when the grinding wheel 61 reaches the workpiece W is accurately grasped and grinding is performed for a certain period of time starting from this time, the quality of grinding is consistent even when grinding consecutive objects to be ground. In addition, accurate detection of the position of the nut 25 when it reaches the workpiece W makes the retreat distance of the grinding wheel, etc., consistent, and the cycle time is also stable.

On the other hand, in detection methods using distance sensors, the detected distance value after the grinding wheel reaches the workpiece does not increase (change) suddenly because the nut moves at a low speed (see, for example, dashed line J in Figure 5). In addition, since the distance sensor has a slight gap formed in the detection target area from the beginning, it is only when it detects a distance that clearly exceeds the range of variation caused by detection noise and vibrations caused by the grinding wheel rotation motor, etc., that it is determined that the grinding wheel has reached the workpiece. For this reason, the detected nut position is shifted toward the workpiece side from the actual position of the nut when the grinding wheel actually reaches the workpiece. In addition, the degree of difference between the actual time when the grinding wheel has reached the workpiece and the time when the detection is determined changes each time and is unstable, making it difficult to know the exact position of the nut and the time when the grinding wheel reached the workpiece by making corrections.

Since the grinding wheel holding device 1 simply determines whether or not electricity is flowing to the contacts, it can detect the position of the nut 25 when the grinding wheel 61 reaches the workpiece W more accurately and stably than a method that determines the distance detected by a distance sensor.
When grinding, for example, the end surface of the workpiece W, the combination of the hardness of the material of the workpiece W and the coarseness of the grinding grains of the grinding wheel may cause the low-speed movement speed of the nut 25 and the erosion speed due to grinding (the retreating speed of the grinding surface of the workpiece W) to match in grinding using the grinding wheel holding device 1, and the contacts may always be in a conducting state. In such a case, the method of detecting the presence or absence of electricity at the contacts shown in FIG. 3 cannot determine when the grinding wheel 61 reaches the workpiece W. However, even in such a case, the grinding wheel rotation motor 39, which continues to rotate from the start of the low-speed movement, is subjected to a load due to grinding when the grinding wheel 61 abuts against the workpiece W, and the load current value increases sharply. By utilizing this, the position of the nut 25 when the grinding wheel 61 reaches the workpiece W can be detected.

Figure 6 is a flowchart showing the operation of the grinding wheel head 2 controlled by the control device using the load current value of the grinding wheel rotation motor 39 as an index, and Figure 7 is a diagram showing the relationship between the movement time of the grinding wheel 61, the load current value of the grinding wheel rotation motor 39, and the grinding wheel movement distance during the grinding process of the workpiece W.
In FIG. 6, when the step number (for example, S3) is the same as that in FIG. 3, the control device performs the same operation as in the method of detecting the presence or absence of current in FIG.

For example, when the nut 25 moves under the same high-speed and low-speed movement conditions as in Figure 5, and the grinding wheel 61 reaches the workpiece W during low-speed movement, the rotation of the grinding wheel 61 is resisted by the workpiece W, and the load current value of the grinding wheel rotation motor 39 increases suddenly (Figure 7). When the control device detects this sudden increase in the motor load current value (load current value equal to or greater than a set value previously stored in the storage device) (YES in S12 in Figure 6), it determines that the grinding wheel 61 has reached the workpiece W and stores the position of the nut 25 at that time.

Like the method using the load current value of the grinding wheel rotation motor 39 as an index, the method using the presence or absence of electricity as an index can accurately and stably detect the position of the nut 25 when the grinding wheel 61 reaches the workpiece W.
By combining the method using the load current value of the grindstone rotating motor 39 as an index with the method using the presence or absence of current as an index, a grindstone holding device with greater versatility can be obtained.

Fig. 8 is a flow chart showing the operation of the grinding wheel head 2 controlled by the control device when these two methods are combined. In Fig. 8, when the step numbers are the same as those in Fig. 3 or Fig. 6, the control device performs the same operation as in Fig. 3 or Fig. 6.
9 is a partial cross-sectional view showing an insulating structure in the vicinity of the contact point. As described above, the "contact point" refers to the stopper bolt 31 (its head) and the pressed portion 36 collectively.

Referring to FIG. 9, the guide rod 30 is connected to a conductor 51 that is continuous with one electrode of a power source. The guide rod 30 is electrically insulated from the guide hole 37 by a sleeve member 38. The stopper bolt 31 is also electrically insulated from the underside (nut 25) of the stopper block 29 by an insulating sheet 32. Either AC or DC power sources can be used.

In the grinding wheel holding device 1, the stopper bolt 31 is in contact with the pressed portion 36 until the grinding wheel reaches the workpiece, and the current is earthed via the guide rod 30, the upper side of the stopper block 29, the pressed portion 36, and the moving body 8. In this state, current flows through the contact point (e.g., YES in S2 in FIG. 3), and the grinding wheel has not yet reached the workpiece.
If the nut 25 continues to move even after the grindstone reaches the workpiece and the extension of the rod 34 is prevented, the contacts separate and the current between the contacts is cut off. Even at this time, the stopper bolt 31 is insulated from the movable body 8 by the sleeve member 38 and the insulating sheet 32.

In the method of detecting the position where the grinding wheel has reached the workpiece using the presence or absence of current flowing through the contact as an indicator, it is necessary to prevent the current from being earthed from a path continuing to one electrode of the power source in the stopper bolt 31 that forms the contact, without passing through the contact. In Fig. 9, the sleeve member 38 and the leading edge seat 32 are responsible for preventing this earthing.
In the above-described embodiment, the grindstone holding device 1 and each component or the overall structure, shape, dimensions, number, material, etc. of the grindstone holding device 1 can be appropriately modified in accordance with the spirit of the present invention.

The present invention can be used in a grinding wheel holding device and a grinding device that holds a grinding wheel when pressing the grinding wheel to grind an object to be ground.

1 Grindstone holding device
5 Base 6 Grindstone contact device 7 Grindstone pressing device (air cylinder)
8: moving body 9: grindstone rotating device 11: base 22: ball screw 23: screw shaft 24: transfer motor 25: nut 29: stopper block (stopper)
30 Guide rod
31 Stopper bolt (stopper)
34 (air cylinder) rod 36 pressed part
37 Guide hole
39 Grindstone rotation motor 41 Transmission device 42 Grindstone holder W Workpiece (object to be ground)

Claims (3)

The grinding machine includes a base, a grinding wheel contact device, a grinding wheel rotation device, a moving body, an air cylinder, and a control device.
the base portion holds the grindstone contact device, the air cylinder, and the grindstone rotation device;
The grindstone contact device includes a transfer motor integrated with the base and a ball screw driven by the transfer motor,
a stopper protruding in a direction perpendicular to the screw shaft of the ball screw is integrated with the nut of the ball screw;
One end of a guide rod extending parallel to the screw shaft toward the transport motor is fixed to the protruding end of the stopper,
the grindstone rotating device includes a grindstone rotating motor and a transmission device connected to the grindstone rotating motor to rotate a grindstone holder capable of holding a grindstone about an axis parallel to the screw shaft;
The moving body is
a grindstone rotating device that supports the grindstone rotating device and is reciprocally movable in the direction of the screw shaft relative to the base,
a pressed portion having a surface facing a surface of the stopper facing the opposite side to the side where the grindstone holder is located;
A guide hole through which the guide rod movably passes,
the air cylinder is fixed to the base and the rod is arranged to be able to press the pressed portion toward the grindstone holder;
The guide rod is connected to one pole of a power source and is electrically insulated from the guide hole, and the stopper is electrically insulated from the nut,
a voltage is applied between the guide rod and the pressed portion, and when the pressed portion and the stopper are in contact with each other, electricity can flow between them, and the current flowing through the pressed portion can be earthed via the moving body,
During grinding of a workpiece, the control device
While restricting the extension of the rod by the stopper via the pressed portion, the nut is moved from its retreated position toward the grindstone holder by the grindstone contact device at a first speed, and then moved at a second speed slower than the first speed;
During this time, the presence or absence of electrical conduction between the pressed portion and the stopper is detected.
The position of the nut when the current flow is interrupted is stored as a work abutment position;
determining a retreat position for retracting the nut in preparation for grinding the next workpiece based on the stored workpiece abutment position;
A grindstone holding device characterized by the above. The grinding machine includes a base, a grinding wheel contact device, a grinding wheel rotation device, a moving body, an air cylinder, and a control device.
the base portion holds the grindstone contact device, the air cylinder, and the grindstone rotation device;
The grindstone contact device includes a transfer motor integrated with the base and a ball screw driven by the transfer motor,
a stopper protruding in a direction perpendicular to the screw shaft of the ball screw is integrated with the nut of the ball screw;
One end of a guide rod extending parallel to the screw shaft toward the transport motor is fixed to the protruding end of the stopper,
the grindstone rotating device includes a grindstone rotating motor and a transmission device connected to the grindstone rotating motor to rotate a grindstone holder capable of holding a grindstone about an axis parallel to the screw shaft;
The grindstone rotating motor is configured so that a load current value during rotation can be measured,
The moving body is
a grindstone rotating device that supports the grindstone rotating device and is reciprocally movable in the direction of the screw shaft relative to the base,
a pressed portion having a surface facing a surface of the stopper facing the opposite side to the side where the grindstone holder is located;
A guide hole through which the guide rod movably passes,
the air cylinder is fixed to the base and the rod is arranged to be able to press the pressed portion toward the grindstone holder;
The guide rod is connected to one pole of a power source and is electrically insulated from the guide hole, and the stopper is electrically insulated from the nut,
a voltage is applied between the guide rod and the pressed portion, and when the pressed portion and the stopper are in contact with each other, electricity can flow between them, and the current flowing through the pressed portion can be earthed via the moving body,
During grinding of a workpiece, the control device
While restricting the extension of the rod by the stopper via the pressed portion, the nut is moved from its retreated position toward the grindstone holder at a first speed by the grindstone contact device, and then moved at a second speed slower than the first speed;
During this time, the presence or absence of current flow between the pressed portion and the stopper is detected, and the load current value of the grindstone rotating motor is detected.
a position of the nut when the current flow is interrupted or when the load current value becomes equal to or greater than a set value is stored as a workpiece contact position;
determining a retreat position for retracting the nut in preparation for grinding the next workpiece based on the stored workpiece abutment position;
A grindstone holding device characterized by the above. The grindstone holding device according to claim 1 or 2,
A grinding apparatus comprising: a workpiece holding device that holds and rotates a workpiece.

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