JPH036442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a balance device that reduces the operating force of a movable detection section of a measuring instrument.

An example in which a conventional balance device is applied to a coordinate measuring machine will be explained based on FIG. 1. In FIG. 1, a surface plate 2 is installed on a base 1, and this surface plate 2
Columns 3 are erected on both sides of the column (only one column 3 is shown in FIG. 1).
A guide rail 4 is provided on each of these columns 3, and a Y-direction air bearing 5 is provided on each of these guide rails 4 so as to be freely slidable. Although not shown, one of the air bearings 5 and the guide rail 4 is provided with a linear gauge (product name; the same applies hereinafter) for detecting displacement in the Y direction, and a horizontal gauge is provided between the two bearings 5. Digit 6 is crossed. A guide rail 7 is placed on this crossbeam 6.
An X-direction air bearing 8 is slidably supported on the guide rail 7, and a linear gauge 9 for detecting X-direction displacement is provided between the guide rail 7 and the bearing 8. There is.

A Z-direction air bearing 10 is fixed to the front surface of the X-direction air bearing 8, and a rectangular sliding shaft 11 serving as a movable detection section is accommodated in the bearing 10 so as to be slidable in the vertical direction. At the lower end of this sliding shaft 11, there is an object to be measured (not shown) placed on the surface plate 2.
At the same time, one end of a wire 13 is fixed to the upper end, and the other end of this wire 13 is extended via a pulley 14 and fixed to a weight 15, and this weight 15 is It is slidably guided and supported within a guide 16 arranged at an angle. These pulley 14, weight 15, guide 16, etc. constitute a balance device, and the sliding shaft 11 can be easily moved.

Note that a linear gauge (not shown) for detecting displacement in the Z direction is provided between the Z direction air bearing 10 and the sliding shaft 11, so that the displacement of the sliding shaft 11 in the Z direction (vertical direction) can be measured. It's summery.

In such a configuration, in order to measure the dimensions of each part of the object to be measured (not shown) placed on the surface plate 2, the sliding shaft 11 is grasped, and the guide rails 4, 7, air bearings 5, Due to the action of 8 and 10, the sliding shaft 11
The gauge head 12 is brought into contact with a plurality of measured points on the object to be measured by freely moving three-dimensionally, and the position of the gauge head 12 at this time is adjusted between the linear gauge 9 in the X direction and the Y and Z directions (not shown). Measured using a linear gauge.

However, in such a conventional balance device, the balance device includes a weight 15 having approximately the same weight as the sliding shaft 11, and a guide 1 that guides the weight 15.
6. It is composed of a pulley 14 and a guide post (not shown) that supports this pulley 14, so
The weight is large, and this large weight is added to the crossbeam 6 and other parts, which adversely affects measurement accuracy, and the arrangement of the pulley 14 has the drawback of increasing the height of the device. In addition, since the gauge head 12 is replaced and used depending on the shape of the object to be measured, its weight changes, but the weight of the weight 15 remains unchanged, so the operability of the sliding shaft 11 is improved. It has the disadvantage that it changes every 12 changes.

In order to overcome the drawbacks of the balance device using a weight, a cylinder type balance device disclosed in Japanese Utility Model Application Laid-Open No. 53-76850 is known. In this system, a vertical shaft that moves up and down is suspended from one end of a wire rope, and the other end of the wire rope is connected to the piston rod of a vertically arranged air cylinder by turning a pulley. Compressed air is supplied to the upper chamber through a pressure regulator, and the weight of the vertical shaft is balanced and supported by the air pressure acting on the upper surface of the piston of the air cylinder.

However, in such a cylinder-type balance device, if the supply of compressed air is stopped due to a failure of the fluid supply source such as compressed air, the air in the upper chamber divided by the piston will flow between the cylinder and the piston. There is a danger that the vertical shaft will fall because it is released into the atmosphere through the gap between the holes and the lower chamber. Furthermore, since reverse upward and downward accelerations occur during upward and downward operations on the vertical axis, there is a drawback in that the operating forces in both directions cannot be made equal.

The purpose of the present invention is to eliminate the drawbacks of the conventional cylinder system, prevent the movable detection part from falling even if the fluid supply is stopped due to a failure of the fluid supply source, etc., and prevent the movable detection part from rising. It is an object of the present invention to provide a balance device for a measuring machine that can equalize the operating force during the lowering operation.

Further, other objects of the present invention are, in addition to the above objects,
It is an object of the present invention to provide a balance device for a measuring machine that can smoothly move a movable detection section up and down without using a special device or the like.

Therefore, in the first invention, the cylinder and
A balance device for a measuring machine, which includes a piston connected to a movable detection part of the measuring machine and slidable within the cylinder, and a damper chamber defined by the piston and the cylinder, which is attached to the piston. , and has a valve body that closes a through hole communicating between the damper chamber and a low-pressure part such as the atmosphere, and when the movable detection part is lowered, the valve body opens due to the pressure difference generated thereby, and the damper chamber is opened. a first valve mechanism that discharges the fluid through the through hole to the low pressure section side, and a pressurized fluid supply that communicates with the high pressure section so as to pressurize the fluid in the damper chamber with a pressure that balances the weight of the movable sections such as the movable detection section and the cylinder. and a valve body that is attached to the cylinder and that closes a through hole that communicates between the damper chamber and a high pressure part side that is communicated with the pressure fluid supply mechanism, and when the movable detection part is raised,
The resulting pressure difference opens the valve body,
and a second valve mechanism that discharges the fluid of the pressure fluid supply mechanism to the damper chamber side through the through hole, and the first valve mechanism and the second valve mechanism are configured so as not to be completely closed. shall be.

Further, in a second invention, in addition to the first invention, the piston has a small hole that is opened and formed on the circumferential surface of the piston and communicates with the damper chamber, and the fluid in the damper chamber is allowed to flow through the small hole. The present invention is characterized by a configuration in which a fluid bearing is added to supply the sliding surfaces between the piston and the cylinder.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2 and 3. Here, the same reference numerals are used for the same or equivalent components as in the conventional example to simplify the explanation.

FIG. 2 shows an example in which the balance device according to the present invention is applied to a three-dimensional measuring machine, in which a surface plate 2 and a pair of columns 3 are installed on a base 1, and a Y on the guide rail 4
A cross beam 6 is supported via a directional air bearing 5 so as to be movable in the Y direction (horizontal direction in the figure). This crossbeam 6
An X-direction air bearing 8 is supported via a guide rail 7 so as to be movable in the X-direction (perpendicular to the plane of the drawing), and a linear gauge 9 for detecting displacement in the X-direction is provided between the bearing 8 and the crossbeam 6. is provided. Also,
A sliding shaft 11 as a movable detection section is attached to the bearing 8 via a Z-direction air bearing 10 in the Z direction (vertical direction in the figure).
It is inserted so that it can be moved freely. A measuring element 12 is removably attached to the lower end of this sliding shaft 11, while a balance device 20 is connected to the upper end via an extension rod 17, a connecting rod 18, and a piston rod 19.
The balance device 20 allows the sliding shaft 11 to be easily moved in the Z direction.

FIG. 3 shows an enlarged view showing a specific example of the internal structure of the balance device 20. As shown in FIG.
In FIG. 3, the balance device includes a cylinder 21. As shown in FIG. This cylinder 21 is composed of a cylindrical body 22 and a cap 23 fitted to one end of this cylindrical body 21.

A piston 24 is slidably inserted into the cylinder 21, and the piston 24 has a cylindrical body 25,
It is composed of a plug body 26 fitted to the lower end of this cylinder body 25. A plurality of through holes 27 are formed in the bottom surface of the plug body 26, and a damper chamber defined by the inside and outside of the piston 24, that is, the inside of the piston 24, and the piston 24 and the cylinder 21 is formed through the through holes 27. 28 is in communication. In addition, a plurality of small holes 29 are perpendicularly formed in the center of the cylinder 25, penetrating through the cylinder 25, and these small holes 2
9 and the through hole 27, the pressure fluid (compressed air) in the damper chamber 28 can be ejected between the circumferential surface of the cylindrical body 25 and the inner surface of the cylinder 21, thereby causing the piston 24 and the cylinder 21 to A so-called fluid (air) bearing is formed on the sliding surface.

A shaft body 26A is erected at the center of the inner end surface of the cylinder body 25 of the plug body 26, and a valve seat 31 made of rubber, synthetic resin, etc. is fixed to the top of the shaft body 26A. A valve body 33 having a through hole 32 is allowed to come into contact with it. This valve body 33 is fixed to a diaphragm 34, and the periphery of this diaphragm 34 is connected to the end of the cylindrical body 25 of the piston 24 and the valve case 3.
It is clamped and fixed between the flange part of 5. A plurality of through holes 36 are formed in the peripheral wall of the valve case 35 to communicate the inside and outside of the valve case 35, and a spring receiver 37 is movably provided in the valve case 35. A compression spring 38 as a biasing means is interposed between the valve element 33 and the diaphragm 34, and the valve element 33 is always biased in a direction to abut against the valve seat 31. Further, an adjusting screw 39 as an adjusting means screwed into the valve case 35 is brought into contact with the spring receiver 37, and by adjusting the adjusting screw 39, the operating pressure of the valve body 33 can be adjusted. On this occasion,
The valve body 33 and the valve seat 31 are prevented from being completely closed by adjusting the pressure of the spring 38 or by providing a groove on the contact surfaces of both members, so that some pressure fluid always flows there. It's like that. In addition, the first valve mechanism 30 is controlled by the valve seat 31, the valve body 33, the diaphragm 34, the valve case 35, the spring receiver 37, the compression spring 38, and the adjustment screw 39.
The first valve mechanism 30 is operated by the pressure difference between the pressure inside the damper chamber 28 and the pressure inside the valve case 35 communicating with a low pressure part such as the atmosphere,
The pressure fluid in the damper chamber 28 can be released.

A piston rod 19 is connected to the upper end of the valve case 35 via a connecting shaft 41 and a universal joint 42. This connecting shaft 41 is formed hollow, and has a plurality of long holes 43 on its circumferential surface.
is formed, and the adjustment screw 39 can be adjusted through this elongated hole 43.

A second valve mechanism 50 is attached to the cap 23 at the lower end of the cylinder 21. The second valve mechanism 50 includes a casing 51, and the inside of the casing 51 is divided into three chambers 54A, 54B, and 54C by two diaphragms 52 and 53, and the central chamber 54B is provided in the cap 23. The through hole 23A communicates with the damper chamber 28, the left chamber 54A communicates with a pressure fluid supply mechanism 62 such as a compressor via a pressure reducing valve 61 and is used as a high pressure section, and the right chamber 54C communicates with the casing 51. It is communicated with the atmosphere through the small hole 51A, so that the pressure in the right chamber 54C does not change even when the diaphragm 53 is displaced.

A valve body 55 having a through hole 55A is fixed to the center of the one diaphragm 52, and
A spring receiver 56 is fixed to the center of the other diaphragm 53 , and a compression spring 57 as a biasing means is interposed between the spring receiver 56 and one diaphragm 52 .
Valve seat 5 made of rubber, synthetic resin, etc. fixed to
8. At this time, the valve body 5
5 and the valve seat 58 by adjusting the spring 57.
Alternatively, the valve body 55 is not completely moved by the valve seat 58 by providing a groove or the like in the contact portion of both members, or by providing a stopper that restricts the movement of the valve body 55 toward the valve seat 58 by more than a predetermined amount. As a result, the pressure fluid (compressed air) from the pressure fluid supply mechanism 62 is always supplied to the central chamber 54B, that is, the damper chamber 28 while being throttled by the valve body 55. ing. Further, an adjusting screw 59 screwed into the casing 51 and serving as an adjusting means is brought into contact with the spring receiver 56.
9, the operating pressure of the valve body 55 can be adjusted.

Next, the operation of this embodiment will be explained.

When gripping the sliding shaft 11 and moving the sliding shaft 11 up and down toward the point to be measured on the object to be measured (not shown),
This movement includes the extension rod 17, the connecting rod 18, the piston rod 19, the connecting shaft 41, and the valve case 35.
is transmitted to the piston 24 via.

On the other hand, pressure fluid at a predetermined pressure is supplied into the damper chamber 28 from the pressure fluid supply mechanism 62 via the second valve mechanism 50, and in a normal state, the valve body 33 of the first valve mechanism 30 and the second The valve body 5 of the valve mechanism 50 of
5 is in a nearly closed state, the inside of the damper chamber 28 is maintained at a predetermined pressure, and the force in the direction of pushing up the piston, which is generated by the product of this pressure and the pressure-receiving area of the piston 24, is applied to the sliding shaft 11 and the sliding shaft 11. Since the weight of each member connecting the moving shaft 11 and the piston 24 is matched, the weight of the sliding shaft 11, etc. is balanced by the balance device 20, and its movement is extremely light. At this time, when the sliding shaft 11 descends, that is, when the piston 24 descends, the pressure in the damper chamber 28 tends to increase, but this pressure increase causes a pressure difference between the damper chamber 28 and the inside of the valve case 35. As the diaphragm 34 of the first valve mechanism 30 increases in size, the diaphragm 34 of the first valve mechanism 30 is raised against the compression spring 38, so the opening degree between the valve body 33 and the valve seat 31 becomes large, and the pressure fluid in the damper chamber 28 is released from the valve body. 2
The damper chamber 28 is discharged to the atmosphere as a low pressure section through the through hole 27 of the valve body 33, the through hole 32 of the valve body 33, and the through hole 36 of the valve case 35, and the inside of the damper chamber 28 is maintained at a predetermined pressure. Further, when the sliding shaft 11 rises, that is, when the piston 24 rises, the pressure in the damper chamber 28 tends to decrease, but this pressure decrease causes the damper chamber 28, that is, the casing 51
As the pressure difference between the central chamber 54B and the left chamber 54A increases, the left diaphragm 52 of the second valve mechanism 50 is moved to the right against the compression spring 57. The opening degree between the valve seat 58 and the valve seat 58 increases, and the pressure fluid generated by the pressure fluid supply mechanism 62 flows into the pressure reducing valve 61, the left chamber 54A, the through hole 55A of the valve body 55, the center chamber 54B, and the cap 23. A larger amount is supplied into the damper chamber 28 through the through hole 23A, and the inside of the damper chamber 28 is maintained at a predetermined pressure.

In this way, the inside of the damper chamber 28 is always kept at a substantially constant pressure regardless of the movement of the sliding shaft 11, so the sliding shaft 11 can be operated with almost no operating force required. .

According to this embodiment as described above, when the sliding shaft 11 is lowered, the resulting pressure difference opens the valve body 33, and the fluid in the damper chamber 28 is discharged through the through hole 32 to the low pressure side. On the other hand, when the sliding shaft 11 is raised, the resulting pressure difference opens the valve body 55, and the pressure fluid supply mechanism 62
The fluid is discharged to the damper chamber 28 side through the through hole 55A. Therefore, unless the sliding shaft 11 is lowered, the fluid in the damper chamber 28 will not be released to the low pressure section and will continue to be maintained, so even if the fluid supply is stopped due to a failure of the pressure fluid supply mechanism 62, etc., the sliding The moving shaft 11 will not fall.

In addition, since the weight of the sliding shaft 11, etc. is balanced by the pressure fluid in the damper chamber 28 instead of the weight, the weight of the balance device 20 can be significantly reduced, which allows the weight of the crossbeam 6, etc. to be balanced by the measuring machine side. load can be reduced, measurement errors due to bending of the crossbeam 6, etc. can be reduced, and measurement accuracy can be improved. Furthermore, since wire winding pulleys and the like are not required, the height of the device can be reduced accordingly, and the measuring device can be made smaller. Moreover, the first valve mechanism 30 has a second valve mechanism on the piston 24 side.
Since the valve mechanisms 50 are respectively provided on the cylinder 21 side, the valve mechanism 50 is compact as a whole.

In addition, since the operating pressure of the first and second valve mechanisms 30 and 50 can be easily adjusted using the adjustment screws 39 and 59, it is possible to easily cope with changes in weight due to replacement of the probe 12, and the sliding shaft Even though the opposite directions of upward acceleration and downward acceleration occur during the upward and downward operations of 11, the operating forces for both can be set equally, so the operation of the sliding shaft 11 can always be carried out easily. It can be carried out.

Moreover, the pressure fluid (compressed air) in the damper chamber 28 is supplied to the sliding surface between the piston 24 and the cylinder 21 through the small hole 29, and the so-called fluid (air)
Since it acts as a bearing, this also causes the sliding shaft 1 to
1. Operation force can be reduced. Furthermore, the piston 24
Since the piston rod 19 and the piston rod 19 are connected via the universal joint 42, the sliding shaft 1
1 can be transmitted to the piston 24 in a stable manner at all times. Further, the first and second valve mechanisms 30,
Since the valve bodies 33 and 55 of No. 50 are not completely closed, and the pressure fluid in the damper chamber 28 is always allowed to flow, the valve bodies 33 and 55 are analog type in which the degree of opening changes. control, and the operation of the piston 24 can be made smoother.

In addition, in implementation, the casing 51 of the second valve mechanism 50 may be formed integrally with the cylindrical body 22 of the cylinder 21, and in this way, the diaphragm 5
There is an advantage that step 3 can be omitted. Further, the valve bodies 33 and 55 of the first and second valve mechanisms 30 and 50 may be configured to be completely closed when not in operation, but as in the embodiment described above, the pressure inside the damper chamber 28 is always maintained. If the fluid is supplied and discharged, there is an advantage that the piston 24 can operate more smoothly as described above. Furthermore, the first and second valve mechanisms 30 and 50 are not limited to structures using diaphragms 34 and 52;
A check valve or the like using a ball or the like may be used. In short, the first valve mechanism 30 is actuated by the difference between the pressure in the damper chamber 28 and the pressure in a low pressure part such as the atmosphere, and the pressure in the damper chamber 28 is Any mechanism that can discharge fluid may be used, and the second valve mechanism 50 is connected to the damper chamber 28.
Damper chamber 28
Any mechanism that can supply pressurized fluid to the inside may be used. Furthermore, the present invention is applicable not only to three-dimensional measuring machines but also to other general measuring machines.

As described above, according to the present invention, the following effects can be achieved.

According to the first invention, there is provided a valve body that closes a through hole that communicates a damper chamber defined by a cylinder and a piston with a low pressure region such as the atmosphere, and when the movable detection part is lowered, A first valve mechanism that opens the valve body due to the pressure difference generated and releases the fluid in the damper chamber to the low-pressure part side through the through hole communicates with the high-pressure part side that communicates with the damper chamber and the pressure fluid supply mechanism. The valve body has a valve body that closes the through hole, and when the movable detection part is raised, the valve body is opened by the pressure difference generated thereby, and the fluid of the pressure fluid supply mechanism is discharged through the through hole to the damper chamber side. Since the structure is equipped with the second valve mechanism, when the movable detection part is lowered, the resulting pressure difference opens the valve body, and the fluid in the damper chamber is released through the through hole to the low pressure part side. When the movable detection section is raised, the resulting pressure difference opens the valve body, and the fluid from the pressure fluid supply mechanism is discharged through the through hole toward the damper chamber. Therefore, unless the movable detection part is lowered, the fluid in the damper chamber will not be released to the low pressure part side and will continue to be maintained, so even if the fluid supply is stopped due to a malfunction of the pressure fluid supply mechanism, the movable detection part will not fall. It has the effect of preventing

Moreover, the first and second valve mechanisms may each include a biasing means for biasing the valve body in a direction to close the through hole, and an adjusting means for adjusting the biasing force of the biasing means. For example, even though the upward and downward accelerations occur in opposite directions when the movable detection section is operated up and down, the operating forces for both operations can be set equally.

According to the second invention, in addition to the first valve mechanism and the second valve mechanism, the piston has a small hole that is opened in the circumferential surface of the piston and communicates with the damper chamber. Since the structure is equipped with a fluid bearing that supplies both bodies in the damper chamber to the sliding surfaces of the piston and cylinder through the holes, the fluid in the damper chamber is supplied to the sliding surfaces of the piston and cylinder through the small holes. Therefore, in addition to the above effects, the frictional resistance on the sliding surface between the piston and cylinder can be reduced without using any special equipment, and the movable detection part can move up and down smoothly. There is.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example in which a conventional balance device is applied to a coordinate measuring machine, FIG. 2 is a cross-sectional view showing an example in which a balance device according to the present invention is applied to a coordinate measuring machine, and FIG. The figure is an enlarged sectional view of one embodiment of the balance device of the present invention. 11...Sliding shaft as a movable detection part, 20...
Balance device, 21... cylinder, 24... piston, 28... damper chamber, 29... small hole, 30...
...first valve mechanism, 31...valve seat, 33...valve body,
34...Diaphragm, 38...Compression spring, 39
... Adjustment screw, 50 ... Second valve mechanism, 52 ...
Diaphragm, 55... Valve body, 57... Compression spring, 58... Valve seat, 59... Adjustment screw, 62...
Pressure fluid supply mechanism.

Claims (1)

[Scope of Claims] 1. A measuring device including a cylinder, a piston connected to a movable detection part of the measuring device and slidable within the cylinder, and a damper chamber defined by the piston and the cylinder. The balance device has a valve body that is attached to the piston and closes a through hole that communicates the damper chamber with a low-pressure region such as the atmosphere, and when the movable detection part is lowered, the pressure generated by the valve body is fixed to the piston. A first valve mechanism that opens the valve body based on the difference and releases the fluid in the damper chamber to the low pressure side through the through hole, and pressurizes the fluid in the damper chamber with a pressure that balances the weight of the movable parts such as the movable detection part and the cylinder. a pressure fluid supply mechanism that communicates with the high pressure section, and a valve body that is attached to the cylinder and that closes a through hole that communicates between the damper chamber and the high pressure section side that communicates with the pressure fluid supply mechanism; When the movable detection part is raised, the valve body is opened by the pressure difference generated thereby, and the fluid of the pressure fluid supply mechanism is discharged to the damper chamber side through the through hole. A balance device for a measuring machine, characterized in that the valve mechanism and the second valve mechanism are configured so as not to be completely closed. 2. In claim 1, the first valve mechanism and the second valve mechanism include a biasing means for biasing the valve body in a direction to close the through hole, and a biasing means for biasing the valve body in a direction to close the through hole. A balance device for a measuring machine, characterized in that each device includes adjustment means for adjusting a biasing force. 3. A balance device for a measuring machine including a cylinder, a piston connected to a movable detection part of the measuring machine and slidable within the cylinder, and a damper chamber defined by the piston and the cylinder, It has a valve body that is attached to the piston and closes a through hole that communicates between the damper chamber and a low pressure region such as the atmosphere, and when the movable detection part is lowered, the valve body is opened by the pressure difference generated thereby. a first valve mechanism that discharges the fluid in the damper chamber to the low pressure section through the through hole; and a first valve mechanism that communicates with the high pressure section so as to pressurize the fluid in the damper chamber at a pressure that balances the weight of the movable sections such as the movable detection section and the cylinder. a pressure fluid supply mechanism that is attached to the cylinder and that closes a through hole that communicates between the damper chamber and a high pressure section side that is communicated with the pressure fluid supply mechanism, a second valve mechanism that opens on the circumferential surface of the piston and opens the valve body due to the pressure difference generated thereby, and releases the fluid of the pressure fluid supply mechanism to the damper chamber side through the through hole; and a fluid bearing having a small hole communicating with the damper chamber and supplying the fluid in the damper chamber to the sliding surface of the piston and the cylinder through the small hole, and a first valve mechanism and a second valve mechanism. A balance device for a measuring machine, characterized in that the valve mechanism is configured so as not to be completely closed.