JPH0370763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring instrument, and more particularly to a balance device that reduces the operating force of a probe.

For example, in a coordinate measuring machine, a horizontal beam is moved in the front-rear direction (Y-axis direction) of the surface plate via supports on both sides of the surface plate, and a slider is moved along the horizontal beam in the left-right direction (X-axis direction) of the surface plate. ), a probe shaft is provided on the slider so as to be movable in the vertical direction (Z-axis direction) of the surface plate, and by movement in these X, Y, and Z-axis directions, the probe attached to the lower end of the probe shaft is covered. The device is moved in a three-dimensional direction while successively contacting the object to be measured, and the dimensions, shape, etc. of the object to be measured are measured. A structure like this is
During measurement, when moving the probe shaft while grasping its lower end, the weight of the probe shaft becomes a major operational obstacle.

Therefore, in conventional measuring machines, one end of a wire is connected to the upper end of the probe shaft, the other end of this wire is connected to a weight through a pulley, and the weights of this weight and the probe shaft are balanced against each other. It used a counterweight method. However, in this counterweight method, in addition to the weight of the weight that balances the weight of the probe shaft,
Since the weight of the pulley, cover, etc. is added to the horizontal beam via the slider, the horizontal beam is deflected, which is a factor that adversely affects measurement accuracy. Therefore, as a countermeasure for this point, increasing the size of the structure can prevent a decrease in accuracy, but on the other hand, high-speed measurement cannot be expected due to the increase in the weight of each member.

On the other hand, in order to solve the drawbacks of the counterweight method, the probe shaft and the air cylinder are connected to each other via a rope or a link, and the weight of the probe shaft is balanced by the air pressure of the air cylinder. , the so-called air cylinder method was developed. However, even with this method, since the cylinder is provided separately from the probe shaft, the overall size increases, and as a result, considering the weight of the cover and mounting components, it is difficult to expect a significant reduction in overall weight. Ta.

An object of the present invention is to provide a balance device for a measuring machine that solves the drawbacks of both of these types and can be made smaller and lighter.

Therefore, in the present invention, a hollow shaft member with a measuring element attached to the lower end is provided in the structure so as to be movable in the vertical direction, and a cylinder device consisting of a cylinder, a piston, and a piston rod is inserted and inserted into the inside of this shaft member. , a pressure adjustment unit that integrally connects the cylinder and the shaft member, supports the upper end of the piston rod on the structure, and controls the pressure inside the cylinder at a constant level with respect to the vertical movement of the shaft member. By providing a device, that is, a cylinder device that balances the weight of the shaft material etc. by the pressure inside the cylinder, inside the shaft material to which the measuring head is attached, the overall size and weight can be reduced, and the above-mentioned It is an attempt to achieve a goal.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows the external appearance of the three-dimensional measuring machine of this embodiment. In this three-dimensional measuring machine, a horizontal beam 3 is sent to the slider 4 along the horizontal beam 3 in the front-rear direction (Y-axis direction) of the surface plate 1 via supports 2A and 2B provided on both sides of the surface plate 1. is provided to be movable in the horizontal direction (X-axis direction) of the surface plate 1, and a probe shaft 6 having a probe 5 at the lower end of the slider 4 is movable in the vertical direction (Z-axis direction) of the surface plate 1, In other words, the measuring element 5 is provided so as to be movable in three-dimensional directions via these structures. Furthermore, when the measuring stylus 5 is moved in a three-dimensional direction and comes into contact with the object to be measured placed on the surface plate 1, the position of the horizontal beam 3 in the Y-axis direction and the position of the slider 4 in the X-axis direction are changed. and the position of the probe shaft 6 in the Z-axis direction are each detected by a detector (not shown) and then displayed on a display or the like.

FIG. 2 shows the internal structure of the probe shaft 6. In the probe shaft 6, a prismatic shaft member 13 having a circular hollow hole 12 toward the central axis is attached to a holding frame 11 that is integrally formed at upper and lower positions on the front surface of the slider 4, and is movable up and down, that is, on a Z-axis. It is held so that it can move freely in any direction. Shaft material 13 and the holding frame 11
As shown in FIG.
Air pads 14 that eject compressed air to the two outer surfaces are each held via bolts 15. Further, the shaft member 13 is provided with a holder 16 at its lower end for attaching the measuring element 5, and a cylinder device 17 is provided inside the hollow hole 12.
is inserted.

The cylinder device 17 includes a cylinder 19 that is fitted into the hollow hole 12 of the shaft member 13 and integrally connected to the shaft member 13 via a connecting plate 18, and a cylinder 19 that is slidable inside the cylinder 19. The fitted piston 21, the cylinder head 20 fitted to the upper end of the cylinder 19, and the cylinder head 2
The piston rod 22 passes through the center of the piston 2 and has a lower end connected to the piston 21. The upper end of the piston rod 22 is inserted into the insertion hole 24 of the bracket 23 fixed to the slider 4.
It projects upward through the. Bracket 23
A collar plate 26, which is supported on the upper surface of a bracket 23 via a bearing 25, is fixed to the end of the piston rod 22 that projects upwardly by a nut 27. That is, the upper end of the piston rod 22 is supported by the bracket 23 so as to be movable in the radial direction of the cylinder 19. Further, an air supply hole 28 is bored in the cylinder head 20, and a pressure regulator 3 is connected to the air supply hole 28 via a pipe 29 to maintain the pressure of the cylinder device 17 at a constant pressure.
0 is connected.

As shown in FIG. 4, the pressure regulator 30 is configured such that air at a constant pressure, for example 5 kg/cm ² , supplied from a pressure source 31 is applied to a first regulator 34 through an air filter 32 and a micro-mist separator 33. ing. The first regulator 34 has a secondary side connected to the air pad 14 and the second
The pressure on the secondary side thereof is maintained at a set pressure of, for example, 4 kg/cm ² . Second regulator 35
The secondary side is connected to the inside of the cylinder 19, and like the first regulator 31, the pressure on the secondary side, that is, the pressure inside the cylinder 19, is set to a set pressure, for example, 1.7.
It is designed to be maintained at Kg/cm ² .

Incidentally, the functions of the first regulator 34 and the second regulator 35 will be briefly explained with reference to FIG. 5. Now, when the setting screw 41 is completely loosened, the main valve 42 is closed, so the air pressure supplied to the air supply port 43 does not flow to the exhaust port 44, and a part of it flows into the flow path 45.
from the first diaphragm 4 through the fixed diaphragm 46
The air flows into the upper chamber 48 partitioned by the arrow 7 and forms a nozzle back pressure, but since the flapper 50 is open, it is discharged from the nozzle 51 through the flow path 52 to the atmosphere.

Here, when the setting screw 41 is rotated and the setting spring 53 is compressed, the setting spring 53
The compressive force causes the flapper 50 to close the nozzle 51 via the second diaphragm 54 and the third diaphragm 55. Then, the nozzle back pressure increases and the first diaphragm 47 is pushed down, which opens the main valve 42 via the valve rod 56. As a result, the air pressure supplied to the air supply port 43 is transferred to the exhaust port. Flows to 44. Exhaust port 44
The air pressure flowing into the second diaphragm 49 flows through the flow path 57 into the lower chamber 49 partitioned by the first diaphragm 47, is balanced with the nozzle back pressure in the upper chamber 48, and further flows from the flow path 58 into the second diaphragm 49. It flows into a feedback chamber 59 partitioned by a third diaphragm 54 and a third diaphragm 55, and is balanced with the compression force of the setting spring 53.

In this state, if the air pressure in the exhaust port 44 rises too much, the second diaphragm 54 is pushed up as the pressure in the feedback chamber 59 rises, and the nozzle 51 is opened by the rise of the flapper 50. Then, since the nozzle back pressure decreases, the first diaphragm 47 is pushed up, and as a result, the main valve 42 closes and at the same time the escape hole 60 is opened and excess air is released into the atmosphere. Conversely, when the air pressure at the exhaust port 44 decreases, the setting spring 53
The compressive force of the second diaphragm 54 and the third
The nozzle 51 is closed via the diaphragm 55. Then, the nozzle back pressure increases, so
The first diaphragm 47 is pushed down, which opens the main valve 42 and allows air to flow from the air supply port 43 to the exhaust port 44 . In this way, the regulator shown in FIG. 5 responds sensitively to pressure fluctuations on the secondary side and functions to always maintain the secondary side pressure constant relative to the set pressure.

Next, the operation of this embodiment will be explained. During measurement, the lower end of the probe shaft 6 is held in the hand and the probe 5 is moved in three-dimensional directions to successively contact the object to be measured. Then, the contact point 5 touches the object to be measured,
After the positions in the Y and Z axis directions are detected by detectors (not shown), they are displayed on a display or the like.

Now, when the shaft member 13 is raised while air pressure that balances the total weight of the shaft member 13, holder 16, gauge head 5, cylinder 19 and cylinder head 20 is being supplied to the cylinder 19, the volume inside the cylinder 19 will increase. increases, and its internal pressure begins to decrease. Then, when the secondary pressure falls below the set pressure due to a decrease in the internal pressure of the cylinder 19, the second regulator 35 operates in the direction of opening the main valve 42 based on the above-mentioned operation, thereby reducing the secondary pressure. In other words, the internal pressure of the cylinder 19 is maintained at the set pressure.

On the other hand, when the shaft member 13 is lowered from the balanced state, the volume inside the cylinder 19 decreases and its internal pressure begins to rise. Then, when the secondary side pressure rises above the set pressure, the second regulator 35 operates the main valve 42 in the direction of closing based on the above-mentioned operation, releases excess air to the outside through the escape hole 60, and closes the cylinder. 19 is maintained at the set pressure.

In this way, since the weight of each member constituting the probe shaft 6 is balanced by air pressure,
During measurement, the probe shaft 6 can be operated in the vertical direction with a relatively light force.

Therefore, according to this embodiment, since the weight of the shaft member 13 constituting the probe shaft 6 is balanced by the air pressure of the cylinder device 17, the weight can be reduced compared to the conventional counterweight system. Therefore, it is possible to increase the speed without adversely affecting measurement accuracy. In addition, since the cylinder device 17 is provided in the hollow hole 12 of the shaft member 13, the overall size can be reduced, and when considering the weight of the cover and mounting members, it is also lighter than the air cylinder method. can do.

In particular, in this embodiment, the air pressure of the cylinder device 17 is maintained constant by the second regulator 35, so when compared with the conventional air cylinder system, which constantly supplies air to the cylinder for balance. It has the advantage of excellent responsiveness to pressure fluctuations and no air consumption in a balanced state.

In addition, since the system is balanced by the air pressure of the cylinder device 17, even if measuring elements 5 of various shapes and weights are attached to the shaft member 13 depending on the measurement item, the measurement can be performed by adjusting the air pressure. It is possible to correspond to changes in the weight of the child 5.

Further, the cylinder 19 of the cylinder device 17 is integrated with the shaft member 13 via the connection plate 18, and the upper end of the piston rod 22 is attached to the bracket 23 attached to the slider 4 so that the cylinder 19 can be displaced in the radial direction. The piston rod 22 can be supported with the sliding surface of the shaft member 13 as a reference without hindering the vertical movement of the cylinder 19, and the assembly work at that time can be performed simply and easily.

In addition, since the shaft material 13 is square, the shaft material 1
3 does not rotate in the horizontal direction, and therefore the posture of the measuring stylus 5 can always be maintained at a constant posture. Furthermore, since the air pads 14 are provided on each surface of the shaft member 13, the shaft member 13 can be moved up and down smoothly.

In addition, in implementation, the piston rod 22 is
If the piston rod is made sufficiently thinner than the piston rod of a normal cylinder and has flexibility only in the radial direction of the cylinder 19, it can be equivalent even if there is no structure to support the piston rod so that it can move in the radial direction of the cylinder 19. This effect can be achieved.

Further, the pressure regulating device may use hydraulic pressure in addition to the one that uses air pressure as described in the above embodiment.

On the other hand, in the above embodiment, the probe axis of a three-dimensional measuring machine was targeted, but the present invention can be applied to other equipment than the above-mentioned three-dimensional measuring machine as long as it has an axis that moves up and down. The probe may be automatically driven according to a predetermined procedure.

As described above, according to the present invention, it is possible to provide a balance device for a measuring machine that is lightweight and can be downsized.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a coordinate measuring machine showing an embodiment of the present invention, Fig. 2 is a sectional view showing the internal structure of the probe shaft, Fig. 3 is a sectional view taken along the - line in Fig. 2, and Fig. 4 is a sectional view showing the internal structure of the probe shaft.
The figure is a circuit diagram showing the pressure regulating device, and FIG. 5 is a sectional view showing the internal structure of the regulator. 4...Slider as a structure, 13...Shaft member, 17...Cylinder device, 19...Cylinder,
21... Piston, 22... Piston rod, 3
0...Pressure adjustment device.

Claims (1)

[Scope of Claims] 1. A hollow shaft member with a measuring element attached to its lower end is provided in the structure so as to be movable in the vertical direction, and a cylinder device consisting of a cylinder, a piston, and a piston rod is fitted inside this shaft member. pressure that integrally connects the cylinder and the shaft member, supports the upper end of the piston rod on the structure, and adjusts the pressure within the cylinder to a constant level with respect to the vertical movement of the shaft member. A balance device for a measuring machine characterized by being equipped with an adjustment device. 2. In the balance device for a measuring machine according to claim 1, the upper end of the piston rod is
A balance device for a measuring machine, characterized in that the balance device is supported by the structure so as to be displaceable in the radial direction of the cylinder.