JPH0239206Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a touch sensor used in a coordinate measuring machine or a machine tool.

(Background of the invention) This type of touch sensor uses a detector installed in the main body housing to detect the displacement caused when the contact of a movable body supported by the main body housing so as to be able to be displaced three-dimensionally comes into contact with the object to be measured. It is configured to detect and obtain a touch signal. In order to improve the repeatability of returning the contact to its home position, the upper fulcrum of the probe is formed inside the main body housing, and a fixing point is provided in the main housing between the upper fulcrum and the tip of the probe. A touch sensor has been proposed in Japanese Utility Model Application No. 58-34004, in which a detector is formed by a contact and a movable contact provided on a probe to cooperate with the contact.

The proposed upper fulcrum is formed by a cantilevered leaf spring supported by the main body housing and a guide member disposed on the leaf spring.
Therefore, it becomes difficult to maintain a constant position of the central axis of the guide member. That is, compared to when the leaf spring is in a horizontal state, when the leaf spring is bent, the central axis moves in the direction in which the leaf spring is fixed. As a result, the probe guided by the guide member is tilted. Therefore, in order to reduce bending, a leaf spring that is sufficiently rigid must be used. However, if the rigidity is increased too much, the contact of the electrical contact as a detector becomes unstable. In addition, the axial direction of the probe is regulated by an annular inclined surface formed on the main body housing that also serves as a fixed contact, and a spherical body that is a movable contact that comes into contact with this, resulting in poor reproducibility of returning to a fixed position in the axial direction. There was a drawback.

(Purpose of the invention) The purpose of the present invention is to solve these drawbacks, improve the reproducibility of returning the probe to its home position in any direction, and provide a probe with a small measuring force.

(Embodiment) FIG. 1 is a sectional view of an embodiment of the touch sensor of the present invention.

The movable body 2 has a contactor 3 at the lower end of a shaft 4.
It has a sphere 6 at its upper end, and a disk 5 is fixed above the sphere 6. The disc 5 has a total of three hemispherical contact pieces 9 at approximately 120 degree intervals on its lower surface, and these contact pieces 9 are connected to ring-shaped standards formed on the upper surface of the flange 7 formed on the fixed housing 1. It is placed on surface 8. The three contact pieces 9 are configured as movable contacts, and the ring-shaped reference surface 8 is also configured as a fixed contact. A pressure spring 10 is disposed between the adjustment screw 11 of the fixed housing 1 and the top surface of the disc 5 so that the contact piece 9 always comes into contact with the reference surface 8 when the movable body 2 is free. . Further, a positioning seat 12 having a downwardly converging surface is fitted into the sphere 6 from below, and positions the axis of the measuring element 2.

The positioning seat 12 can be moved in parallel only in the axial direction of the movable body 2 by a disc-shaped diaphragm 13. The diaphragm 13 is fixed to the fixed housing 1 so as to generate a force that pushes the sphere 6 upward. The positioning seat 12 and the diaphragm 13 are attached to and detached from the fixed housing 1 by means of a screw ring 14.
At this time, the adjustment screw 11 is used to adjust the downward force exerted by the pressing spring 10 to be greater than the upward force exerted by the diaphragm 13.

With the above configuration, the position of the contact 3 is always at 1.
It is designed to be stable in one position.

When the touch sensor shown in FIG. 1 is used in a coordinate measuring machine or the like, the fixed housing 1 is attached to a moving table of the coordinate measuring machine, and the contact 3 is brought into contact with the object to be measured from the side. The moment it makes contact, the probe 2 rotates around the sphere 6 as the center of rotation. This instantaneous reference plane 8
The contact at any one of the three contact points between the contact piece 9 and the contact piece 9 is released. Even when the contactor 3 is brought into contact with the object to be measured from the axial direction, the contact between the reference surface 8 and the contact piece 9 is released. Since the release of contact between the reference surface 8 and the contact piece 9 at this time is detected by electrical non-conduction, the contact between the contact piece 3 and the object to be measured can be detected. When the contact with the object to be measured is released, the contactor 3 returns to its original position due to the urging force of the pressure spring 10 and the diaphragm 13, and electrical continuity is established.

Because of this structure, in this embodiment, even if the movable table moves further after the contactor 3 contacts the object to be measured, it can escape safely, and prevents the structure from being subjected to excessive stress and breaking. Never.

Then, when the contact between the contact and the object to be measured is released, the contact returns to its original position, so that high-precision measurements can be performed continuously. Furthermore, during measurement, the measuring force applied to the object to be measured is required to be as small as possible, but the difference between the pressing force by the pressing spring 10 and the pushing up force by the diaphragm 13 is made small (the pressing spring 10 is larger). ), the measuring force can be reduced. That is, the contact piece 9 is urged toward the reference surface by the force of the difference, but by reducing this force, the force (measuring force) required to move the contactor 3 can be reduced.

FIG. 2 shows the structure of the reference surface and contact piece in another embodiment. FIG. 3 is a view taken along the arrows in FIG. In other words, the reference plane consists of two reference pieces 15 and 16.
The contact piece is a spherical seat. It is sufficient to use this structure for any one of the three contact pieces. This structure prevents the movable body 2 from rotating in a plane perpendicular to the axis. Although not shown, the sphere 6 is replaced with a conical part, one V-shaped groove radiating in the radial direction is provided on this conical slope, and the positioning seat 12 is provided with a spherical seat that fits into this V-shaped groove. Rotation of the movable body around the axis can be prevented even if the movable body is rotated around the axis.

(Effects of the invention) As described above, according to the invention, the return position repeatability of the contact is good and the measuring force can be reduced, so it can be used as a touch sensor for coordinate measuring machines and machine tools. It is valid.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the device according to the present invention;
FIG. 2 is an enlarged view of another embodiment of the contact piece and reference surface;
FIG. 3 is a view taken along the arrows in FIG. Explanation of symbols of main parts, 1... Fixed housing, 2... Movable body, 3... Contact, 6... Sphere,
8... Reference surface, 9... Contact piece, 10... Pressing spring, 12... Positioning seat, 13... Diaphragm.

Claims (1)

[Claims for Utility Model Registration] (1) Comprising a fixed housing and a movable body having a contact for detecting a measurement target, the fixed housing forming a reference surface that restricts downward movement of the movable body. The movable body is provided with at least three contact members near its upper end that contact the reference surface from above, and the movable body is connected to the reference surface by a spring means disposed between the movable body and the fixed housing. The movable body further has a positioning portion formed therein, a positioning seat for supporting the positioning portion from below, and the positioning seat is connected to the reference surface. connected to the fixed housing by a connecting spring means that presses at least one contact member in a direction to break contact, the spring force of the connecting spring means acting in a direction opposite to the force of the pressing spring;
A touch sensor characterized in that the force is smaller than the force of the pressing spring. (2) The reference surface that comes into contact with any one of the contact members has a V-shaped converging surface, and the contact member that comes into contact with this reference surface is a spherical seat that fits into the V-shaped convergent surface. A touch sensor according to claim (1) of the utility model registration claim, which is characterized in that: