JPH0228402Y2 - - Google Patents

Description

[Detailed explanation of the invention] <Field of the invention> This invention can be attached to an NC machine tool such as a machining center or a measuring machine such as a coordinate measuring machine.
It relates to a touch sensor used to measure the dimensions and position of a workpiece or object to be measured.

<Prior art and its problems> Conventionally, as this type of touch sensor, a type in which a contact is displaced when it comes into contact with an object and a mechanical contact is opened/closed accordingly is known. ing. However, this type of touch sensor has a complicated structure, making it difficult and expensive to assemble, and the reliability of the sensor decreases over time due to wear and corrosion of the mechanical contacts. Ta.

In addition, as disclosed in Japanese Patent Application Laid-open No. 56-8502, the stress acting on a contactor that is displaced as it comes into contact with an object is transmitted to an electrical signal such as a voltage value through stress sensing means such as a piezoelectric element. Convert it to and sense it,
A device is known that is configured to output when the value of the electrical signal exceeds a predetermined value. However, with this type of touch sensor, components such as the contact, housing, and stress sensing means must be assembled with extremely high precision in order to prevent unexpected movement due to a small amount of external stress. This makes assembly difficult, and since the displacement stroke of the contact during sensor operation cannot be made large, the reliability of the sensor is not sufficient.

<Purpose of the invention> This invention was made in order to eliminate the above-mentioned drawbacks, and the object is to provide a touch sensor that has a simple structure, is easy to assemble, and can have a large displacement stroke and significantly improve reliability. The purpose is

<Description of Embodiments> FIG. 1 is a central sectional view of a touch sensor, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a sectional view taken along the - line in FIG. 1.

The conductive housing 21 is constructed by concentrically connecting a dish-shaped member 21a and a cylindrical member 21b. 22 indicates a connecting portion between the two. Hole 2 provided in the center of the dish-shaped member 21a
3 has a cylindrical insulating member 24 fitted therein. The cylindrical member 21b has two concentric stepped portions 25 and 26.
A tapered cylindrical elastic member 27 made of a conductive leaf spring or the like is concentrically protruded from one stepped portion 25. This elastic member 27 has a truncated conical portion having a plurality of slits cut out at equidistant intervals in the circumferential direction to form comb tooth portions 27a.

The contactor 28 includes an assembly part 28a that is assembled into the housing 21, a protrusion part 28b that projects outside the housing 21, and a flange part 28C that is formed at the boundary between these parts. The distal end of the assembly portion 28a is formed into a tapered surface 28d, and when the assembly portion 28a is assembled into the housing 21, the tapered surface 28d and the elastic member 28d are connected to each other.
A pressurized conductive rubber 29 in the shape of a truncated conical cylinder is incorporated between the comb tooth portions 27a of 7 and 7. As the pressurized conductive rubber 29, a material is used that has electrical conductivity when pressurized and does not have electrical conductivity when no pressure is applied. For example, an elastic material such as silicone rubber containing metal particles is used, and according to this, a thickness of 2
~ When using 3mm sheet material, from the natural state
When pressurized to 100g/ ^cm2 , its resistance value becomes 10MΩ.
It rapidly decreases from 1000Ω to less than several kilohms and becomes conductive. The response time at that time is fast, less than 1msec. In addition, the flange 28c of the contactor 28 and the cylindrical member 2
A biasing member 30 such as a compression spring is disposed between the stepped portion 26 and the other stepped portion 26 of the stepped portion 26, while a bearing member 3 is provided between the stepped portion 26 and the built-in portion 28a, respectively.
1a and 31b are provided. In this case, the bearing members 31a and 31b are made of an electrically insulating material with high hardness and excellent wear resistance, and are formed in an annular shape, and the outer peripheral surface of the bearing member 31b on the side of the built-in portion 28a is The bearing member 31a on the side of the stepped portion 26 has a tapered surface and is configured as a ring-shaped member with a square cross section. Therefore, as the contactor 28 is urged outward of the housing 21 by the urging member 30, the bearing members 31a and 31b are pressed against each other, whereby the contactor 28 is urged toward the outside of the housing 21. It will always remain in a fixed position in a stationary state. In addition,
Reference numerals 32 and 33 indicate electrical terminals provided on the contactor 28 and the dish-shaped member 21a, respectively, and these terminals 32 and 33 are connected by a lead wire 11 connected to an external load resistor 10. 12 in FIG. 1 is a power supply.

Next, the operation and effects of the above configuration will be explained.

When the contactor 28 is in a stationary state, the pressurized conductive rubber 29 is not pressurized, and the detection circuit of the touch sensor is in an OFF state. Further, as an object comes into contact with the protrusion 28b of the contactor 28 and an external force acts on it, the contactor 28 may, for example,
As shown by the imaginary lines in the figure, when the pressurized conductive rubber 29 is displaced in any three-dimensional direction, the pressurized conductive rubber 29 is pressurized between the elastic member 27 and the tapered surface 28d, and the pressurized conductive rubber 29 is It becomes conductive and the detection circuit of the touch sensor turns on. Further, the object moves away from the protrusion 28d and the contact 2
When the external force acting on 8 is removed, the contact 28 returns to its original resting state, as shown by the solid line in Figure 1, and the pressurized conductive rubber 29 becomes non-pressurized, and its conductivity is lost. The detection circuit of the touch sensor is then turned off.

As mentioned above, if the object
d, the characteristics of the pressurized conductive rubber 29 change between a state in which it does not conduct electricity and a state in which it conducts electricity, and the detection circuit of the touch sensor is controlled on and off.

Here, the pressurized conductive rubber 29 is connected to the contact 28.
The tapered surface 28d and the comb teeth portion 27 of the elastic member 27
Since the contactor 28 is held between
The displacement stroke during the operation of No. 8 becomes large.

<Structure and Effects of the Device> In this device, a pressurized conductive rubber that conducts electricity when pressurized and does not conduct electricity when it is not pressurized is pressurized with the displacement of a contact, and Since the pressurized state is released as the child returns to its normal position, no mechanical contacts are required and the structure is simplified. Moreover, since the pressurized conductive rubber is interposed between the tapered surface of the contact and the comb tooth portion of the tapered cylindrical elastic member, there will be some damage when assembling the pressurized conductive rubber, the contact, and the housing. Errors can be absorbed by the elastic displacement of the elastic member,
No unnecessary play is generated in the contacts while reducing their assembly accuracy. Further, by using an elastic member having a comb tooth portion, a large displacement stroke can be taken when the contactor is operated. Therefore, a touch sensor that is easy to assemble and has high reliability can be obtained at low cost. The touch sensor of this invention can be applied not only to machine tools and measuring machines, but also to various robots and limit switches.

[Brief explanation of the drawing]

FIG. 1 is a central sectional view of a touch sensor according to an embodiment of the invention, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a sectional view taken along the - line in FIG. 21... Housing, 27... Tapered cylindrical elastic member, 27a... Comb tooth portion, 28... Contact, 2
8d... Tapered surface, 29... Pressurized conductive rubber, 30
...Biasing member.

Claims (1)

[Scope of utility model registration request] a housing; a tapered cylindrical elastic member incorporated into the housing, the tapered cylindrical elastic member having a comb tooth portion formed by cutting a truncated conical portion at a distal end into slits at multiple locations in the circumferential direction; A contact element is installed in the housing concentrically with the member, and is interposed between the tapered surface of the tip of this contact element and the comb teeth of the tapered cylindrical elastic member, and provides electrical conductivity when pressurized. a pressurized conductive rubber that does not have electrical conductivity when not pressurized;
a biasing member for returning the contact to the home position, the pressurized conductive rubber is pressurized as the contact is displaced, and as the contact is returned to the home position; A touch sensor configured such that the pressurized state of the pressurized conductive rubber is released when the pressurized conductive rubber is pressed.