JP2008183699A - Contact type position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a failure cannot be avoided because a clearance between a movable part and a fixed part cannot be reduced in a conventional protection structure when using a contact type position sensor in a machine tool in a bad environment with splashing coolant and chips. <P>SOLUTION: In this position sensor, a movable member burying the clearance between a fixed protective ring and a movable protective cover is provided and the movable member is slid by following the movement of the protective cover by being energized by a spring, thereby minimizing the clearance and preventing the failure. The spring has a larger outer diameter than that of a return spring of a conventional measuring shaft, and thereby the spring reduces inclination of a large diameter contact and can be useful for improving accuracy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a contact-type position sensor.

  Conventionally, when a contact-type position sensor is mounted on a machine tool that is subject to coolant or chips, the periphery of the measuring shaft is covered with a stretchable protective boot, and the boot is damaged by chips with the protective ring and protective cover. It was prevented.

A conventional contact type position sensor will be described below.
FIG. 3 shows an example of an overall view. The case 11 may have any shape such as a square or a round cylinder. Reference numeral 12 denotes a tip portion having a contact 13 at the tip, 14 denotes a protective ring, 15 denotes a protective cover, and 16 denotes a cord. In FIG. 3, the measuring shaft 17 protruding from one surface of the main body case 11 is coupled to the distal end portion 12, is fitted into the bearing 18 and is urged by a spring 19, and is always fixed by an internal stopper (not shown). Has stopped. When the detection body 20 pushes the contact 13, the sensor portion (not shown) in the case 11 is operated by the other end of the measurement shaft 17, an ON / OFF signal is transmitted, and is transmitted to the external circuit by the code 16. In the case of a machine tool, the detection body 20 is a drill, a cutter, an end mill, or the like.

The periphery of the measuring shaft 17 is protected by a protective boot 21 with good flexibility so that the coolant does not enter the inside. Further, there is a protective cover 15 attached to the protective ring 14 and the tip 12 so that the protective boot 21 is not damaged by the chips, so that the protective cover 15 does not interfere with the movement of the protective cover 15 and the scattered chips do not hit the protective boot 21 directly. Some overlap. However, the clearance 22 cannot be reduced too much in consideration of the concentricity error of the moving protective cover 15, the fluctuation of the movement, the inclination due to the direct hit of the coolant, and the like.
"Metrole Position Sensor Dimension Identification Sensor Catalog 2004" Metrol Co., Ltd.

  Recently, sintered metal is often cut by machine tool processing, and the chips become finer in the shape of sand. When entering a slight gap, the protective boot 21 is broken, and the coolant enters the case from the damaged portion, and the measuring shaft In many cases, malfunctions and sensor signal accidents occurred.

  The present invention is intended to solve the problems of such a conventional structure, and an object of the present invention is to realize the prevention of failure by extremely reducing the clearance 22 between the protective ring 14 and the protective cover 15. Is.

  In order to achieve the above object, the present invention is provided with a movable member that extremely reduces the clearance between the protective ring and the protective cover, and a spring that is urged to follow the movement of the protective cover.

  Further, a seal member is provided on the movable member so as to further eliminate the gap and improve the waterproof property. (Claim 2)

  As described above, the contact type position sensor according to the present invention prevents the coolant and chips from entering the clearance between the protective ring and the protective cover, thereby preventing the malfunction of the measuring shaft and the signal failure of the sensor. A sensor can be provided.

  In addition, when using for a machine tool and a detection body is an end mill, the contact with a large outer diameter is increasing. In that case, the contact surface is required to be parallel to the attachment reference surface. At this time, the spring that applies the contact force (return force) to the measurement shaft is the large-diameter spring of the present invention. In addition, the protective cover can be attached and detached with a retaining ring, so that the contact force can be easily changed later.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a movable member located on the upper end surface of the protective ring 14, and the outer diameter is fitted to the inner diameter of the protective cover 15 with a very small clearance. The spring 2 is located inside the protective cover 15 and urges the movable member 1 to follow the movement of the protective cover 15 so that the end surface of the protective ring 14 can slide smoothly.

  Since the spring 2 has a larger diameter than that of the spring 19 in FIG. 3, when the contact 13 has a large diameter, there is an effect that the inclination of the contact when the periphery is pushed can be reduced. In some cases, the spring 19 can be omitted.

  FIG. 2 shows a structure in which a seal member 3 is provided on the outer periphery of the movable member 1 to improve waterproofness.

Sectional drawing of the contact-type position sensor which shows embodiment of this invention The movable member part diagram of claim 2 Sectional view of a conventional contact-type position sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable member 2 Spring 3 Seal member 11 Case 12 Tip part 13 Contact 14 Protective ring 15 Protective cover 16 Code 17 Measuring shaft 18 Bearing 19 Spring 20 Detector 21 Protective boot 22 Clearance

Claims (2)

    Cover the periphery of the measurement shaft that protrudes from one side of the main body case and has a contact at the tip with elastic boots. Further, the fixed protection ring raised from the one surface and the protective cover attached to the measurement shaft In a contact-type position sensor that prevents damage to the boot, the movable member is located on the upper end surface of the protective ring and the outer periphery is fitted inside the protective cover, and the movable member is in contact with the upper end surface of the protective ring. A contact-type position sensor with a large-diameter spring biased to slide inside the protective cover.   The contact-type position sensor according to claim 1, wherein a seal member is provided on an outer periphery of the movable member.

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