JPH01314903A - Two-finger type electric micrometer - Google Patents

Abstract

PURPOSE:To reduce cost and improve measurement accuracy by a method wherein relative movement of two contacts is converted into an electric amount by one position sensor so as to be detected. CONSTITUTION:One of arms 5a with contacts 7(7a, 7b) mounted is equipped with a position sensor 13 and the other 5b is provided with a sensor dog 15. With this sensor 13 and the sensor dog 15 facing via a narrow slit A, relative displacement of the two contacts 7a, 7b is detected by one sensor 13. The slit A is located at the vertex of an isosceles triangle whose base consists of a segment connecting a fulcrum Pa of the arm 5a and a fulcrum Pb of the arm 5b. While the size of a work 20 to be measured is measured as a sum of recession amount of the contacts 7a and 7b, variation of the slit A between the sensor 13 and the sensor dog 15 is proportional to the sum of recession amount of the contacts 7a and 7b, and this variation of the slit A is electrically converted and detected by the sensor 13.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electric micrometer that measures minute displacement by converting it into an electrical signal of an amount corresponding to the displacement, and uses two opposing contacts to This relates to an electric micrometer that measures the diameter and thickness of an object (to be measured) by holding it in between.

(Prior art) An electric micrometer has a structure that converts the amount of displacement of a contact into an electrical amount using a signal conversion element (for example, a differential transformer or a displacement sensor) and detects the amount of electricity. There are two types: a lever type with a contact at the tip of the plunger and a plunger type with a contact at the tip of the plunger. A two-finger electric micrometer, which is often used to measure the outside and inside diameters of turned objects, consists of two lever-type micrometers placed in a single case facing each other, each equipped with a contactor. The conventional type has a structure as shown in Fig. 2, with fingers protruding from the case.

In Fig. 2, 1 is a base, 2 and 3 are seats provided on the base, 4 is an L-shaped thin plate spring whose both ends are fixed to the seats 2.3,
5 is a swinging arm fixed to the corner part of the thin plate spring 4;
6 is a finger fixed to the tip of the swinging arm 5; 7 is a contact attached to the tip of the finger 6; and 8 is fixed to the base 1 to regulate the amount of movement of the base end of the swinging arm 5. The arm stopper 31 is a differential transformer interposed between the base l and the swing arm 5, and includes a first detection unit 32a with a suffix a added to the above reference numeral and a second detection unit 32b with a suffix suffix added. This is a structure in which the two are placed facing each other. Reference numeral 20 denotes a workpiece to be measured, and the contact portion C1 between the workpiece 20 and the contactor 7, the corner portion P of the spring 4 serving as the fulcrum of the swinging arm 5, and the detection portion S of the differential transformer 31 are arranged on the − straight line. ing. The detection signal of the differential transformer 31 is input to the arithmetic device 23 via the amplifier 21 and the linearizer 22, and the arithmetic device 23 calculates the diameter of the workpiece 20 from the differential amount between the differential transformers 31a and 31b.

This two-finger electric micrometer has six fingers.
When the contacts 7a and 7b attached to the tips of fingers 6a and 6b contact the workpiece 20 with the same contact pressure, the displacement of the differential amount between fingers 6a and 6b is detected, and since it is a differential, the micrometer body It has a feature that the measured value does not change even if the relative position between the contactor 7 and the workpiece deviates in the direction of movement of the contactor 7.

(Problems to be Solved by the Invention) However, the two-finger electric micrometer having the above structure has the following problems. First, two differential transformers are required to measure one location on the workpiece.
Two amplifiers and linearizers are required, which increases the cost. Second, measurement errors occur due to variations in the linearity of the two differential transformers and linearizers. Third, two amplifiers and linearizers are required, which causes measurement errors. Since the measurement errors of the detection unit are added, a resolution of less than half the minimum reading unit is required, which increases the cost of both the amplifier and the differential transformer.

The object of the present invention is to solve the above problems and provide a two-finger electric micrometer that is low in cost and has high measurement accuracy.

(Means for Solving the Problems) In order to solve the above problems, in the electric micrometer of the present invention, the position sensor 13 is mounted on one arm 5a on which the contactor 7 (7a, 7b) is mounted, and the position sensor 13 is mounted on the other arm 5b. Attach the sensor dog 15 to the position sensor 13 and sensor dog 1.
5 and facing each other through a narrow gap A, and the two contacts 7a
, 7b is adopted in which one displacement sensor 13 detects the relative displacement. By locating the gap A at the apex of an isosceles triangle whose base is the line segment connecting the fulcrum Pa of the arm 5a and the fulcrum Pb of the arm 5b, highly accurate position detection is possible.

(Function) The dimensions of the workpiece 20 to be measured are determined by the contactors 7a and 7.
According to the above structure, the amount of change in the gap A between the displacement sensor 13 and the sensor dog 15 is proportional to the sum of the retraction amounts of the contacts 7a and 7b. Since the amount of change in the gap A is converted into an electrical quantity by the displacement sensor 13, a change in the dimensions of the workpiece 20 can be measured with one sensor 13. and contacts 7a and 7b
Since the amount of change in is mechanically added and detected by the sensor 13, the sensor 13, the amplifier 2■, and the linearizer 22
Only one is required, and the accuracy of these devices only needs to meet the required minimum reading accuracy, and since no measurement errors are added, the achieved accuracy is also high.

(Embodiment) FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a base, 2 and 3 are seats, 4 is an L-shaped thin plate spring,
5 is a swinging arm, 6 is a finger, 7 is a contact, 8 is an arm stopper, 20 is a workpiece, C is a workpiece 20 and a contactor 7
P is the swinging fulcrum of the swinging arm 5, and among the above members, the members with the suffix a belong to the first detection unit 10a, and the members with the suffix belong to the second detection unit 10b. These members and their mutual relationships are the same as those of the conventional structure shown in FIG.

11 is a bracket fixed to the arm 5a, 12 is a sensor holder fixed to the tip of the bracket, 13 is a position sensor fixed to the sensor holder, 14 is a bracket fixed to the arm 5b, and 15 is formed at the tip of the bracket. This is a sensor dog.

The sensor dog 15, which is substantially integrated with the arm 5b, is attached to the leaf spring 4.
It rotates around a fulcrum Pb formed at the corner portion of b. Further, the arm 5a and the substantially body displacement sensor 13
is opposed to the sensor dog 15 through a slight gap A, and is a fulcrum Pa formed at the corner of the leaf spring 4a.
Rotates around the center. The swing angles of the arms 5a and 5b are limited by an arm stopper 8. The gap A between the sensor 13 and the sensor dog 15 is
It is located at the apex of an isosceles triangle whose base is a line segment connecting fulcrum Pa of arm 5b and fulcrum Pb of arm 5b. Thin spring 4
a, 4b are adjusted so that the measured pressure when the contacts 7a, 7b contact the workpiece 20 is a predetermined value, so when the contacts are free, the gap A between the sensor 13 and the sensor dog 15 is Thin springs 4a, 4b in the direction of minimum
The base ends of the arms 5a and 5b are in contact with the inner regulating ends 16a and 16b of the arm stopper 8.

21 is an amplifier, 22 is a linearizer, and 23 is an arithmetic unit. The output signal of the position sensor 13 is amplified by the amplifier 21, the deviation from linearity is corrected by the linearizer 22, and the amount of displacement is calculated by the arithmetic unit 23. be done.

The workpiece 20 is connected to two contacts 7a as shown by imaginary lines in the figure.
, 7b, if only the contact 7b of the arm 5b retreats, the displacement of the contact 7b causes the sensor dog 15 to retreat with respect to the sensor 13 by lever movement about the fulcrum pb. Similarly, when only the contact 7a of the arm 5a retreats, the displacement of the contact 7a causes the sensor 13 to retreat with respect to the sensor dog 15 by lever movement about the fulcrum Pa.

Furthermore, when the contactor 7a and the contactor 7b move backward at the same time, both the sensor 13 and the sensor dog 15 are displaced in a direction that increases the gap A between them, and the sum of their displacements is converted into an electrical signal by the sensor 13. Therefore, if the amount of displacement is calculated from the amount of electricity, the relative displacement of the two contacts 7a and 7b, that is, the displacement from the reference dimension of the diameter of the workpiece 20, can be directly measured using only one sensor 13. becomes possible.

(Effects) The two-finger electric micrometer of the present invention has a structure in which the relative movement of two contacts is converted into an electrical quantity by one position sensor and detected. Only one riser is required, reducing equipment cost. In addition, since the structure directly detects the relative movement of two contacts, the required accuracy can be satisfied by using a sensor that corresponds to the required minimum reading unit. Therefore, the sensor, its amplifier, linearizer, etc. The accuracy requirements for these methods are substantially relaxed, and if the accuracy is the same, these costs will be significantly reduced, and the achievable accuracy will also be higher.

[Brief explanation of the drawing]

FIG. 1 is a side view of the main parts showing one embodiment of the present invention, and FIG.
The figure is a side view of the main parts of a conventional device. In the figure, 1: base 5a, 5b: swing arm 6a,
6b: Finger 7a, 7b: Contact 13: Position sensor 15: Sensor dog 20: Work
Pa, Pb: Swing fulcrum A: Gap

Claims (1)

[Claims] Each fulcrum (Pa) and (Pb) formed on the base (1)
) The object to be measured (
In a two-finger electric micrometer that measures dimensions by sandwiching the arm (20), the position sensor (13) attached to one arm (5a) and the sensor dog (15) attached to the other arm (5b) are placed in a narrow gap ( A), and the gap (A) is located at the apex of an isosceles triangle whose base is a line segment connecting the fulcrum (Pa) of the arm (5a) and the fulcrum (Pb) of the arm (5b), Two contacts (7a), (
7b) A two-finger electric micrometer, characterized in that the relative displacement of 7b) is detected by one displacement sensor (13).