JP2011226879A - Measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring instrument capable of making a highly-precise measurement to reduce measurement errors that occur between the amount of spindle movement displayed on a digital indicator and the amount of actual spindle movement.SOLUTION: A measuring instrument, which measures the dimension of an object to be measured from the amount of spindle movement, includes a main body, a male screw section 31B with multiple threads formation and a rotary spindle that is installed movably in an axial direction in the main body. A projection member 70 contacting with a thread of the male screw section 31B is provided in a position facing the male screw section 31B of the main body. While the projection member 70 contacts with the thread, the spindle rotates and moves in the axial direction.

Description

  The present invention relates to a measuring instrument that measures the dimensions of an object to be measured.

2. Description of the Related Art Conventionally, a micrometer is known as a measuring instrument that measures a dimension of a device under test (for example, see Patent Document 1).
The micrometer includes a main body, a spindle that is rotatable on the main body and capable of moving in the axial direction, a thimble that is provided integrally with the spindle and rotates to advance and retreat in the axial direction, and a main body. And an encoder for detecting the amount of rotation of the spindle, and a digital indicator for digitally displaying the amount of movement of the spindle in the axial direction based on the detected value of the encoder.

  In such a micrometer, a male screw portion made of a plurality of screw threads is formed on the spindle, and a female screw portion made of a plurality of screw threads is formed on the main body at a position facing the male screw portion of the spindle. Then, the thread of the male thread part and the thread of the female thread part mesh with each other with the side surfaces of the thread thread in contact with each other. Accordingly, when the thimble is rotated, the spindle is also rotated at the same time, the male screw portion is moved forward and backward along the female screw portion, and the spindle is moved forward and backward with respect to the object to be measured. Since the movement amount of the spindle is displayed on the digital display based on the detection result by the encoder, the dimension of the object to be measured can be measured by reading the display value.

Japanese Utility Model Publication No. 47-27857

  However, in the conventional measuring instrument as described in Patent Document 1, the amount of movement of the spindle is determined by the structure of the thread of the male screw portion and the female screw portion. Since the male screw part and the female screw part each have a pitch error, a random walk error, etc., the meshing position of the screw thread of the male screw part and the screw thread of the female screw part changes, and the screw thread of the male screw part and the female screw part change. All the threads of the screw thread do not contact uniformly, and as a result, the movement amount of the spindle is influenced by the pitch error between the male screw part and the female screw part. For this reason, a measurement error occurs between the spindle movement amount displayed on the digital display and the actual spindle movement amount.

  An object of the present invention is to provide a measuring instrument that can reduce a measurement error generated between the actual moving amount of the spindle and perform highly accurate measurement.

  A measuring instrument according to the present invention includes a main body and a spindle having a male screw portion in which a male screw is formed, and is provided on the main body so as to be rotatable and movable in the axial direction. A projecting member that contacts one screw thread of the male threaded portion at a position facing the male threaded portion of the main body, and the projecting member contacts the threaded thread. However, the spindle rotates and moves in the axial direction.

  According to such a configuration, since the spindle rotates and moves in the axial direction while the projecting member contacts each screw thread, the spindle movement amount error is determined only by the pitch error of the male screw portion and the like. The position does not change. Therefore, a measurement error generated between the movement amount of the spindle read from the measuring instrument and the actual movement amount of the spindle can be reduced, and highly accurate measurement can be performed.

In the measuring instrument according to the present invention, the protrusion member has a semi-cylindrical protrusion centering on an axis orthogonal to the spindle axis, and the protrusion contacts one screw thread of the male screw portion. It is preferable to do.
According to such a configuration, the semi-cylindrical protrusion appropriately contacts one screw thread of the male screw portion. For this reason, the front end side of the spindle is supported by the main body, and the male screw portion on the rear end side of the spindle is supported by the protruding member via the protruding portion. That is, since the spindle is supported from both ends in the moving direction, the spindle does not shake and the spindle can always rotate around its central axis.

In the measuring instrument of the present invention, it is preferable that the protruding member is movable in a direction orthogonal to the spindle, and the protruding member is fixed to the main body by a fixing member from a direction intersecting the moving direction. .
According to such a configuration, the protruding member can be fixed at an arbitrary position, and the contact position between the protruding member and the screw thread of the male screw portion can be easily adjusted. Therefore, even if there is wear of the protruding member due to continuous contact between the protruding member and the screw thread of the male screw portion, the contact state can be adjusted to an optimum state.

The partially notched front view which shows the measuring device which concerns on embodiment of this invention. The elements on larger scale of FIG. The perspective view which shows the protrusion member which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A micrometer 1 shown in FIG. 1 includes a frame 2 formed in a substantially U shape.
An anvil 21 is fixed to the inner surface of one end of the frame 2, and a spindle 3 that moves in the axial direction while rotating and advances and retreats relative to the anvil 21 is provided at the other end.

  At the other end of the frame 2 provided with the spindle 3, a bearing cylinder 22 for supporting the spindle 3 is fixed on the inner surface side, and an inner sleeve 4 is fitted on the outer surface side. An outer sleeve 5 is fitted on the outer periphery of the inner sleeve 4. The frame 2, the inner sleeve 4 and the outer sleeve 5 constitute a main body.

A digital indicator 60 that digitally displays the amount of movement of the spindle 3 is disposed on the front surface of the frame 2. Between the bearing cylinder 22 and the inner sleeve 4, the spindle 3 moves in the axial direction from the amount of rotation of the spindle 3. An encoder 61 for detecting the amount is provided.
The encoder 61 is fixedly bonded to the plate 62 and has a transmission electrode and an output electrode (not shown). The encoder 61 is fixed in a state of facing the fixing plate 63 with a certain gap and has a reception electrode and a coupling electrode (not shown). When a signal having a different phase is given to the transmission electrode including the plate 64, a signal corresponding to the relative rotation angle between the fixed plate 63 and the rotating plate 64 can be obtained from the output electrode. A signal corresponding to the relative rotation angle between the fixed plate 63 and the rotating plate 64 detected by the encoder 61 is processed by an electric circuit (not shown) and then digitally displayed on the digital display 60.

  The spindle 3 includes a cylindrical shaft portion 31A, a male screw portion 31B having a slightly larger diameter than the shaft portion 31A and having a male screw formed on the outer peripheral surface, and an end portion on the retreat direction side of the spindle 3 with respect to the male screw portion 31B. Have a tapered portion 31C formed integrally with the male screw portion 31B. As shown in FIG. 2, screw threads N1, N2,... Are formed in the male screw portion 31B.

The inner sleeve 4 is formed in a substantially cylindrical shape, and a through portion 4a is formed inside. The spindle 3 is accommodated in the penetrating part 4a so as to be movable back and forth in the left-right direction in FIG.
As shown in FIG. 2, the inner sleeve 4 is formed with a mounting hole 4 b penetrating in a direction crossing the forward / backward moving direction of the spindle 3. In the mounting hole 4b, a protruding member 70 is screwed so as to be movable in a direction approaching the male screw portion 31B and a direction away from the male screw portion 31B, orthogonal to the spindle 3, facing the male screw portion 31B.

  As shown also in FIG. 3, the protrusion member 70 is provided integrally with the cylindrical body part 70a and the body part 70a closer to the male screw part 31B than the body part 70a, and becomes narrower toward the male screw part 31B. A square columnar support portion 70b having a substantially trapezoidal cross section, and a male screw portion centered on an axis orthogonal to the axis of the spindle 3 provided integrally with the support portion 70b on the male screw portion 31B side of the support portion 70b. It is comprised from the substantially semicylindrical protrusion part 70c which has the curved surface protruded to the 31B side.

  The protruding member 70 is inserted into the mounting hole 4b, and a fixing screw 80 as a fixing member is screwed from the side of the protruding member 70 in the traveling direction of the spindle 3 that intersects the movable direction of the protruding member 70. As a result, the fixing screw 80 comes into contact with the body portion 70 a, and the protruding member 70 is fixed in the mounting hole 4 b by the fixing screw 80. At this time, the protruding portion 70c protrudes toward one screw thread N1 of the male screw portion 31B, and the protruding portion 70c and the screw thread N1 come into contact with each other at the contact portion S.

The outer sleeve 5 is formed in a substantially cylindrical shape, and is attached to the outer side of the inner sleeve 4 so as to cover the outer periphery of the inner sleeve 4.
A thimble 50 is rotatably fitted on the outer peripheral surface of the outer sleeve 5. A main scale 51 is formed on the outer peripheral surface of the outer sleeve 5 at regular intervals along the axial direction of the outer sleeve 5, and a subscale 52 is formed along the outer periphery of the thimble 50.
The amount of movement of the spindle 3 can be read from the main scale 51 and the minor scale 52 and detected by the encoder 61 and then digitally displayed on the digital display 60.

  The end portion of the thimble 50 is fitted and fixed to the tapered portion 31C of the spindle 3. When the thimble 50 is rotated, the spindle 3 moves forward and backward with respect to the anvil 21 while rotating in synchronization with the rotation of the thimble 50. . At the other end of the thimble 50, there is provided a ratchet knob 53 that idles when a certain load or more is applied to the spindle 3.

Next, the operation of the micrometer 1 when measuring the dimensions of the object to be measured will be described.
First, an object to be measured is positioned between the anvil 21 and the tip of the spindle 3. At this time, as shown in FIG. 2, the projecting portion 70 c and the thread N <b> 1 are in contact with each other at the contact portion S.

  When the thimble 25 is rotated, the spindle 3 is moved forward toward the object to be measured. Then, the spindle 3 moves to the left in FIG. 2 while rotating, and the projecting portion 70c and the threads N2, N3,. At this time, the projecting portion 70c has a semi-cylindrical shape, and the side surface of the semi-cylindrical surface that is a curved surface is in proper contact with the threads N2, N3,... The male screw portion 31B is supported by the protruding member 70 via the protruding portion 70c. Therefore, the spindle 3 is supported from both sides in the moving direction, so that the rotation axis of the spindle 3 does not shake, and the spindle 3 can always rotate around its central axis.

  The thimble 50 is rotated until the tip of the spindle 3 contacts the object to be measured, and the rotation of the thimble 50 is stopped when the tip of the spindle 3 contacts the object to be measured. At this time, the ratchet knob 53 is rotated to keep the measurement pressure constant. Here, the movement amount of the spindle 3 is read from the main scale 51 and the minor scale 52 or from the digital display 60, thereby measuring the dimension of the object to be measured.

In the micrometer 1 of the present embodiment, the protruding member 70 is provided on the inner sleeve 4, and the protruding portion 70c protrudes toward the thread of the male screw portion 31B. In the micrometer 1 of the present embodiment, since the inner sleeve 4 is not provided with a female thread portion as in the prior art, the movement amount of the spindle 3 is not affected by the pitch error in the female thread portion, and the spindle 3 Is determined only by the pitch error of the male screw portion 31B, etc., so that the influence of the pitch error of the screw portion on the movement amount of the spindle 3 is reduced. Therefore, the amount of movement of the spindle 3 read from the main scale 51 and the subscale 52 based on the amount of rotation of the thimble 50 or the amount of movement of the spindle 3 detected by the encoder 61 and digitally displayed on the digital display 60, Measurement errors occurring between the actual movement amount of the spindle 3 can be reduced, and high-precision measurement can be performed.
Further, unlike the prior art, it is not necessary to provide a female thread portion on the inner sleeve 4, and the number of manufacturing steps of the micrometer 1 can be reduced.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the above embodiment, the micrometer 1 has been described as a measuring instrument. However, the present invention can be applied to any measuring instrument that measures the dimension of an object to be measured from the amount of movement of a spindle that moves forward and backward while rotating. For example, a so-called micrometer head in which the anvil 21 side of the frame 2 is cut off may be used.

  In the said embodiment, although the trunk | drum 70a of the projection member 70 demonstrated as a simple cylinder shape, the screw | thread may be cut into the trunk | drum 70a. Moreover, in the said embodiment, although the protrusion part 70c was a semicylindrical shape, a triangular prism shape may be sufficient. In this case, one inclined surface of the triangular prism comes into contact with the inclined surface of the screw thread, and the protrusion and the screw thread come into contact with each other.

  The present invention can be used in a measuring instrument that measures the dimensions of an object to be measured, such as a micrometer.

1 ... micrometer (measuring instrument),
2 ... Frame 3 ... Spindle,
4 ... Inner sleeve 5 ... Outer sleeve 31B ... Male thread part,
70 ... projection member,
70c ... protruding part,
80: Fixing screw (fixing member)
N1, N2, N3 ... Thread

Claims (3)

A measuring instrument that has a main body and a spindle having a male screw portion in which a male screw is formed, and is provided on the main body so as to be rotatable and movable in the axial direction, and measures the dimension of the object to be measured from the amount of movement of the spindle Because
A protruding member that contacts one screw thread of the male screw portion is provided at a position facing the male screw portion of the main body,
The measuring device according to claim 1, wherein the spindle rotates and moves in an axial direction while the protruding member is in contact with the screw thread. The measuring instrument according to claim 1, wherein
The projecting member has a semi-cylindrical protrusion centering on an axis orthogonal to the axis of the spindle, and the protrusion contacts one screw thread of the male screw portion. vessel. The measuring instrument according to claim 1 or 2,
The protruding member is movable in a direction perpendicular to the spindle;
The measuring device, wherein the protruding member is fixed to the main body by a fixing member from a direction intersecting the moving direction.

Images