JP6191161B2 - Encoder - Google Patents

Description

The present invention relates to encoders, in particular, it relates machine spindle, ball screw support bearings, vehicles such as automobiles and railroad, aircraft, to suitably encoder for use in general industrial machinery.

  Conventionally, it is used for a type using a magnetic bias type sensor that changes an output signal in response to a change in the magnetic characteristics of the surface to be detected, and has a C-shaped groove portion that becomes a surface to be detected on the outer peripheral surface. An encoder made of a magnetic material has been devised (for example, see Patent Document 1).

  Specifically, as shown in FIG. 7, the spacer 100 has a C-shaped groove portion 101, that is, the axis of the spacer 100 so that the distance between each other in the circumferential direction changes continuously in the axial direction. A plurality of pairs of grooves 102 inclined at substantially the same angle in opposite directions with respect to the direction are formed at equal intervals in the circumferential direction.

  Moreover, in patent document 2, such a C-shaped groove part 101 is formed by moving to a rotation axis direction after moving to a predetermined depth by helical processing using a tool such as an end mill. Have been described.

JP 2006-317420 A JP 2012-47663 A

  However, as described in Patent Document 2, the C-shaped groove portion 101 needs to be processed by feeding the end mill in the depth direction of the groove portion 101 as long as it does not penetrate to both ends of the spacer 100 in the axial direction. . Generally, the end mill is a side processing tool and is not very suitable for processing in the depth direction. For this reason, it may be difficult to process the C-shaped groove portion 101 with high accuracy.

The present invention has been made in view of the problems described above, and its object is accurately shaped groove Ha, and is to provide a encoder which can be processed easily.

The above object of the present invention can be achieved by the following constitution.
(1) An annular encoder that can rotate integrally with a rotating member and whose outer peripheral surface constitutes a detected surface,
A plurality of grooves each having a pair of grooves inclined at substantially the same angle in opposite directions with respect to the axial direction of the encoder so that the interval in the circumferential direction continuously changes in the axial direction on the outer peripheral surface. A set of detected parts are formed at equal intervals in the circumferential direction; and
Wherein the outer peripheral surface, before Symbol plurality of sets of a pair of circumferential grooves at both axial ends and each successive respective grooves of the detection unit is formed, and,
Each of the circumferential grooves is formed at a position away from both edges in the axial direction of the encoder.
(2) The encoder according to (1), wherein a depth of the circumferential groove is equal to or greater than a depth of the pair of groove portions.
(3) The circumferential edge portions constituting each groove are formed in a straight line shape to both ends in the axial direction continuous with the circumferential groove when viewed from the radial direction (1) or The encoder according to (2).
(4) The encoder according to any one of (1) to (3), which is incorporated into a spindle for machine tools .

According to encoder of the present invention, the outer peripheral surface, a pair of circumferential grooves each successive axially opposite ends of each groove is formed, and each circumferential groove, remote from the axial edges of the encoder Formed in each position . In other words, by providing circumferential grooves in advance at both axial ends of the C-shaped groove, it becomes possible to process the C-shaped groove without giving the tool feed in the depth direction. The U-shaped groove can be processed accurately and easily.

  In addition, since the C-shaped groove is formed by helical processing, the C-shaped groove can be accurately and easily processed.

  Moreover, since the axial direction both ends of each groove part which continues with a circumferential groove are formed in the linear shape, sensing accuracy can be improved.

  Furthermore, since the depth of the circumferential groove is equal to or greater than the depth of the pair of groove portions, the C-shaped groove portion can be accurately and easily processed without feeding the end mill in the depth direction. it can.

It is principal part sectional drawing of the front side bearing vicinity of the spindle for machine tools with which the encoder of this invention is applied. It is a perspective view of the encoder of FIG. (A) is a front view of the encoder of FIG. 1, (b) is sectional drawing along the III-III line of (a). (A) is the partial expanded front view of the encoder of this invention, (b) is the partial expanded front view of the conventional encoder. It is a diagram which shows the output signal of the sensor which changes with the fluctuation | variation of an axial load. (A) is a first modification of the encoder, (b) is a second modification of the encoder, and (c) is a third modification of the encoder. (A) is a front view of a conventional encoder, and (b) is a perspective view of (a).

Hereinafter, an encoder of the present invention will be described in detail based on the drawings.
FIG. 1 is a cross-sectional view of a main part in the vicinity of a front bearing of a machine tool spindle to which an encoder is applied. A rotating shaft 11 that is a rotating member is provided at the center of the spindle 10, and a tool (not shown) is attached to the end in the axial direction. The rotating shaft 11 is rotatably supported by the housing 12 by a pair of front bearings 20 and 21 and a rear bearing (not shown).

  The front bearings 20, 21 include an outer ring 22 fitted in the housing 12, an inner ring 23 fitted on the rotary shaft 11, and a plurality of rolling elements 24 arranged with a contact angle therebetween. Each is an angular ball bearing. The pair of front bearings 20 and 21 are arranged so as to be a back combination through the outer ring spacer 13 and the inner ring spacer 1 constituting the encoder.

  A sensor mounting hole 12a and a through hole 13a are formed continuously in the radial direction in the housing 12 and the outer ring spacer 13. The sensor 31 of the sensing system 30 is inserted into the sensor mounting hole 12a and the through hole 13a. The sensor 31 is a magnetic bias type sensor having a detection unit 32 at the tip and a magnet 33 incorporated therein. Further, the sensor 31 is positioned at a predetermined position and is disposed to face a detection surface formed on the outer peripheral surface 2 of the inner ring spacer 1.

  As shown in FIGS. 2 and 3, the outer circumferential surface 2 of the annular inner ring spacer 1 is arranged in the axial direction of the inner ring spacer 1 so that the interval in the circumferential direction continuously changes in the axial direction. On the other hand, a plurality of sets of detected portions 5 each having a pair of groove portions 4 constituting a C-shaped groove portion 3 inclined at substantially the same angle in opposite directions are formed at equal intervals in the circumferential direction.

  Further, on the outer peripheral surface 2 of the inner ring spacer 1, a pair of circumferential grooves that are respectively continuous with both axial ends of the respective groove portions 4 of the plurality of sets of detected portions 5 at positions away from both axial edge portions 2 a thereof. 6 is formed. As a result, as shown in FIG. 4 (a), both circumferential edges 4a constituting each groove 4 are formed in a straight line shape to both axial ends continuous with the circumferential groove 6 when viewed from the radial direction. Yes. Further, the depth of the circumferential groove 6 is preferably equal to or greater than the depth of the pair of groove portions 4, and the axial width of the circumferential groove 6 is equal to or greater than the radius of the end mill to be used. It is preferable that it is more than the diameter of an end mill. In the present embodiment, the axial widths of the circumferential grooves 6 on both sides are set to the same dimension.

The inner ring spacer (encoder) 1 configured in this way is firstly paired so that the depth is equal to or greater than the depth of the pair of grooves 4 at a position away from both axial edges 2a of the outer peripheral surface 2. The circumferential groove 6 is processed in advance. And a pair of groove part 4 is formed by helical processing, without giving the feed of a depth direction to an end mill.
Further, since the pair of circumferential grooves 6 are formed at positions away from the both axial edges 2a of the outer peripheral surface 2, they do not affect the axial end surface that contacts the inner ring 23.

  As shown in FIG. 5, the sensing system 30 configured in this way senses a change in which the magnetic field of the magnet 33 built in the sensor 31 is turned on and off by the pair of grooves 4 of the encoder 1. At this time, when axial displacement is given to the encoder 1 by an external load, the on / off cycle of the magnetic field (cycle 1: between the pair of grooves 4, cycle 2: between each detected portion 5) changes depending on the angle of the groove 4. However, this cycle ratio (cycle 1 / cycle 2) is calculated and converted into displacement and load. In order to accurately sense this period ratio, the pair of grooves 4 need to be formed with high accuracy in both angular accuracy and linear accuracy.

  Here, in the conventional encoder 100 shown in FIG. 4B and FIG. 7, the pair of groove portions 102 include a straight portion 102 a 1 and a curved portion 102 a 2 in the opening edge portion 102 a when viewed from the radial direction. The change in the ON / OFF cycle due to the axial displacement of the encoder 1 described in FIG. 5 is constant in the linear portion 102a1, and high-accuracy measurement is possible, but the change is not constant in the curved portion 102a2, and a measurement error occurs. become. Thus, in the conventional encoder 100, there is a range in which a measurement error due to the curved portion 102a2 occurs during the transition from the range in which high-precision measurement by the straight portion 102a1 is possible to the non-measurable range outside the groove portion 102 in the axial direction. Further, in such a groove 102, it is difficult to determine the transition from the high-accuracy measurement range to the measurement error occurrence range, so the measurement accuracy is lowered. On the other hand, in the encoder 1 of the present embodiment, as shown in FIG. 4A, the pair of groove portions 4 do not have a curved portion, and the annular portion 6 from the high-precision measurement range by the linear circumferential edge 4a. Since the shift is directly made to the non-measurable range according to, the determination of the shift is easy, so that the measurement accuracy as a sensor is improved.

  As described above, according to the encoder 1 of the present embodiment, a pair of circumferential grooves that are respectively continuous with both axial ends of the groove portions 4 on the outer peripheral surface 2 at positions away from both axial edge portions 2a. 6 is formed. That is, by providing circumferential grooves 6 at both axial ends of the C-shaped groove 3 in advance, the C-shaped groove 3 is subjected to a helical process without feeding the end mill in the depth direction. Therefore, the U-shaped groove 3 can be processed accurately and easily.

In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, in the encoder 1 of the above embodiment, the cross-sectional shape of the circumferential groove 6 is a rectangular shape, but is not limited to this, the curved shape shown in FIG. 6A, the straight line and the curved line shown in FIG. The effect can be expected with any shape such as the composite shape of FIG. 6 and the shape of the single circumferential groove shown in FIG. Further, in the above embodiment and the shape as shown in FIGS. 6B and 6C, if the straight portion 6a exists on the circumferential wall surface of the connecting portion of the pair of groove portions 4, the straight portion 6a is processed and accuracy is lowered. The accuracy of the pair of groove portions 4 can be expected to be improved. Further, the cross-sectional shapes of the pair of circumferential grooves 6 may be different from each other by combining FIGS. 6A to 6C and the like.

DESCRIPTION OF SYMBOLS 1 Encoder 2 Outer peripheral surface 3 C-shaped groove part 4 Groove part 5 Detected part 6 Circumferential groove

Claims (4)

An annular encoder that can rotate integrally with the rotating member and whose outer peripheral surface constitutes the detected surface,
A plurality of grooves each having a pair of grooves inclined at substantially the same angle in opposite directions with respect to the axial direction of the encoder so that the interval in the circumferential direction continuously changes in the axial direction on the outer peripheral surface. A set of detected parts are formed at equal intervals in the circumferential direction; and
Wherein the outer peripheral surface, before Symbol plurality of sets of a pair of circumferential grooves at both axial ends and each successive respective grooves of the detection unit is formed, and,
Each of the circumferential grooves is formed at a position away from both edges in the axial direction of the encoder.   The encoder according to claim 1, wherein a depth of the circumferential groove is equal to or greater than a depth of the pair of groove portions.   3. The circumferential both edges constituting each groove are formed in a straight line shape up to both ends in the axial direction continuous with the circumferential groove as viewed from the radial direction. 4. Encoder. The encoder according to any one of claims 1 to 3, wherein the encoder is incorporated in a spindle for a machine tool .

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