GB2182151A - Coaxial linear magnetic scale apparatus - Google Patents
Coaxial linear magnetic scale apparatus Download PDFInfo
- Publication number
- GB2182151A GB2182151A GB08624724A GB8624724A GB2182151A GB 2182151 A GB2182151 A GB 2182151A GB 08624724 A GB08624724 A GB 08624724A GB 8624724 A GB8624724 A GB 8624724A GB 2182151 A GB2182151 A GB 2182151A
- Authority
- GB
- United Kingdom
- Prior art keywords
- magnetic scale
- scale
- linear magnetic
- coaxial
- guide shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
- A Measuring Device Byusing Mechanical Method (AREA)
Abstract
A coaxial linear magnetic scale apparatus used in a machine tool or the like, includes a linear magnetic scale 5 recorded with an AC magnetic pattern at a predetermined pitch on a rod-like magnetic medium, and a multigap head having a scale hole through which the magnetic scale is coaxially inserted. The apparatus also includes a hollow guide shaft 1 having one end fixed to the multigap head 4 and slidably mounted on the magnetic scale frame 3. One end of the linear magnetic scale is fixed to the magnetic scale frame and its other end is slidable along the inner surface of the hollow guide shaft which is coaxial with the-linear magnetic scale. The overall length of the magnetic scale apparatus is thus reduced to obtain a compact apparatus. Since the hollow guide shaft is coaxial with the shaft of the linear magnetic scale, the relative positional relationship between the hollow guide shaft and the linear magnetic scale is kept constant, even if the hollow guide shaft is inclined, thereby greatly reducing measurement errors. <IMAGE>
Description
SPECIFICATION
Coaxial linear magnetic scale apparatus
The present invention relates to a magnetic scale apparatus used ina machinetool orthelikeand, more particularly, to an improvement in a coaxial linear magnetic scale apparatus.
Since measuring systems for measuring lengths and angles, by use of a magnetic scale, have high measurement precision, they have been used in a variety of industrial applications. In recent years, they have also been applied in the field of automatic control. Among these magnetic scales, a coaxial linear magnetic scale apparatus has a variety of applications and has been the most popular, since it is compact and simple, and can be mounted at any location.
Aconventional coaxial linearmagneticscale apparatus comprises a linear magnetic scale recorded with an linear magnetic pattern at a predetermined pitch on a rod-like magnetic medium, and a multigap head having a hole through which the magnetic scale is inserted. The magnetic scale is inserted in the scale hole of the multigap head, to thereby constitute a concentric linear magnetic scale apparatus. In this measuring system, one ofthe linear magnetic scales and the multigap head are fixed, and the other is coupled to a moving object.
Upon movement of the moving object, a signal from the multigap head is electrically processed to measure the displacement ofthe moving object.
Atypical conventional structure of the linearmagneticscale and the multigap head is illustrated in
Figure 2. Linear magnetic scale 21 is fixed to guide shaft 20 coupled to a moving object, such as a blade table of a machine tool, to constitute an integral unit.
The integral unit can be slid, by linear ball bearing 22, with respectto magnetic scale housing 23. Multigap head 24 having a scale holethroughwhichthe mag- neticscale is inserted, is fixed to housing 23. Scale 21 is inserted in the scale hole, and is moved upon movement of guide shaft 20. A signal representing the displacement of scale 21 is extracted via flexible cable 26.
With the above construction, however, magnetic scale housing 23 must have the same length as that of scale 21, as shown in Figure 2. Therefore, the magnetic scale apparatus is made long, and because of its length, its mounting position is restricted, when it is mounted on a machinetool orthe like. In some cases, a spacer or attachment must be used to mount the apparatus on the machinetool,thus resulting in inconvenience. Alternatively, if scale 21 is fixed and head 24 is movable, head 24 is fixed to shaft 20 slidably mounted on housing 23, by means of bearing 22, as is shown in Figure 3. Scale 21 is fixed to housing 23 by fastening piece 25, at a position spaced apart from shaft 20 and parallel thereto. At the same time, scale 21 is inserted in the scale hole of head 24 fixed to shaft 20. Head 24 is moved upon movement of shaft 20.A signal representing its displacement is extracted via cable 26. With this construction, shaft 20 is not integral with scale 21, but is separated therefrom. If shaft 20 is inclined with respect to the shaft of scale 21, due to degradation of the working precision of shaft 20, the relative relationship between scale 21 and head 24 causes positional errors. Errors then occur in the measured values, and accurate measurement cannot be performed.
The present invention has been made in consideration of the above situation, and has as its objectto provide a magnetic scale apparatus wherein the overall length of the magnetic scale apparatus can be minimized, and errors caused by inclination of a guide shaft can be eliminated.
In a coaxial linear magnetic scale apparatus ofthe present invention, a hollow guide shaft is fixed in tegrallywitha multigap head, and one end of a linear magnetic scale is fixed to a magnetic scale frame, such that the linear magnetic scale is coaxial with the hollow guide shaft, and the other end of the linear magnetic scale is provided with a guide portion, so asto slide the linear magnetic scale along the inner surface ofthe hollow guide shaft, by means ofthe guide portion, thereby storing the linear magnetic scale insidethe hollow guide shaft.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Figure lisa schematic sectional view showing an embodiment of the present invention; Figure2 is a schematic sectional view of a conventional coaxial linear magnetic scale apparatus of a multigap head fixed type; and
Figure 3 is a schematic sectional view of a con ventional coaxial I I i n ea r magnetic scale apparatus of a magnetic scale fixed type.
A coaxial linear magnetic scale apparatus of the present invention is arranged as follows:
A guide shaft coupled to a moving object, such as a blade table of a machine tool, comprises hollow guide shaft 1, multigap head 4 is fixed to an end of shaft 1, and shaft 1 isslidableon magnetic scale frame 3, by means of linear ball bearing 2. One end of scale 5 is cantilevered on support member 7, by means of fastening piece 6. Support mem ber 7 is formed on frame 3. The other end of scale 5 is inserted in the scale hole of head 4fixed to shaft 1. Scale 5 is guided, by guide portion 8 at the distal end of linear magnetic scale 5, along inner surface 9 of shaft 1.Coil spring 10, hooked between support member7 and head 4, urges head 4 and shaft 1 along scale 5, and toward the outside of frame 3, so that shaft 1 can be smoothly returned to its original position.
In the coaxial linear magnetic scale apparatus with this construction, when hollow guide shaft 1 coupled to the moving object, such as a blade table of a machine tool, is slid upon movement of the blade table orthe like, head 4fixed to the shaft, is moved while spaced aparttherefrom by a predetermined distance. Head 4 reads the magnetic pattern ofthe magnetic scale, according to its own displacement. A signal is extracted via flexible cable 11. As hollow guide shaft 1 moves, multigap head 4 is slid along inner surface 9 by guide portion 8, the other end of which is provided with scale 5, and is inserted inside shaft 1. Shaft 1 is coaxial with scale 5.
According to the present invention, the overall length of the magneticscale apparatus, with respect to a movable length of scale 5, can be reduced to made the apparatus compact. In addition, since shaft 1 is coaxial with the shaft of scale 5, no relative position error occurs between scale 5 and head 4, even if shaft 1 is inclined. As a result, no errors in measured values occur.
Claims (2)
1. A coaxial linear magnetic scale apparatus including a linear magnetic scale and a multigap head having a scale hole through which said magnetic scale is inserted, said magnetic scale being inserted in said scale hole of said multigap head, to be coaxial therewith, and comprising a hollow guide shaft having one end fixed to said multigap head and slidably mounted on said magnetic scale frame, and a linear magnetic scale, one end of which is fixed to said magnetic scale frame, and the other end ofwhich is siidable along the innersurface of said holiow guide shaft as a guide, wherein said hollow guide shaft is coaxial with said linear magnetic scale.
2. A coaxial linear magnetic scale apparatus, substantially as hereinbefore described with reference to
Figure 1 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23637485A JPS6296801A (en) | 1985-10-24 | 1985-10-24 | Coaxial type linear magnetic scale device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8624724D0 GB8624724D0 (en) | 1986-11-19 |
| GB2182151A true GB2182151A (en) | 1987-05-07 |
Family
ID=16999845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08624724A Withdrawn GB2182151A (en) | 1985-10-24 | 1986-10-15 | Coaxial linear magnetic scale apparatus |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS6296801A (en) |
| CN (1) | CN86107110A (en) |
| DE (1) | DE3635623A1 (en) |
| GB (1) | GB2182151A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2032940B1 (en) * | 2006-06-16 | 2010-05-05 | Renishaw PLC | Extendable leg assembly for position measurement apparatus |
| CN107966094A (en) * | 2017-11-17 | 2018-04-27 | 山东大东联石油设备有限公司 | A kind of oil well pump displacement detection device for being placed in underground installation |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1393093A (en) * | 1971-07-26 | 1975-05-07 | British Non Ferrous Metals Res | Die casting or injection moulding machines |
| GB2056692A (en) * | 1979-08-18 | 1981-03-18 | Bosch Gmbh Robert | Magnetic measurement of position and/or speed of a piston |
| GB2098332A (en) * | 1979-11-14 | 1982-11-17 | Festo Maschf Stoll G | Position sensor |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4946740B1 (en) * | 1969-09-10 | 1974-12-11 | ||
| JPS5914305B2 (en) * | 1981-03-18 | 1984-04-04 | 東芝機械株式会社 | Ram displacement detection device in die-casting machine |
| DE3127116C2 (en) * | 1981-07-09 | 1994-09-01 | H. Kuhnke Gmbh Kg, 2427 Malente | Measuring system for contactless detection of positions in a piston-cylinder unit |
-
1985
- 1985-10-24 JP JP23637485A patent/JPS6296801A/en active Pending
-
1986
- 1986-10-15 GB GB08624724A patent/GB2182151A/en not_active Withdrawn
- 1986-10-20 DE DE19863635623 patent/DE3635623A1/en not_active Withdrawn
- 1986-10-23 CN CN198686107110A patent/CN86107110A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1393093A (en) * | 1971-07-26 | 1975-05-07 | British Non Ferrous Metals Res | Die casting or injection moulding machines |
| GB2056692A (en) * | 1979-08-18 | 1981-03-18 | Bosch Gmbh Robert | Magnetic measurement of position and/or speed of a piston |
| GB2098332A (en) * | 1979-11-14 | 1982-11-17 | Festo Maschf Stoll G | Position sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3635623A1 (en) | 1987-04-30 |
| GB8624724D0 (en) | 1986-11-19 |
| JPS6296801A (en) | 1987-05-06 |
| CN86107110A (en) | 1987-04-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |