JP2013079982A - Method for replacing encoder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that a conventional encoder head is difficult to replace, requires a considerable time in the replacement, furthermore, requires highly accurate positioning work in the replacement, has a complicated component configuration, and requires high working accuracy.SOLUTION: A linear encoder includes: a housing 1 for storing a scale; an end block 2 for fixing the housing 1 to an object; and an encoder head 3 for scanning the scale to acquire position information and to which a sensor unit is connected. A method for replacing the encoder head in the linear encoder comprises: a) removing the encoder head fixed to the object, from the object and moving it; b) fixing the object to which the encoder head has been attached, to the housing with a tool; c) removing the end block; and d) removing the encoder head along with a detector unit, from the housing.

Description

  The present invention relates to a method for exchanging a head of a linear encoder used for measuring a relative position of objects movable relative to each other, in particular, for measuring a position of a work, a processing apparatus or the like.

  In a machine tool or the like, it is extremely important to accurately measure the relative movement amount of a tool with respect to a workpiece, and various measuring apparatuses for this purpose have been commercialized.

  As such a measuring apparatus, a linear encoder that detects an absolute position by a relatively moving detector is known. As an example of a conventional linear encoder, FIGS. 13 and 14 show a linear encoder in which a measurement scale is housed in a rectangular tubular case. FIG. 13 is a front view of a conventional linear encoder, and FIG. 14 is a plan view. In the illustrated linear encoder, a housing 1 for storing a measurement scale, an end block 2 for fixing the housing 1 to an object, and a sensor unit for scanning the scale stored in the housing 1 to obtain position information are connected. Encoder head 3. The end block is provided with a fixing screw hole 11, and the encoder head 3 is also provided with a fixing screw hole 31, which are screwed to one of the relative movable objects and the other, respectively, in the housing. The amount of movement can be measured by the scale.

  However, the linear encoder having such a structure cannot be easily removed because the end block 2 is adhered when a malfunction occurs in the detector and the encoder head needs to be removed. For this reason, usually, it is necessary to remove the entire linear encoder, take it home, perform repairs and adjustments, and then reassemble the linear encoder. This again forces the end user or field worker to perform the difficult task of determining the position accuracy of the encoder. Further, during the period when the encoder is being repaired, it is not possible to operate the object such as a machine tool or a processing apparatus, which causes a problem that productivity is lowered. Furthermore, the mounting accuracy of the encoder depends on the dimensional accuracy of a plurality of parts such as the housing 1 and the end block 2, and it becomes difficult to manage the mounting accuracy.

  On the other hand, if the end block 2 is to be removed while attached to the object, one fixed end of the housing 1 will be lost, and the housing will move and the encoder mounting accuracy will be greatly impaired.

  European Patent No. 1445584 and Japanese Patent Laid-Open No. 10-221022 (Patent Document 1) have a length measuring device with an assembly block that guarantees accurate and reproducible position measurement whose end face side can be easily manufactured. For the purpose of scanning the measuring rule 2 in the direction of the measuring direction X, which is arranged inside the tubular housing 1 and the measuring rule 2 inside the housing, for the purpose of being tightened In this case, the end face side end of the housing 1 is closed by an assembly block 5 so that the housing 1 is an object to be measured by the assembly block. In the length measuring device which can be fixed, at least one insertion member 10, 20 is fixed to or formed on the assembly block 5, and the insertion member The length measuring device is inserted into the voids 11 and 21 of the housing 1 and the assembly block 5 is constrained integrally with the housing 1 in the measuring direction X by the engagement. Is disclosed. That is, the length measuring device of this document has an assembly block 5 at the housing end 1.

  However, in the length measuring device of this document, the housing 1 and the assembly block 5 occupy different portions in the length direction of the housing, and the mounting accuracy of the length measuring device is that of each part of the housing 1 and the assembly block 5. It depends on the dimensional accuracy. For this reason, high-accuracy processing is required in both the housing 1 and the assembly block 5, and the dimensional management becomes complicated. Further, since the insertion member 10 of the assembly block 5 is inserted from a direction perpendicular to the length direction of the housing 1, depending on the force required for the insertion, the housing 1 moves in the vertical direction and the position accuracy is likely to be incorrect. .

  Furthermore, the slit 8 of the housing 1 is sealed by the seal lips 6.1 and 6.2, but both ends of the housing are only sealed by the assembly block 5, and the housing 1 is completely sealed and dust-proof environment. Insufficient to form. In order to improve the sealing and dustproof performance, it is necessary to process the joint surface between the housing 1 and the assembly block 5 with high precision, but this is not desirable because it increases the cost of the linear encoder.

  In U.S. Pat. No. 5,832,616 and Japanese Patent Application Laid-Open No. 2004-245591 (Patent Document 2), a high-precision measurement is possible by attaching a scale member having a different linear expansion coefficient to a device with high accuracy regardless of environmental conditions. The scale member 6 is formed of a long member provided with a position signal, and a pair of co-tightening holes 12 are formed with the position signal forming part 11 interposed therebetween. The scale portion 4 including a case member 7 having a pair of attachment holes 15 into which the attachment members 13 to be inserted into the attachment portions 10 housed in the device fixing portions 2 and screwed into the attachment portions 10 are formed. The detection sensor 29 is attached to the moving device moving portion 3 and the detection sensor 29 is moved to face the position signal forming portion 11 of the scale member 6. Le unit 4, the scale device is disclosed which is fixed by co-fastening the scale member 6 and the case member 7 by a mounting member 13.

  The scale device of this document has a pair of left and right side case members 9A and 9B, and this side case member 9 is substantially equal to the shape of the opening on both sides of the first case member 7 as shown in FIG. It consists of a plate-like base portion 19 having an outer shape and a spacer portion 20 that is integrally formed on the inner surface of the base portion 19. In the side case member 9, a guide hole 21 positioned coaxially with the mounting hole 15 and the guide hole 16 of the first case member 7 in a state of being combined with the first case member 7 penetrates the spacer portion 20. Is formed. Further, the spacer portion 20 is between the first main surface 6 a of the scale member 6 joined to the first side surface portion 7 b of the first case member 7 and the second side surface portion 7 c of the first case member 7. The first case member 7 is assembled so as to be inserted. In the combined state, the first side surface 20 a of the spacer portion 20 is in contact with the first main surface 6 a of the scale member 6, and the second side surface 20 b is in contact with the inner surface of the second side surface portion 7 c of the first case member 7. As a result, the opening side surfaces of the first case member 7 and the second case member 8 are closed, and the facing distance between the first side surface portion 7b and the second side surface portion 7c is maintained via the scale member 6.

  In the scale device of this document, the seal lip members 24A and 24B are attached to the inner surfaces of the side surfaces protruding from the lower end edges of the first side surface portion 7b and the second side surface portion 7c of the first case member 7, This part is sealed. However, both end portions of the first case member 7 are sealed with the side case member 9, but a high-precision optical encoder is not sufficient to form a complete sealing and dustproof environment. In order to improve the sealing and dustproof performance, it is necessary to process the joint surface between the first case member 7 and the side case member 9 with high accuracy, but this is not desirable because it increases the cost of the linear encoder.

  Further, in the structure of this document, the scale member 6 and the case member 7 are fastened together by the attachment member 13, so that when the attachment member 13 is removed to remove the side case member 9, one end of the scale member 6 is removed. Is lost, the scale member 6 moves easily, and the mounting accuracy is lost.

JP 10-221022 A (European Patent No. 1445584) Japanese Patent Application Laid-Open No. 2004-245591

  The problem to be solved is that it is difficult to replace the encoder head, and it takes time to replace the encoder head. In addition, the positioning of the encoder requires high precision. This is a required point. In addition, when the encoder is replaced, the apparatus on which the encoder is mounted is stopped, and if the period is long, a heavy burden is placed on the user. Furthermore, the device must be disassembled for removal.

The present invention has the following configuration in order to solve the above problems.
(1) a housing for housing the scale;
An end block for fixing the housing to the object;
An encoder head replacement method in a linear encoder having an encoder head connected to a sensor unit that scans a scale and obtains position information,
a) Remove the encoder head fixed to the object from the object and move it,
b) Fix the object to which the encoder head was attached and the housing with a jig,
c) Remove the end block,
d) A method of replacing the encoder head, which removes the encoder head from the housing together with the detector unit.
(2) The method for replacing an encoder head according to (1), wherein the jig is attached to an object using an encoder head attachment structure.

  The method for replacing the encoder head in the linear encoder of the present invention is very easy to replace the encoder head having the sensor unit, and does not require time for replacement, and does not require high-accuracy positioning. In addition, the encoder has a simple configuration and no machining accuracy is required.

FIG. 1 is a partial perspective view of a linear encoder. Example 1 FIG. 2 is a partially transparent view of FIG. Example 1 FIG. 3 is a side view of FIG. Example 1 4 is a partial cross section AA view of FIG. Example 1 FIG. 5 is a perspective view of FIG. Example 1 FIG. 6 is a perspective view showing an end block disassembly process. Example 1 FIG. 7 is a perspective view showing an end block disassembly process. Example 1 FIG. 8 is a perspective view showing an end block disassembly process. Example 1 FIG. 9 is a perspective view showing a process of removing the encoder head. (Example 2) FIG. 10 is a perspective view showing a process of removing the encoder head. (Example 2) FIG. 11 is a perspective view showing a process of removing the encoder head. (Example 2) FIG. 12 is a perspective view showing a process of removing the encoder head. (Example 2) FIG. 13 is a front view showing a conventional linear encoder. FIG. 14 is a plan view showing a conventional linear encoder.

  The linear encoder of the present invention scans, for example, a housing 1 for storing a measurement scale, end blocks 2a and 2b for fixing the housing 1 to an object, and a scale stored in the housing 1, as shown in FIG. An encoder head 3 to which a sensor unit for obtaining position information is connected, and a part or all of the end block is accommodated in the housing, and an end block accommodating portion and a scale accommodating portion in the housing There is a sealing member in between, and the housing is fixed to an object by a fixture through an end block.

  Thus, by storing the end block for fixing the housing in the housing, it is not necessary to increase the dimensional accuracy required for the end block, and the accuracy required for the fixing structure of the housing can be suppressed to a low level. Thus, the cost of the linear encoder can be reduced. Further, since the end block is fixed by a fixing tool, the end block can be easily removed, and the encoder head can be replaced without removing the housing itself. Furthermore, since the scale housing portion of the housing has a sealing member, high sealing and dustproof performance can be obtained without being affected by the processing accuracy of the housing end and end block.

  In the present invention, part or all of the end block that is provided at the end as a separate body from the conventional housing is housed in the housing. In other words, the housing is extended to the fixed portion at the end so that only the housing contacts the mounting surface, and the mounting accuracy depends entirely on the dimensions of the housing. By doing so, it is only necessary to manage the housing accuracy in a unified manner with respect to the size of the housing. This facilitates the positioning operation and improves the mounting accuracy and reproducibility.

  The end block may be provided separately as a fixing block for fixing the housing and a terminal block for closing the end of the housing. By separating the end blocks, an optimum shape, dimensional accuracy, and material can be obtained in accordance with the function of each block.

  Furthermore, in the linear encoder of the present invention, the shape of the housing in the longitudinal direction can be made symmetrical, and the sectional shape of the housing can also be made symmetrical or line symmetric. For this reason, for example, when changing from one side to the other side (front and back, etc.) of the processing device that is the object to be measured, the conventional one that had to be mounted by inverting the housing is used as it is. It can be attached simply by changing the mounting surface of the housing. That is, in the past, the position (direction) of one end and the other end of the linear encoder has been changed by 180 °, and the linear encoder is attached without changing the position (direction) of the end. For this reason, it is not necessary to change the measurement direction, and the items to be changed in the process of processing or using the measurement data can be extremely reduced.

  With the linear encoder of the present invention having the above structure, the end block can be easily removed. For this reason, the encoder head having the sensor unit can be detached and adjusted, repaired, or the like. More specifically, the following procedure is used. 1) The encoder head fixed to the object is removed from the object and moved to an unobstructed position. 2) The object to which the encoder head is attached and the housing are fixed by a jig. 3) End block 4) Remove the encoder head from the housing together with the detector unit. Then, when the encoder head is attached and restored to the original state, the reverse procedure may be performed.

  Specific configurations of the linear encoder are shown in FIGS. 1 is a partial perspective view of the linear encoder, FIG. 2 is a partially transparent view thereof, FIG. 3 is a side view, FIG. 4 is a partial cross-sectional view taken along the line AA, FIG. 5 is a perspective view of FIG. -8 are exploded block diagrams of the end block. The linear encoder of the illustrated example scans a housing 1 for storing a measurement scale, an end block 2 (2a, 2b) for fixing the housing 1 to an object, and a scale stored in the housing 1 to obtain position information. And an encoder head 3 to which a sensor unit to be obtained is connected.

  The end block 2 has both a function of closing the housing end and a function of fixing the housing. In this example, each function is divided into two blocks. Specifically, there are a fixing block 2b housed in the housing and a terminal block 2a for closing the housing end.

  The fixing block 2b is a rectangular block having a size that can be stored in the housing, and has an attachment hole 21 that can be fixed by a fixing tool 12 such as a screw. The fixing block 2b is stored in the end block storage portion 1b in the housing 1, the fixing tool 12 is inserted from the fixing opening 11 of the housing, and a fixing tool such as a screw is used for the object through the mounting hole 21. Tighten, press, crimp and fix. At this time, the housing 1 between the object and the fixing block 2b is also pressed and fixed to the object by the fixing block 2b. The fixing tool 12 may be a general screw applying the principle of a slope as shown in the figure, but may be a mechanism having a function of tightening and fixing by a rotating operation such as a bayonet mechanism, and may be crimped in some cases. It may be a pin or the like and is not particularly limited.

  The fixing block 1b has an attachment hole 21 attached to the object, and a diameter-enlarged portion 23 formed on the opposite side of the attachment hole 21 from the object fixing surface via a step portion 22. Usually, the head portion of the fixing tool is accommodated in the enlarged diameter portion, and the step portion is pressed and fixed to the object side by tightening the fixing tool.

  The fixing block 1b has an attachment hole 21 attached to the object, and a diameter-enlarged portion 23 formed on the opposite side of the attachment hole 21 from the object fixing surface via a step portion 22. Usually, the head portion of the fixing tool is accommodated in the enlarged diameter portion, and the step portion is pressed and fixed to the object side by tightening the fixing tool.

  As shown in FIG. 6, the end block 2 a is a plate-like body formed so as to have substantially the same size and shape as the end face of the housing 1. Further, on the back side that is the inside of the housing, there is a support column 214 for connecting to a sealing member 4 described later. A stop hole 213 penetrating to the front side is formed in the support post 214. The end block 2a is preferably substantially the same size and shape as the end face of the housing 1 in order to close the end of the housing 1, but at least the object in order to ensure adhesion between the housing 1 and the object. The side may be formed in the same level as the side surface of the housing or in a size that is slightly recessed. The thickness of the terminal block 2a is not particularly limited as long as the necessary strength can be ensured.

  In this example, the fixing block 2b and the terminal block 2a are divided into two blocks, but they may be integrally formed. The material constituting the end block 2a is preferably the same material in order to unify the appearance with the housing 1. Specific examples include aluminum, stainless steel, or iron surface-treated materials. Further, part or all of the terminal block 2a may be made of a resin material, an elastomer, or the like in order to ensure airtightness or improve adhesion to the housing.

  The sealing member 4 ensures the airtightness and dustproofness of the scale storage portion 1 a of the housing 1. In particular, it is effective for ensuring airtightness and dustproofness when removing the end blocks 2a and 2b. For this reason, the sealing member 4 is arrange | positioned so that it may be located between the scale storage part 1 and the end block storage part 1b, and forms both boundary. The outer shape of the sealing member 4 is generally rectangular like the housing, but preferably has a shape that conforms to the shape inside the housing 1. Furthermore, it is good to be a magnitude | size and shape which closely_contact | adhere to the inner surface of the housing 1 by slightly elastically or plastically deforming when mounted in the housing.

  Further, as shown in FIG. 8, a pair of seal lips 16a and 16b are arranged oppositely to the housing lower opening 15, and the opening 15 is elastically deformed and closed so that the encoder head column can slide. ing. Thereby, the airtightness and dustproofness of the scale housing portion together with the sealing member 4 are ensured, and the structure is such that oil, dust and the like do not enter.

  As shown in FIGS. 4 to 6, the sealing member 4 has a support column 41 and a support column 42, and is mechanically connected and fixed by a set screw 221 or the like corresponding to the stop hole hole 211 and the support column 214 of the terminal block 1 a, respectively. It has come to be. And it arrange | positions so that the block 1b for fixing may be pinched by the sealing member 4 and the terminal block 1a. That is, the sealing member 4 and the terminal block 1a are mechanically connected and fixed to the fixing block 1b.

  The material forming the sealing member 4 is preferably a material having elasticity to some extent because airtightness and dustproof properties are required, and a single material such as a resin material or an elastomer or a combination thereof is suitable. Further, although it is not necessary to consider the rigid surface, metals and alloys such as iron, stainless steel, brass, etc. may be used alone or in combination with the above materials depending on the application. Further, a ceramic or carbon material may be used in combination with the above materials.

  Other configurations of the linear encoder conform to a general linear encoder, and detailed description thereof is omitted. The linear encoder of the present invention can be applied to both a magnetic type and an inductive type, but an optical encoder is suitable for utilizing structural features excellent in airtightness and dustproofness.

  The optical encoder is, for example, a main scale provided with a grid (scribing line) so that a translucent part and a non-translucent part are arranged at a predetermined pitch on one surface of a reflective glass scale, and a transparent provided on the surface of the sensor It has an index scale with a grid (scribing line) on one surface of the glass so that the light transmitting and non-light transmitting portions are arranged at a predetermined pitch, and the main scale and the index scale are opposed to each other with a minute interval. The index scale grating is arranged so as to be tilted at a minute angle with respect to the main scale grating.

  When the grating moves by one pitch, the moire fringes are displaced by the interval of the stripes, and the movement amount within one pitch is accurately measured by reading the change of the transmitted light and reflected light of the slit within the interval. Will be able to.

  The sensor unit includes a sensor unit having an index scale and an optical sensor that are arranged opposite to the glass scale and provided with a lattice (engraving line), a guide roller for sliding the glass scale with less vibration. In addition to the above-described configuration, the main scale grating may be read without using moire fringes, and various known modes known as optical types can be selected.

  The encoder head 3 is attached to a movable part of a machine tool or the like, which is the object to be measured, and is connected to the sensor unit via a connecting column, and has a degree of freedom that can follow the irregular operation of the object to be measured to some extent It has a structure with The glass scale is mounted in the mounting groove inside the housing 1 by an elastic member or the like.

  The linear encoder 1 is attached to a fixed part 10 of a machine tool or the like by screwing the end blocks 2 at both ends of the housing 1 or the like, and an encoder head 3 is attached to a movable part 30 of a machine tool that is an object. It is attached. Then, the movement amount (displacement) of the movable portion 30 is detected as a relative movement amount between the glass scale and the sensor unit of the sensor unit moving along the scale.

  Next, the method for replacing the encoder head according to the present invention will be described. 9 to 13 are perspective views showing a procedure for replacing the encoder head.

  First, as shown in FIG. 9, the attachment screw 5 fixed to the attachment hole 5 of the encoder head 3 is removed, and the encoder head 3 is detached from the object 30 as the object to be measured so that it can freely move. .

  Next, as shown in FIG. 10, the encoder head 3 is moved to an unobstructed position so that the encoder head fixing portion of the object 30 having the encoder head fixing hole 31 is exposed to the outside and opened. To do. At this time, if the position of the housing can be measured by a displacement measuring device 19 such as a dial gauge as shown in FIG. 11, even if the housing 1 moves, the original state can be reproduced.

  Next, as shown in FIG. 12, the jig 33 is attached to the encoder head fixing portion of the object 30 to fix the housing 1. At this time, the locking portion 35 of the jig 33 is fitted and locked to the lower opening 15 of the housing, and the mounting holes 34 of the jig 33 formed at the same pitch as the encoder head fixing holes 31 are combined. Is fixed with screws 6. Thereby, the housing 1 can be firmly fixed to the object 30 by the jig 33, and even if the fixing block 2 is removed, there is no possibility that the housing 1 moves and the position is distorted.

  Although the jig 33 is formed in a block shape in the illustrated example, the jig 33 is not necessarily in a block shape, and may be a plate shape or another deformed shape. The jig 33 may be anything that can be fitted and locked to the housing lower opening 15 and can be attached to the encoder head fixing portion.

  Further, as shown in FIGS. 6 to 8, the terminal block 2a, the fixing block 2b, and the sealing member 4 are removed from the housing 1, and the encoder head 3 connected to the sensor unit is removed from the end of the housing. .

  Then, after performing necessary maintenance and repair, the encoder head 3 is housed in the housing 1 by the reverse process to the above, and the sealing member 4, the fixing block 2b, and the end block 2a are assembled and fixed. . Finally, the previous state is reproduced by removing the jig 3 and attaching the encoder head 3 to the encoder head fixing portion of the object 30. At this time, if necessary, the displacement measuring instrument 19 attached is confirmed to confirm that the position of the housing 1 is not out of order. If a displacement is recognized, the displacement measuring instrument 19 is adjusted from the value indicated by the measuring instrument 19 to restore the original value. Reproduce the state.

  As described above, since the fixed block 2 can be easily removed and the encoder head can be adjusted, repaired, and replaced, maintenance of the linear encoder becomes extremely easy. In addition, the time for stopping the apparatus to which the linear encoder is attached can be greatly shortened, and it is not necessary to move or disassemble the apparatus for removing the encoder, thereby greatly reducing the burden on the user side.

  The above method can be suitably used for the linear encoder having the end block structure of the present invention, but is not limited to this, and can be applied to any structure having the structure in which the encoder is similarly fixed by the end block. is there.

  The present invention is used for position information acquisition of a machine, a processing machine, etc., and is a linear encoder of a type that stores and reads a linear scale in a housing, whether it is an incremental type or an absolute type, optical, magnetic, It can be applied regardless of the induction type.

DESCRIPTION OF SYMBOLS 1 Housing 2 End block 2a Termination block 2b Fixing block 3 Encoder head 4 Sealing member 5 Fixing hole 10 Fixing part 11 Fixing opening 12 Fixing tool 15 Opening part 16a, b Seal lip 21 Attachment hole 30 Object (movable part)

Claims (2)

A housing for storing the scale;
An end block for fixing the housing to the object;
An encoder head replacement method in a linear encoder having an encoder head connected to a sensor unit that scans a scale and obtains position information,
a) Remove the encoder head fixed to the object from the object and move it,
b) Fix the object to which the encoder head was attached and the housing with a jig,
c) Remove the end block,
d) A method of replacing the encoder head, which removes the encoder head from the housing together with the detector unit.   The method of replacing an encoder head according to claim 1, wherein the jig is attached to an object using an encoder head attachment structure.

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