A grating increment test fixture for a linear encoder

Abstract

The utility model discloses a grating increment test fixture for linear encoder relates to linear encoder test technical field, including jig base, slide rail guide rail, sliding table, encoder base, spacing iron piece, encoder clamp, the recess of placing grating ruler, spacing screw and the recess of placing encoder, the slide rail guide rail is fixed in jig base middle part through screw, and sliding table is fixedly connected with spacing iron piece through screw, and sliding table realizes unidirectional translation through spacing iron piece and slide rail guide rail cooperation, the utility model has the advantageous effects that: through the structure that spacing iron piece buckles slide rail guide rail, and sliding table translation has no radial shaking, and the relative clearance tolerance of grating ruler and encoder reading head can be controlled, and the stroke error of sliding table multiple reciprocating motion is small, and the test precision is far more than traditional linear motor module, and the recess of placing encoder is positioned and installed fast to encoder reading head, and grating ruler is directly fixed through the recess of placing grating ruler, and it is not necessary to repeatedly debug, and the test period is short.

Description

Technical Field

[0001] This utility model relates to the field of linear encoder testing technology, specifically a grating increment testing fixture for linear encoders. Background Technology

[0002] Encoders are key testing components in industrial automation, mainly divided into optical grating type and magnetic grating type. Optical grating encoders further include incremental and absolute types. Their accuracy directly affects the operating accuracy of automated equipment. However, existing technologies have significant shortcomings in the testing and calibration of linear encoders. Temporarily constructed high-precision reference systems (such as testing devices based on marble platforms and laser interferometers) require reassembly and debugging each time. Laser optical path collimation requires high operator skills and is significantly affected by temperature (±0.1℃ change affects accuracy), humidity, air pressure, and airflow interference, requiring continuous compensation. This cannot meet the needs of batch and rapid testing on the production line. The test device based on the linear motor module has low reliability due to the backlash of the module itself, the thermal expansion error of the lead screw, the poor compatibility of the installation fixture, the difficulty in installing the grating ruler, and the decrease in stability caused by thermal deformation after long-term testing. Rotary encoder testing platforms need to convert rotary motion into linear motion through transmission mechanisms such as ball screws and racks. Backlash, pitch error, and elastic deformation are easily introduced in the intermediate links, making them unsuitable for the testing and calibration requirements of linear encoders.

[0003] Therefore, developing a linear encoder grating increment test fixture that is structurally stable, easy to install, and has controllable accuracy has become an urgent need to improve testing efficiency and accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a grating increment test fixture for linear encoders to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a grating increment test fixture for a linear encoder, comprising a fixture base, a slide rail, a slide table, an encoder base, a limiting block, an encoder clamp, a groove for placing a grating ruler, a limiting screw, and a groove for placing an encoder. The slide rail is fixed to the middle of the fixture base with screws, and the slide table is fixedly connected to the limiting block with screws. The slide table can move in one direction through the cooperation of the limiting block and the slide rail. The encoder base is fixed to the fixture base with screws, and the encoder fixture is fixed to the encoder base with screws. The groove for placing the grating ruler is opened on the upper surface of the slide table, and the groove for placing the encoder is opened on the upper surface of the encoder fixture. There are two limiting screws, which are respectively installed on the fixture base at both ends of the corresponding slide rail travel.

[0006] Preferably, there are four limiting iron blocks in total, which are symmetrically fixed to the bottom of the slide table in two groups. The inner side of the limiting iron blocks is provided with an inner buckling structure, which is tightly engaged with both sides of the slide rail guide, with a fitting gap of 0.003 to 0.005 mm.

[0007] Preferably, the machining accuracy of the groove for placing the grating ruler and the groove for placing the encoder is IT7 grade, and the parallelism error of their center lines is ≤0.01mm / m.

[0008] Preferably, the stroke error of the slide table during multiple reciprocating motions is ≤0.03mm, the relative gap tolerance between the grating ruler and the encoder reading head is 0.01±0.002mm, and the fixture shows no significant performance degradation when tested in an environment with a temperature of -10~50℃ and a humidity of 10%~90%RH.

[0009] Compared with the prior art, the beneficial effects of this utility model are: through the structure of the limiting iron block in the inner slide rail guide, the slide table moves without radial wobbling, the relative gap tolerance between the grating ruler and the encoder reading head can be controlled, the stroke error of the slide table in multiple reciprocating movements is small, and the test accuracy is far superior to that of traditional linear motor modules; the encoder reading head is quickly positioned and installed through the groove for placing the encoder, and the grating ruler is directly fixed through the groove for placing the grating ruler, without the need for repeated adjustments, and the test cycle is short; Strong environmental adaptability: The fixture base is made of tempered steel, and the slide rail and slide table have no transmission parts that are easily affected by the environment, so the test performance is not significantly reduced; the limit screws at both ends of the slide rail travel can effectively prevent the slide table from flying out of the overtravel range, avoid damage to the grating ruler or encoder reading head during the test, and ensure the consistency of the travel in each test. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the mating structure between the slide table and the slide rail of this utility model; Figure 3 This is a schematic diagram of the encoder clamp part of this utility model.

[0011] In the diagram: 1. Fixture base; 2. Slide rail; 3. Slide table; 4. Encoder base; 5. Limiting block; 6. Encoder clamp; 7. Groove for placing the grating ruler; 8. Limiting screw; 9. Groove for placing the encoder. Detailed Implementation

[0012] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0013] Please see Figure 1-3 This utility model provides a technical solution: a grating increment testing fixture for linear encoders. The fixture includes a base 1, a slide rail 2, a slide table 3, an encoder base 4, a limiting block 5, an encoder clamp 6, a groove 7 for placing a grating ruler, limiting screws 8, and a groove 9 for placing the encoder. The slide rail 2 is fixed to the middle of the fixture base 1 with screws. The slide table 3 is fixedly connected to the limiting block 5 with screws, and the slide table 3 achieves unidirectional translation through the cooperation of the limiting block 5 and the slide rail 2. The encoder base 4 is fixed to the fixture base 1 with screws, and the encoder clamp 6 is fixed to the encoder base 4 with screws. The groove 7 for placing the grating ruler is opened on the upper surface of the slide table 3, and the groove 9 for placing the encoder is opened on the upper surface of the encoder clamp 6. There are two limiting screws 8, which are respectively installed on the fixture base 1 at both ends corresponding to the stroke of the slide rail 2. The limiting block... Four limit blocks 5 are symmetrically fixed to the bottom of the slide table 3 in two groups. The inner side of the limit block 5 is provided with an inner buckling structure, which is tightly fastened to both sides of the slide rail 2 with a fit clearance of 0.003~0.005mm to prevent the slide table 3 from wobbling left and right when it moves horizontally. The machining accuracy of the groove 7 for placing the grating ruler and the groove 9 for placing the encoder is IT7 grade, and the parallelism error of their center lines is ≤0.01mm / m to ensure the installation and positioning accuracy of the grating ruler and the encoder reading head. The stroke error of the slide table 3 during multiple reciprocating movements is ≤0.03mm, the relative clearance tolerance of the grating ruler and the encoder reading head is 0.01±0.002mm, and the performance of the fixture is not significantly reduced when tested in an environment with a temperature of -10~50℃ and a humidity of 10%~90%RH.

[0014] Specifically, when using this utility model, during assembly, first fix the slide rail 2 to the middle of the fixture base 1 with M6 hexagon socket screws (50mm spacing) to ensure that the center line of the slide rail 2 is parallel to the length direction of the fixture base 1. After installation, use a dial indicator to check the straightness of the slide rail 2, and the error is ≤0.01mm / m. Next, the four limiting iron blocks 5 are divided into two groups (two in each group) and fixed to the bottom of the slide table 3 with M4 screws. Then, the slide table 3 is installed on the slide rail 2. The inner buckling structure of the limiting iron blocks 5 and the matching gap between the two sides of the slide rail 2 are adjusted to 0.003~0.005mm to ensure that the slide table 3 moves smoothly along the slide rail 2 without radial shaking. Then, limit screws 8 (M8 adjustment screws) are installed on the jig base 1 at both ends of the travel of the slide rail 2 (10mm from each end of the slide rail). The limiting effect is tested by manually pushing the slide table 3 to ensure that when the slide table 3 moves to the limit position, the limit block 5 and the limit screw 8 flexibly abut (without rigid impact). Finally, fix the encoder base 4 to the fixture base 1 with M6 screws (located on one side of the slide rail 2, 30mm from the center line of the slide rail). Then fix the encoder clamp 6 to the encoder base 4 with M4 screws. Use a right-angle ruler to correct the verticality of the encoder clamp 6 to ensure that the parallelism error between the center line of the groove 9 where the encoder is placed and the center line of the groove 7 where the grating ruler is placed is ≤0.01mm / m.

[0015] During testing, the grating ruler to be tested is placed in the groove 7 on the slide table 3, and the grating ruler is fixed by the elastic pressure plate to ensure that the grating ruler does not move. Place the encoder reader into the encoder mounting groove 9 on the encoder fixture 6, with the detection surface of the reader facing the scale line surface of the grating ruler. Measure the gap between the two using a micrometer to ensure that the gap is 0.01±0.002mm. The slide table 3 is manually or driven by an external drive mechanism (such as a stepper motor) to reciprocate along the slide rail 2. The incremental signal output by the encoder read head is recorded by a data acquisition device and compared with the actual stroke of the slide table 3 (which can be calibrated by a laser interferometer) to achieve the accuracy test and correction of the encoder. During the test, the limit screw 8 prevents the slide 3 from exceeding its travel range, and the cooperation between the limit block 5 and the slide rail 2 ensures that the relative position of the grating ruler and the reading head remains stable, avoiding test errors caused by shaking.

[0016] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A grating increment testing fixture for a linear encoder, characterized in that: It includes a fixture base (1), a slide rail (2), a slide table (3), an encoder base (4), a limiting block (5), an encoder clamp (6), a groove for placing a grating ruler (7), a limiting screw (8), and a groove for placing an encoder (9). The slide rail (2) is fixed to the middle of the fixture base (1) by screws. The slide table (3) is fixedly connected to the limiting iron block (5) by screws. The slide table (3) and the slide rail (2) cooperate to achieve unidirectional translation through the limiting iron block (5). The encoder base (4) is fixed to the fixture base (1) by screws. The encoder clamp (6) is fixed to the encoder base (4) by screws. The groove (7) for placing the grating ruler is opened on the upper surface of the slide table (3). The groove (9) for placing the encoder is opened on the upper surface of the encoder clamp (6). There are two limiting screws (8), which are respectively installed on the fixture base (1) at both ends of the corresponding slide rail (2) stroke.

2. The grating increment test fixture for a linear encoder according to claim 1, characterized in that: There are four limiting iron blocks (5) in total, which are symmetrically fixed to the bottom of the slide table (3) in two groups. The inner side of the limiting iron block (5) is provided with an inner buckling structure, which is tightly fastened to both sides of the slide rail (2) with a fitting gap of 0.003 to 0.005 mm.

3. A grating increment testing fixture for a linear encoder according to claim 1, characterized in that: The machining accuracy of the groove (7) for placing the grating ruler and the groove (9) for placing the encoder is IT7 grade, and the parallelism error of their center lines is ≤0.01mm / m.

4. The grating increment test fixture for a linear encoder according to claim 1, characterized in that: The travel error of the slide (3) during multiple reciprocating motions is ≤0.03mm, the relative clearance tolerance between the grating ruler and the encoder reading head is 0.01±0.002mm, and the fixture shows no significant performance degradation when tested in an environment with a temperature of -10~50℃ and a humidity of 10%~90%RH.

Images