1. For the guide rails of different shapes, which appearances should be controlled separately from the straightness errors of the planes?
Answer: The common shapes of machine tool guides are rectangular guides and V-shaped guides. The horizontal appearance of the rectangular guide rail controls the straightness of the guide rail in the straight plane. Both sides of the rectangular guide rail control the straightness of the guide rail in the horizontal plane. As for the V-shaped guide rail, two oblique appearances are used to form the guide rail, so the two oblique appearances control both straightness errors in the straight plane and straightness errors in the horizontal plane together.
2.What are the common ways to check the straightness of the guide rail?
Answer: The common methods for checking the straightness errors of the guide rail are: research point method, flat-foot pull-meter comparison method, pad plug method, wire drawing method and spirit level method, optical leveler (autocollimator) method, etc.
3.What is the research point method?
Answer: When using a flat ruler to check the straightness error of the guide rail, evenly coat a thin layer of red sulphur oil on the surface of the track under test, cover the surface of the track with the flat ruler, and make short-term reciprocating movements with appropriate pressure. Ground points, and then remove the flat ruler to investigate the distribution of ground points on the surface of the inspected guide rails and the density of the least dense ground points. The research points are evenly distributed over the entire length of the guide rail, which indicates that the straightness error of the guide rail has reached the corresponding accuracy requirement of a flat ruler. This method is called research point method.
The ruler used in the research point method is a standard ruler, and its accuracy level is selected according to the accuracy requirements of the inspected guide rails, which is usually not lower than level 6. The length is not shorter than the length of the guide rail to be inspected (under the condition of low accuracy requirements, the length of the flat ruler can be 1/4 shorter than the guide rail).
4.Which types of guide rail straightness errors are applicable to the research point method?
Answer: When the straightness error of the guide rail is corrected by the scraping method, the research point method is mostly used. The grinding point method is often used for the inspection of short guides, because the flat ruler is easy to deform when it exceeds 2000mm, it is difficult to manufacture, and it affects the measurement accuracy. When scraping short guide rails, the straightness error of the guide rails is usually ensured by the accuracy of the flat rule. There is also a certain demand for the density of the research points within a unit area. It can be based on the accuracy requirements of the machine tool and the nature of the guide rail’s orientation and For the degree of importance, the separation rule is not less than 10 to 20 points per 25mm × 25mm internal research points (that is, the number of ideas in each square).
When using the research point method to check the straightness error of the guide rail, because it cannot measure the error value of the straightness of the guide rail, it is usually unnecessary to research the point method for final inspection when there is a level. However, it should be pointed out that, in the absence of measuring instruments (levels, optical levelers, etc.), the use of three square rulers produced by the mutual research method to check the square ruler can more effectively meet the inspection requirements of the straightness of the short rails of the machine tool.
5.The flat-foot pull-tab comparison method is suitable for measuring straightness errors on which planes of the guide rail?
Answer : The flat-foot pull-tab comparison method is usually used to check the straightness errors of the short guide rails in the straight plane and the horizontal plane. In order to improve the stability of the measurement reading, the length of the horn moving on the track under test usually does not exceed 200mm, and the touch surface of the horn and the track should be scraped with the track under test to make the touch outstanding, otherwise it will affect the measurement Accuracy.
(1) Checking method for straightness errors in a straight plane Place the flat-foot working surface horizontally and place it around the tested rail, the closer the interval is, the better, to reduce the influence of the rail distortion on the measurement accuracy. Put a scraped horn on the guide rail, and fix the dial indicator base on the horn so that the dial gauge probes top the appearance of the two feet of the ruler, and adjust the flat rule to make the dial gauge care about the appearance of the two feet of the ruler The readings are flat, then move the horn, and read the dial indicator value every 200mm. The maximum difference between the readings of the dial indicator is the straightness error in the entire length of the guide rail. When measuring, in order to avoid the effect of scratch points and make the reading accurate, it is best to pad a measuring block under the dial gauge probe.
(2) The method for checking the straightness error in the horizontal plane is shown in Figure 3-4. Place the working surface side of the flat ruler around the inspected guide rail, and adjust the flat ruler to make the dry submeters care about the readings on both sides of the ruler. The measurement method and the calculation error method are the same as above.
6.Which guide rails are suitable for checking the straightness error of the guide?
Answer : The plug method is suitable for viewing the polished and low-profile surface guides.
Rail, place a standard flat ruler on the plane guide rail to be inspected, at a distance of 2/9 • L from each of the two ends of the flat ruler, and support it with two contour blocks under the flat ruler. The gap between the working surface of the ruler and the surface of the measured rail. If the straightness of the horizontal lathe guide rail is (1000: 0.02) mm, a gauge block or feeler gauge equal to the thickness of the equal height block plus 0.02 mm cannot be plugged anywhere on the guide rail within a length of 1000 mm. Go in for a pass. When measuring the guide rail of a fine machine tool, a gauge block with higher accuracy should be selected so that the straightness error value of the guide rail can be measured more accurately.
This method can also replace the feeler gauge with a dial indicator, but it is necessary to increase the thickness of the contour block so that the dial indicator can enter the measurement.
7. What are the characteristics of the straightness error of the guide rail measured by the wire drawing method? What questions should I pay attention to during operation?
Answer: Use the tightened steel wire as the aspirating straight line to directly measure the straightness error line value of the various constituent surfaces on the guide rail. Like the comparison method with a flat-foot pull-down table, it is a line value measurement method.
This method can only check the straightness of the guide rail in the horizontal plane. Place a horn with a length of 500mm on the bed rail. A graduated reading microscope is mounted on the horn. The microscope lens should be aligned with the wire and it must be placed straight. At each end of the guide rail, a small pulley is fixed, and a wire with a diameter of less than 0.3 mm is used. One end is fixed on the small pulley, and the other end is suspended by a heavy hammer. The weight of the weight should be 30% to 80% of the wire breaking force. Then adjust the two ends of the steel wire so that when the microscope is at both ends of the guide rail, the steel wire coincides with the score line on the lens. Take down the reading on the movable reticle handwheel on the microscope.
Move the horn, investigate the microscope every 500mm, check whether the wire overlaps with the score line, and when it does not, adjust the handwheel on the reading microscope to make it coincide, and record the reading. Measure over the entire length of the rail and record the readings in order. Arrange the readings on the graph paper and draw a curve of the horn movement. The maximum coordinate difference between the motion curve at each 1000mm length and the line connecting the two ends is the straightness error at 1000mm length. If the formed curve is a convex or concave line, the coordinate difference between the most convex or concave point and the two ends is the straightness error over the entire length of the guide rail. If it is a wavy line (ie, points are separated on both sides of the abscissa axis), then the containment line method is used and the coordinate difference between the two parallel lines with the smallest interval is taken as the straightness error over the entire length of the guide rail.
8.What questions should be paid attention to when making the straightness error curve of guide rails?
Answer: When making the straightness error curve of the guide rail, the scale of the curve chart should be selected moderately. If the scale is too large, it is inconvenient to make and correct; if the scale is too small, it may be forbidden when calculating the straightness error of the guide rail. Recommended when measuring small and medium machine tools. The length of the 0-axis is 200mm, and the length of the long bed is 200 ~ 400mm. The special machine tools should not exceed 500mm. After the length of the 0-x axis is set, the scale of the x-axis can also be set. In practice, the 0-x axis represents the interval between the horns of the spirit level, which can be made from 1: 5 to 1:10, that is, the measurement interval of 200mm is indicated by 40 or 20mm. The z-axis and y-axis represent the accuracy error of the guide rail, which can be indicated from 1000: 1 to 2500: 1, that is, the accuracy error of 1 μm is expressed by coordinates of 1 to 2.5 mm. Extraordinarily fine machine tool guides (usually shorter) can take 5000: 1, that is, 1mm errors are indicated by 5mm.
For example, to measure a machine tool guide with a length of 1000mm, the specification of the spirit level used is 0.02 / 1000, and the length of the leveler horn is 200mm. When the level is placed on the 0 ~ 200mm section of the guide rail, the reading is zero. When the level is moved forward to the 200 ~ 400mm section of the guide rail in sequence, the bubble in the level moves forward by one division, which is a positive value, indicating this. The rail surface of the segment is skewed upward by 0.004mm; when the spirit level is moved to the segment of the rail surface of 400 ~ 600mm, if the bubble of the spirit level moves backward and returns to the zero position, this indicates that the rail surface of this segment is parallel to the rail surface of the segment of 0 ~ 200mm. Because the guide rail of 200 ~ 400mm section is skewed upward, the guide surface of section 0 ~ 200mm and the guide surface of section 400 ~ 600mm are parallel but not in the same plane. When the level is moved to the section of 600 ~ 800mm on the guide surface, the level of the level is The bubble in the device moves backward by one division, which is a negative value, which indicates that the plane of the guide rail in this section is skewed downward. In the end, a level of 800 ~ 1000mm is returned to the zero position, and the measurement is continued until the measurement of the entire guide rail is stopped. The curve formed by each line segment is called the guide rail straightness error curve (or the movement curve of the inspection tool).
9. What are the characteristics of using optical instruments to measure the straightness error of guide rails?
Answer: The principle of measuring the straightness error of a guide rail using a collimator and an active collimator (optical flattener) is based on the fact that the beam movement is straight. The advantages of using optical instruments for measurement are: (1) During the measurement, the accuracy of the instrument itself is less affected by external conditions (temperature, vibration, etc.), so the measurement accuracy is higher; (2) It can be used like a spirit level, and the measurement guide is straight. The straightness error in the plane (not equal to the level) can also replace the straightness error in the horizontal plane of the steel wire and the microscope measuring guide. Therefore, it has been widely used in the manufacture and repair of machine tools. However, for long rails measuring more than 10m, because the beam travels a long journey and the light energy is lost, the image is not clear enough to directly measure, and it is necessary to take length measurements in sections.
10.How to check the appearance of single rail distortion?
Answer: Regarding the appearance of each guide rail, in addition to the straightness requirements in the horizontal plane and in the straight plane, in order to ensure that the guide rail and moving parts cooperate well and improve the touch rate, it also needs to manipulate the distortion of the appearance of the guide rail. This requirement It’s especially important about large rails. During scraping, in order to measure the parallelism between the guide rails, the guide rails used as the reference measurement must avoid severe distortion.
How to check the appearance of single rails: V-shaped rails use V-level spirit horns, flat rails use flat horns, start from the random end of the rails, move the spirit level horns, and take readings every 200 ～ 5001Am. The algebraic difference is the distortion error of the guide rail. This error requirement is set in the machine tool accuracy specifications, and the first rule is in the scraping and grinding process.
11.What are the requirements for measuring the flatness of the machine tool table?
Answer: In the past, the inspection method for the flatness error of the machine tool table was followed by the “two-point method”, that is, the parallel flat ruler, dial indicator, contour block, frame level, etc. will be used along certain straight parts of the table. Measurement is understood as the maximum straightness error on any section. And it is inconsistent with the flatness definition rules in the national standard of shape and service. The current JB2670-82 “Examination Cases for Metal Cutting Machine Tools” states that the inspection and measurement of flatness errors are based on the appearance of the practical practice and the smallest interval. Spacing between parallel planes
From this definition, it can be seen that the orientation of the accommodation plane that is used as the basis of identification needs to be determined based on the principle of minimum conditions. Therefore, it is necessary to first grasp all the error conditions of the measured appearance, and then determine the evaluation standard according to the necessary principles. In this way, it was decided that the measurement must be divided into two processes, that is, the heights of several points on the practical appearance related to the desired aspiration plane (the measurement benchmark) were measured, and then the benchmark conversion was used to find the errors that fit the definition of the boundary. value.
12.How to operate and identify when measuring flatness errors with an indicator?
Answer: Use the indicator to measure the flatness error, and place the part to be measured on the flat plate with the support. The working surface of the flat plate is the measurement standard. When measuring, usually the first three points on the surface of the measured practice are adjusted to the same height as the flat plate (leveling), so the algebraic difference between the maximum reading and the minimum reading measured by the indicator is the plane identified by the three-point method. Degree error value. It is also possible to adjust the two ends of a diagonal line on the measured surface to be equal to the plate, and then adjust the two ends of the other diagonal line to be the same height as the plate, so the algebraic difference between the maximum and minimum readings measured by the indicator That is, the error value identified by the diagonal method. However, this leveling is difficult to compare. You can measure the measured appearance according to the necessary wiring and record the readings together. The algebraic difference between the maximum and minimum readings is usually used as the error value. If necessary, the data of each measurement point can be processed according to the minimum conditions to solve the error value.
13. What questions should I pay attention to when measuring flatness errors with a spirit level?
Answer: The measurement of flatness errors with a spirit level is based on the natural horizontal plane. The measured appearance should be adjusted to an approximate level first. Then place the spirit level on the bridge board, and then place the bridge board on the measured appearance. Measure the measured appearance point by point according to the necessary wiring, record the readings (number of divisions) of each measurement point together, and then convert the number of divisions into lines. value. According to the measured reading (line value), after data aluminium machining, the flatness error can be obtained. This method can be used to measure the flatness of large planes.
14.What questions should I pay attention to when measuring flatness errors with an autocollimator?
Answer: When measuring the flatness error with an autocollimator, the autocollimator is placed on a base other than the part under test, the reflector is placed on the bridge plate, and the bridge plate is placed on the surface to be measured. When measuring, you should first adjust the autocollimator to be approximately parallel to the measured surface. Then use the method of measuring straightness errors, wiring according to the meter, first measure the readings of each measuring point on the diagonal, and then measure the readings of each measuring point on another diagonal and other sections, and Convert these readings into line values.
According to the measured reading (line value), the intersection point of the two diagonal lines is used to determine the aspiration plane that conforms to the diagonal rule, and then the asymmetry plane is used to calculate the flatness error value. If necessary, the error value is further solved according to the minimum conditions. This method can be used to measure the flatness of large planes.
15. How to identify flatness errors when measuring with flat crystals?
Answer: Use an optical flat crystal to measure the small plane. When measuring, attach the flat crystal to the measured surface. If the measured surface is concave or convex, it will present a ring shape and a band. According to the ring shape and the number of bands and the half of the light wave, The product of the wavelengths indicates the flatness error.
If the stem and the stripe are not closed, the optical flat crystal and the measured appearance can be slightly skewed by an angle, so that an air wedge is formed between the two. The error value is obtained by multiplying the curvature of the stem and the band and the ratio between the adjacent two stems and the band by multiplying by half the wavelength. However, errors identified in this way are actually replaced by flatness errors with straightness errors.
In the past, only small planes could be measured with flat crystals. In recent years, there have been flat crystal stems and instruments. Using this instrument can also use flat crystal stems and instruments to measure larger planes.
16. How to check the straightness of the spindle axis of the horizontal milling head when the working table of the gantry milling machine moves?
Answer: The method of checking the movement of the working table of the gantry milling machine for the straightness of the spindle axis of the horizontal milling head is incorrect. During the inspection, the horizontal milling head is fixed at an orientation close to the work surface, the spindle sleeve is clamped, and the milling head with a rotatable viewpoint should be adjusted to the zero position. The workbench is moved to the base of the guide rail, that is, L / 2 away from the spindle axis, and a special slider is placed in the T-slot of the workbench, so that the slider flange abuts on the side of the T-slot of the base. An angle rod is fixed on the main shaft, so that the dial gauge head is on the side of the slider, and the reading in the table below is recorded. After the slider is not moved, after moving the length L of the worktable (the length of L is according to the different specifications of the machine tool and determined by the machine tool accuracy inspection specification), place the main shaft 180 ° so that the dial indicator contacts the side surface of the slider again for inspection. The maximum difference between the two readings of the dial indicator is the straightness error.
17. How to check the oblique circular runout error of the spindle taper?
Answer: Fix the lever dial indicator on the machine tool so that the dial indicator head is on the inside and outside surface of the taper hole of the spindle. The dial indicator head is straight on the inside and outside surface of the taper hole. Rotate the spindle to check that the dial indicator has the largest reading. The difference is the value of the oblique circle runout error. This inspection method is often used when inspecting the taper hole of the internal grinding head spindle.
18.How to check the radial circular runout error and oblique circular runout error of the spindle centering journal?
Answer: According to the requirements of application and planning, the spindle of the machine tool has various centering methods to ensure that the workpiece or tool is in a stable state when reversing. Therefore, the appearance of the centering journal is coaxial with the axis of reversal of the spindle. . The method for checking coaxiality errors is to measure the radial and oblique circular runout errors. Fix the dial indicator (micrometer used when measurement accuracy is required) on the machine tool, so that the dial indicator probe is on the surface of the spindle centering journal (if it is a tapered surface, the probe is straight on the tapered surface), and rotate Spindle inspection. The maximum difference between the dial indicator readings is the value of the radial and oblique circular runout errors of the centering journal. The measurement direction is the direction of the measured surface.
19. How to check the straightness error of the lathe slide in the straight plane?
Answer: Check the straightness error of the slide of the lathe in a straight plane: Swing the handle to move the rack to the base line, and place a spirit level on the slide near the knife rack and the bed rail equally. The slide is moved near the headstock to record a reading of the spirit level. In the future, the slide shall be recorded for every 500mm (or less than 500mm) of the slide toward the tailstock. The full stroke of the slide shall be recorded no less than four times.
Place the readings of the spirit level in sequence to draw the movement curve of the slide. The maximum coordinate value between the movement curve on the 1000mm stroke of the slider and the line connecting its two ends is the straightness error on the 1000mm stroke. The line connecting the two ends of the motion curve of the full stroke. The maximum coordinate value of the motion curve to the connection line is the straightness error on the full stroke.
Note: Before checking the accuracy of the machine tool, first adjust the device level of the machine tool. Place the bed inspection bridge on the bed rail, and place two levels on the bridge, one parallel to the rail and the other straight. Check whether the machine tool is level at both ends of the guide rail. Neither level readings agree to exceed the specified value. The rule for high-precision machine tools is (1000: 0.02) mm, and the rule for precision machine tools is (1000: 0.04) mm.
20.How to check the straightness error of the gantry planer moving in a straight plane?
Answer: The gantry planer’s workbench moves in a straight plane to check for straightness errors. A level is placed parallel to the direction of movement of the workbench at the base of the workbench. The working platform moves from one pole position to the other. The mobile working platform records the reading of the spirit level every 500mm (or less than 500mm). On the full travel of the workbench, record the readings of each position of the spirit level. Place the readings of the spirit level in order to draw the movement curve of the workbench.
The maximum coordinate between the movement curve over the stroke length of 1000mm and the two end points is the straightness error over the length of 1000mm.
Make a straight line containing motion curves parallel to each other, and the coordinate value between the two parallel lines with the smallest interval is the straightness error on the full stroke length of the guide rail.
21. How to check the straightness error of the cylindrical grinder table moving in a straight plane?
Answer: Check the straightness of the cylindrical grinder table moving in a straight plane. Put a bridge board attached to the random bed at the base of the workbench, or a dedicated bridge board that is self-contained (only used for inclined tables, and the platform does not need bridges). Place a spirit level parallel to the direction of the bridge base and the movement of the workbench. Move the worktable, record readings every 250mm (check the short bed at the two ends of the maximum grinding length and the three directions of the base), place the readings of the level in sequence, and draw the movement curve of the worktable. The maximum coordinate value between the motion curve on the 1000mm length and the line connecting the two ends is the straightness error on the 1000mm length.
Make a straight line containing movement curve parallel to each other, and the coordinate value between the containing lines is the straightness error value over the full length of the guide rail.
22.How to check the straightness error of the lathe slide in the horizontal plane?
Answer: If the stroke of the lathe slide is less than 3000mm, the straightness error of the lathe slide in the horizontal plane can be checked by using a long cylindrical check rod. Between the front and rear centers, a long cylindrical inspection rod is tightened, and the dial indicator is fixed on the slide plate, so that the dial indicator head is on the side bus of the inspection rod. Adjust the tailstock so that the dial indicator reads flat on both ends of the check rod. Move the slide and check on the full stroke of the slide. The maximum difference between the dial indicator on the 1000mm stroke is the straightness error.
When the slide stroke is greater than 3000mm, use a tensioning wire parallel to the bed rail, and use a microscope (optical flattener) to check.
23. How to check the straightness error of the long bed operation platform or slide in the horizontal plane?
Answer: When the travel of the working table such as gantry planer, gantry milling machine, horizontal milling and boring machine is more than 2000mm, and the slide stroke of horizontal lathe, lead screw lathe and other is more than 3000mm, because the flat rule of 2000mm or more is easy to deform, and the inspection rod above 2000mm There are also many difficulties in manufacturing, so tools such as wire and microscope should be used for inspection. The inspection method is the same as the inspection method for the straightness error of the guide rail, refer to the inspection method for checking the straightness error of the guide rail in the horizontal plane by pulling the wire.
When conditions permit, you can also use an optical leveler to check. Place the optical leveler on one end of the machine tool and the mirror on the slide or the work surface. Adjust the leveler and the mirror at the two extreme positions of the travel. The bright cross image of the collimator coincides with the alignment of the movable reticle. Every time the worktable moves 500mm, take a reading and make a record. Place the readings in order to draw the movement curve of the worktable, and then calculate the error value over the length of 1000mm and the total length of the stroke.
24. How to check the tilt error when the slide is moving?
Answer: Check the tilt error when the slide is moving. Place the spirit level on the dovetail guide of the slide close to the blade holder, straight to the bed rail (that is, the direction of the slide travel). Move the slide, record a reading every 250mm (or 500mm, or less), check on the full stroke of the slide. The maximum algebraic difference between the reading of the spirit level on the 1000mm stroke and the full stroke is the tilt error. Inclination errors are indicated as slope or angular values.
25. How to check the tilt error when the workbench is moving?
Answer: Check the inclination error when the worktables such as cylindrical grinder, thread grinder, broach grinder, planer and gantry milling machine are moved. At the worktable base, place a spirit level straight in the direction of the worktable. The spirit level should be placed on a special pad). Move the workbench and record a reading every 250mm (or 500mm or less). The short bed should record at least three readings on the full travel of the workbench. The maximum algebraic difference between the reading of the spirit level on the 1000mm stroke and the full stroke is the tilt error when the worktable is moved.
26. How to check the tilt error when the beam moves?
Answer: To check the tilt error when the beam is moving, place a spirit level parallel to the beam at the base orientation of the beam guide. Move the beam, record a reading every 500mm (or less than 500mm), and record at least 3 readings on the full travel of the beam. When inspecting the full travel of the beam, two straight tool holders (or milling heads) should be moved to a symmetrical position on the beam. The moving direction of the beam can only be from bottom to top, and cannot be reciprocated.
This method is mostly used to check the tilt error when the beams such as gantry planer, gantry milling machine, and vertical lathe are moved.
27. Which machine tools have higher positioning accuracy requirements? What should I usually check?
Answer: The positioning accuracy of the coordinate boring machine is relatively high, so you should check the positioning error of the working table or the spindle box after moving the coordinate positioning.
The positioning systems of various domestic coordinate boring machines include optical systems and mechanical systems (that is, lead screws and calibration rulers). Although the positioning system used is different, the measurement method for positioning errors is the same. On the machine tool table, place a fine ruler along the longitudinal movement direction (the ruler accuracy of the ruler should be accompanied by an error check table, and the test accuracy should be within 0.0005mm). The ruler should be placed at the base of the workbench and the height should be The maximum distance from the worktable to the end face of the straight spindle is l / 3 ~ l / 2. The reading microscope (with a reading accuracy of 0.001 ~ 0.002mm) is fixed on the spindle sleeve, so that the microscope can clearly observe the engraved lines on the ruler, and check the movement of the work table over a regular length (usually every rule Move the 10mm reading once). The table should be clamped when reading. The positioning error is the most algebraic difference in the practical difference of the readings when the two positionings are intentional.
28. How should the indexing indexing error be checked?
Answer: The indexing indexing error is fixed. The standard indexing plate is fixed on the main axis of the indexing head. The bases should be kept coincident. The reading microscope is fixed on the support of the inspection plate. Determine the starting position of the handle, and align the reading microscope and index dial to zero. Then make the indexing head take a reading every 90 ° and make a record.
When the optical indexing head is used for comparison inspection, a two-end inspection rod with a Morse taper is inserted into one end of the optical indexing head main shaft cone hole, and the other end is closely inserted into the inspected indexing head main shaft cone hole. In order to connect the two indexing heads into one. When the tested index head and the optical index head’s main shaft base are not the same height, the leveling should be adjusted. Disengage the manual indexing organization of the optical indexing head, roll the handle of the indexing head to be inspected, and make the indexing head to be rolled. After passing the inspection rod, the optical indexing head can be moved. When the tested indexing head is determined to be in the starting position, note the optical indexing head and the indexing head to roll. When the tested indexing head is judged to be in the starting position, record the reading of the starting position of the optical indexing head.
(1) When the errors of the indexing plate and the indexing worm are not considered, the inspection method and the indexing error calculation are as follows:
The transmission system of the indexing system is that when the indexing head handle rotates n times, the main shaft rotates once, that is,
n = z2 (the number of teeth of the indexing worm) ÷ z1 (the number of teeth of the indexing worm)
Usually the indexing head indexing worm gear number z2 = 40, the worm head number z1 = 1. Therefore, each time the handle rotates once, the theoretical viewpoint that the main axis of the indexing head turns is 360 ° / 40 = 9 °. After checking the positioning, record the reading of the standard indexing disk (or optical indexing head) once. Each time the handle rotates one revolution, the difference between the theoretical viewpoint at which the main shaft should turn and the actual reading in the optical instrument is the indexing error at each revolution of the indexing worm. During one revolution of the main shaft, 40 indexing error values can be obtained, and the maximum algebraic difference between the error values is the maximum indexing error when the indexing head rotates one revolution.
During the inspection, the main shaft should be rotated clockwise for one round to check, and then the main shaft should be rotated counterclockwise for one round to check again.
(2) When thinking about the errors between the indexing plate and the indexing worm, the inspection method and the indexing error calculation are as follows: Make the indexing worm handle turn not by one revolution but by an angle of α. This α angle is also equivalent to 1 / z rotation of the handle, that is, α = 360 ° / z, z is an integer of 8-12, and it is determined by the indexing transmission until the number of holes on the original indexing disk of the indexing head to be inspected. During the inspection, when the handle is turned through the α angle (ie, 1 / z week), a reading of the standard index plate (or optical index head) is recorded. Record and calculate according to the theoretical rotation angle and practical reading of the main axis of the indexing head. The maximum and minimum algebraic difference between them is the maximum indexing error of the worm during one revolution.
When checking, make the indexing handle roll one clockwise and one counterclockwise for one check each time. The indexing error value of the indexing system is the sum of the maximum indexing error when the spindle rotates for one revolution and the maximum indexing error when the worm rotates for one revolution.
29.How to check the indexing error of the reverse operation table with the Happa check fixture?
Answer: Normally, the reversing workbench is an accessory of the milling machine, and the indexing accuracy is low. Therefore, you can use the eight-way inspection tool for inspection. The diameter of the circumscribed circle of the Bafang gauge is 250mm. The positioning mandrel of the octagonal inspection tool is closely penetrated into the taper hole of the operation table to ensure that the inverted base of the operation table coincides with the circular base of the octagonal test tool.
Fix the worktable to be inspected on the inspection plate, and press the flange on the dial indicator base against the guide groove on the inspection plate. There can be no ruler to replace the guide groove.) On one side of the tool, move the dial indicator base along the guide groove so that the dial indicator reads the same at both places (by rolling the worm handle to adjust). Then turn the working table over 45 ° (ie 360 ° / 8), check the dial indicator over the full length of the other side, and check each side in turn. The maximum difference between the two readings of the dial indicator on either side is the indexing error.
This method is used when the measurement accuracy is not high (the error is in the range of 4 ′ ~ 8 ′).
30.How to check the indexing error of the reverse operation table with a fine horizontal turntable?
Answer: Checking the indexing error of the reversing operation table with a fine horizontal turntable is more convenient than theodolite measurement, but it is more convenient than the theodolite, the operation is simple and the power is high. The method: place the fine turntable on a flat plate or a machine tool workbench, and check with a spirit level to make the turntable in a horizontal state. Stack the inspected reversing operation table on the fine rotating table, and use a dial indicator to find the parallelism of the two revolving table operating surfaces (flattening with pads when not parallel), and make the positioning holes of the two reversing tables reverse the base line Overlap, fix the two turntables into one with screws.
Fix a positioning block on the turntable surface to be tested, and fix the dial indicator on the flat plate (when checking on the machine table, you can fix the dial indicator on the machine tool spindle), so that the dial indicator head is positioned The side of the block. Adjust the fine turntable, the turntable to be checked and the dial indicator so that the cursor marks of the two turntables and the pointer of the dial indicator are at the zero position. First, roll the handwheel of the reversed worktable to be inspected, and rotate the worktable clockwise by a certain point of view (integer value), and then roll the handwheel of the fine turntable to turn the worktable to be rotated counterclockwise with the fine turntable. When you turn to the side of the positioning block and touch the dial gauge probe and the dial indicator returns to the zero position (starting position), the fine turntable stops scrolling. At this time, the engraved line readings of the two turntables are recorded, and the difference between the two is the indexing error of the reverse turntable being checked.
In this way, inspections should be carried out every 10 °, 5 ° and 1 °.