9 inspection knowledge of the accuracy of each part of the machine tool
9 inspection knowledge of the accuracy of each part of the machine tool
1.How to check the repeated positioning errors of the rapid-feeding tissue of the cylindrical grinder wheel frame?
Answer: Cylindrical grinder wheel frame feeds the tissue quickly and repeatedly to check the positioning error. The micrometer is fixed on the machine table, the wheel frame is in the feeding direction, so that the micrometer's probe head is on the axis of the wheel frame near the wheel. , The grinding wheel rack feeds at a rapid speed, 10 times in succession, and the maximum difference between the micrometer readings is its repeated positioning error.
2.How to check for repeated positioning errors of the shovel lathe tool post's operation stroke?
Answer: The inspection method for the repeated positioning errors of the shovel lathe tool holder's operation stroke: Fix the dial indicator on the slide plate at the back of the tool holder, make the probe head on the side of the tool holder, and roll the drive shaft by hand to make the tool holder work. Reciprocate and check again. The tool post reciprocates 10 times, and the maximum difference between the dial indicator readings is the repeated positioning error.
3.What are the main factors that affect the accuracy of workpiece machining in machine machining?
Answer: In machine tool machining, the factors that affect the accuracy of workpiece machining are mainly the following aspects:
(1) The shape of the tool is wrong and the equipment on the machine tool is wrong.
(2) The equipment on the machine tool is wrong.
(3) There are errors in the machining principle of the cnc machine tool.
(4) During the cutting process, the vibration, elastic deformation, thermal deformation and tool wear of the machine-tool-workpiece system.
(5) A few errors of the machine tool.
(6) Transmission error of the machine tool transmission chain.
4.How to improve the accuracy of the machine tool transmission chain?
Answer: When designing the machine tool, improving the accuracy of the machine tool transmission chain can be started from the following aspects:
(1) Try to reduce the number of transmission elements in the transmission chain to reduce the origin of errors.
(2) In the transmission chain, choose to reduce the speed as much as possible from the beginning to the end, and invent the maximum transmission ratio for the final transmission pair (increasing the number of worm gears, reducing the number of worm heads, reducing the number of lead wires and reducing the wire Pitch).
(3) Try not to use helical gears, bevel gears or clutches near the final transmission pair.
(4) Put the AC gear as far as possible in front of the final drive pair.
(5) Try to choose gear pair transmission with a transmission ratio of 1: 1 to compensate for its transmission errors.
(6) Improve the accuracy of transmission components.
(7) Improve the equipment accuracy of transmission components and use error compensation methods in equipment.
(8) Use error proofing equipment.
Repairing or modifying the machine tool is different from the new design. It is difficult to improve the accuracy of the drive chain by changing the structure of the drive chain of the machine tool (such as reducing the number of transmission components, selecting a lower speed from the automatic parts to the end), or improving the accuracy of the components. The practicable method is to improve the accuracy of the transmission equipment. Selecting the corresponding compensation method for errors and installing error correction equipment can improve the accuracy of the machine tool one step in the repair operation, or make it less severe when the accuracy loss is not severe. Rehabilitation.
5. Which machine tools must be checked for transmission error? What are the inspection methods?
Answer: Any machine tool that consists of a transmission chain to process gears and threads, in order to obtain accurate tooth profile, pitch, and tooth accuracy, it must ensure that the transmission chain has a certain degree of accuracy.
There are two methods for checking the transmission errors of the machine tool transmission chain: indirect method and direct method:
(1) The indirect method is to process a product, such as a gear or a screw, according to the rules of the machine tool manual, measure the workpiece, and check the quality of the workpiece to determine whether the transmission error of the machine tool transmission chain can process the workpiece with the required accuracy level. . This method reflects the inductive errors of the construction process, including both the transmission errors of the machine tool transmission chain and the errors of other elements.
(2) Direct method There are two kinds of static measurement method and dynamic measurement method.
6.How to perform static inspection of gear hobbing machine indexing transmission errors?
Answer: In the vertical gear hobbing machine accuracy inspection, the inspection of indexing transmission errors:
First, equip the machine tool with indexing hanging wheels and adjust the indexing chain so that the number of indexing teeth is equal to the number of teeth of the indexing worm z.
A gauge index plate is mounted on the hob spindle, and a reading microscope is mounted on the column to determine the rotation viewpoint of the gauge index plate (ie, the hob spindle).
Install a theodolite (or optical goniometer) on the workbench, a collimator (ie, a parallel light pipe) on the bracket outside the machine tool, or a calibration hairline can be hung in the distance to determine the rotation of the workbench Viewpoint.
When the hob main shaft machining rotates for one revolution, the indexing worm wheel of the work table should theoretically rotate 360 ° / z. With each revolution of the hob main shaft, the theodolite will return to its original orientation. According to the reading of the theodolite, the practical rotation point of the work table is determined.
Check the working table forward and reverse. The difference between the practical rotation viewpoint and the theoretical rotation viewpoint of the worktable is the indexing transmission error of the indexing transmission chain of the machine tool.
7. How does the hobbing machine dynamically measure transmission errors?
Answer: Like checking the gear hobbing machine, the transmission error of the hobbing machine is dynamically measured according to the rolling principle. The hob axis of the adjusting hob holder is parallel to the axis of the worktable. On the hob shaft, the device conflicts a disc. On the working table, a concentric device is provided with a fixed disc with a mandrel, and an empty disc is set on the mandrel. The diameter ratio of the two conflicting discs is equal to the transmission ratio between the hob shaft and the work table. When the conflict disk rolls, it relies on the conflict force to move the conflict disk to form a standard comparison organization. When there is no transmission error between the hob shaft and the worktable transmission chain, the conflicting disk and the fixed disk can be reversed synchronously; but when a transmission error occurs between the transmission chain, the fixed disk cannot be reversed severely synchronously with the conflicting disk. The device has an inductive sensor head between the fixed disk and the conflict disk, which can convert asynchronous reversal into electrical signals, and output, expand, rectify and record the electrical signals. According to the recorded curve, make a "qualitative" and "quantitative" analysis of the transmission errors of the transmission chain to determine the size of the transmission errors and the origin of the errors.
8.How to perform dynamic measurement on the transmission errors of horizontal lathes and fine screw lathes?
Answer: Dynamic measurement of transmission errors of horizontal lathes and fine screw lathes. Fine nuts, dial gauges, and standard screw inspections can be selected according to the rules of professional accuracy standards for machine tools.
Between the front and back centers, a standard screw with a fine nut is tightened. The nut should cooperate with the standard screw accurately (or equipment with adjusting gaps), and the standard screw is rolling. The nut can only be used in the axial direction. Move without scrolling.
Fix the dial indicator on the slide plate so that the dial indicator head is on the end face of the nut. The ratio between the standard screw pitch and the machine screw pitch is used as the transmission ratio of the spindle to the transmission screw.
Close the opening and closing nuts of the machine tool, start the machine slowly, and check it once at 25mm, 100mm, and 300mm lengths. The maximum difference in the dial indicator reading is the drive error.
9.How should I check the turret lathe for repeated positioning errors?
Answer: The turret lathe is turned back to repeat the positioning error check. A check rod is inserted tightly into the east and west holes of the return head. Base L (L is subject to inspection normative rules), then exit and turn back.
Roll the head back 360 °, push it to the original position, and measure again, repeat the measurement 5 times. The dial indicator measures the maximum difference between the readings five times in a row, which is the repeated positioning error. Look back at every hole.
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