Hole series machining of the hottest boring machin

2022-07-23
  • Detail

Boring machine hole system processing

1. Structural features of box parts

answer: box parts are the basic parts of the machine, so the overall dimensions are large; The structural shape of box type parts is complex, and datum planes, holes or hole systems with high accuracy requirements are often set; The interior of box parts is cavity shaped, and many reinforcing ribs, concave surfaces, lugs, etc. are distributed, which increases the complexity of the shape; There are many machining surfaces of box parts, and the machining amount is large. The mutual position accuracy between the machining surfaces is required to be high

2. What are the basic technical requirements for the machined surface of box parts? The dimensional accuracy, geometric accuracy and mutual position accuracy of the support holes on the box parts are out of tolerance. What is the impact on their service performance

answer: the basic technical requirements for the machined surface of box parts are:

(1) requirements for the dimensional accuracy and geometric accuracy of support holes

(2) requirements for dimensional accuracy of hole spacing and mutual position accuracy between support holes

(3) requirements for shape accuracy and mutual position accuracy of main planes

(4) surface roughness requirements for machined surfaces

the dimensional accuracy and geometric accuracy of the bearing hole on the box part are out of tolerance, which will cause poor matching between the bearing and the box hole and cause vibration and noise. The support corrects the data. If the hole spacing dimension accuracy and mutual position accuracy between the holes are out of tolerance, the assembly and gear meshing accuracy will be affected, and noise and vibration will be generated. The coaxiality of the coaxial hole system is out of tolerance, which will not only bring difficulties to the assembly of the shaft in the box, but also make the operation of the shaft worse, the bearing wear is intensified, the temperature is increased, the accuracy and normal operation of the machinery and equipment are affected, and the service life is reduced

3. What are the main factors that should be considered when selecting the rough datum for machining box parts? Which surface should be selected as the coarse datum in general? Why

answer: when selecting the rough datum for machining box parts, it should be considered to ensure that there is sufficient machining allowance for each machined surface; Ensure that the machining allowance of the main support holes is uniform, and that there is enough space in the inner cavity, so as to ensure that the inner cavity wall will not collide with the transmission parts after assembly, and properly take into account the overall dimension of the box

when machining box parts, the important support holes on the box are usually selected as the rough datum. The purpose is to ensure that the important support holes on the box have sufficient and uniform machining allowance, which is conducive to the machining of the hole system of the whole box

4. Try to analyze why the assembly datum on the box parts is usually selected as the positioning precision datum during machining

answer: because the assembly datum such as the bottom plane and side plane used to connect the body parts on the box has certain position requirements with other machining surfaces, holes or hole systems on the box, and is often the design datum of the main support holes in the machining surfaces, holes or hole systems. Therefore, starting from the principle of datum coincidence, selecting these surfaces as positioning precision datum can reduce the datum non coincidence error; Based on the principle of unified datum, it can also reduce the cumulative clamping error caused by multiple conversion of positioning datum, reduce the quantity of flammable and highly corrosive materials of fixtures, cutters and measuring tools, and reduce the production cost. In addition, since the assembly benchmark of the box is generally the bottom plane with large area and the side plane with good guidance, the positioning accuracy is high, and it is stable and reliable after clamping. In addition, it is convenient to clamp and adjust the tool and observe during machining, so it is widely selected as the positioning precision benchmark during machining

5. What are the methods for boring coaxial hole system

answer: in case of batch or mass production, the boring die method is often used for boring the coaxial hole system. In case of single piece or small batch production, the boring method and turn around boring method can be used. The boring method can be divided into several forms, such as overhanging boring, boring after the boring bar is supported by the guide bearing sleeve, and boring by the combination of the long boring bar and the tailstock

6. What are the process characteristics of turning around boring method for machining coaxial holes on horizontal boring machine

answer: the turn around boring method can boring the coaxial holes from both ends of the hole wall. Its characteristics are that the boring bar has short extension and good rigidity. Larger cutting parameters can be selected during boring to shorten the maneuvering time. However, since the holes at both ends are processed on two stations respectively, it is necessary to turn the workbench 180 ° after boring one hole, and then boring another hole. If the rotary axis of the worktable is eccentric e with respect to the spindle axis of the boring machine, the coaxiality error of the two holes will increase to 2E

7. How to ensure the boring accuracy of turning boring method

answer: in order to ensure the boring accuracy of the turn around boring method, the following methods can be used for workpiece alignment and clamping: that is, when clamping the workpiece, use the dial indicator to align the plane or process datum plane parallel to the boring axis, so that the alignment plane is parallel to the spindle axis of the boring machine. When the workpiece is rotated 180 ° after boring a hole, the dial indicator is still used to align the plane parallel to the spindle axis, so as to ensure the accuracy of 180 ° rotation of the workbench. After the worktable rotates, in addition to the correction plane parallel to the axis of the spindle, a dial gauge shall be installed on the boring bar to re measure whether the bored first hole is coaxial with the spindle of the boring machine. After adjustment, the second hole can be bored. If the workpiece shape is complex and there is no relevant datum or process datum, an aligned ruler or iron stopper can be installed on the worktable in advance to replace the datum on the part

8. What are the main technical requirements for parallel hole system? What methods are often used in boring to ensure the position accuracy of parallel hole system

answer: the main technical requirements of the parallel hole system are the distance accuracy and parallelism between the parallel hole axes and between the hole axis and the datum plane; Requirements for dimensional accuracy, shape accuracy and surface roughness of holes

the methods to ensure the position accuracy of the parallel hole system during boring are:

(1) in the case of single piece small batch production, the trial boring method and coordinate boring method are generally used on the horizontal boring machine or the floor boring machine

(2) medium and small-sized boxes with large batches are often processed by boring die method

9. When boring the vertical hole system, what methods can be used to ensure the position accuracy of the hole system

answer: when boring the vertical hole system, the following methods can be used to ensure the position accuracy of the hole system:

(1) use the rotary workbench boring method to use the positioning accuracy of the workbench. First, bore the hole on one end face, and then rotate the workbench 90 ° to bore the hole on the other vertical end face

(2) mandrel correction method: use the processed hole to select an inspection mandrel with the same hole diameter and insert it into the hole. After turning the workbench, use a dial indicator to calibrate both ends of the mandrel so that both ends are zero. If the workpiece structure permits, after boring the hole on the first end face, mill out the alignment base plane perpendicular to the boring machine spindle at the same time, and then turn the workbench to align the base plane so that it is parallel to the boring machine spindle

10. Detection method of parallelism of parallel hole system

answer: the parallelism detection between parallel hole systems should include the parallelism detection of the hole system axis in the vertical section and the parallelism detection of the hole system axis in the horizontal section. When detecting the parallelism of the axis in the vertical section, first insert the inspection spindle into the hole of the workpiece, and place both ends of one spindle on the equal height V-shaped frame, adjust the vertical plane composed of the axes of hole I and hole II, and make this plane perpendicular to the measuring plate, and then measure the other spindle on the given length as required. The difference between the maximum and minimum readings of the dial indicator pointer, That is, the axis parallelism error of the workpiece in the vertical direction. When detecting the parallelism error of the hole system axis in the horizontal section, it is necessary to adjust the plane containing the hole I and hole II axes to be parallel to the measuring plate, and then measure on the given length as required. The difference between the maximum and minimum readings of the dial indicator is the parallelism error of the workpiece in the horizontal direction. When the parallelism accuracy of hole system is not high, vernier caliper, micrometer or inner micrometer can also be used to directly measure the dimension between inspection spindles

11. Test method for perpendicularity of vertical hole system

answer: there are several common test methods for perpendicularity of vertical hole system:

(1) test the perpendicularity of two vertical hole axes in the same plane with an inspection mandrel with a 90 ° taper at one end. In this method, insert the inspection mandrel with a 90 ° taper at one end into the inspected hole respectively, make the conical surfaces of the two inspection mandrels contact, and then test with a feeler gauge. If the two conical surfaces do not fit, The maximum gap value will be US $1billion for the research and development of chemical materials, that is, the Perpendicularity Error of the axis of the two holes

(2) use a 90 ° angle ruler to detect the perpendicularity of the axes of two vertical holes in the same plane. This method is to insert the inspection mandrel into one hole with the cooperation of the guide sleeve, extend the boring bar into the other hole that has been machined, fit the 90 ° angle ruler with the inspection mandrel and the boring bar, and then use a feeler ruler to detect the contact surface gap of the 90 ° angle ruler. The maximum gap measured is the Perpendicularity Error of the axes of the two holes

(3) check the perpendicularity of the axes of two vertical holes that are not in the same plane with the inspection mandrel and dial indicator. When using this method, insert the inspection mandrel into one hole with the cooperation of the guide sleeve, extend the boring bar into another machined hole to be measured, and install a dial indicator on the boring bar. During measurement, manually rotate the spindle and drive the dial indicator to measure the reading values of the two measuring points of the spindle. The difference between the maximum and minimum readings is the Perpendicularity Error of the two hole axes

12. Main technical measures for boring large holes and long holes

answer: when boring large holes and long holes with overhang boring method, in order to reduce the overhang length of the spindle, the boring tool rack can be directly installed on the spindle, and the spindle rack or spindle support sleeve can be attached to increase the rigidity of the boring bar. When boring large and long holes with the tailstock of the boring machine, first of all, the coaxiality of the tailstock support and the spindle hole of the boring machine should be accurately adjusted, and then the follow-up support device should be used to reduce the vibration of the cutter bar in the boring of large and long holes. When boring holes with an aperture greater than 800mm and a length greater than 2000mm, the differential boring bar can be used for boring. In addition, the geometric parameters and cutting parameters of the tool must be reasonably selected, and the appropriate cutting fluid must be filled to fully cool and lubricate

13. What is the boring principle? How to execute correctly

answer: the so-called boring principle refers to the comprehensive judgment of boring elements such as specific processing objects (workpiece material, shape and structure), processing properties (rough boring, semi precision boring and precision boring)

during rough boring, the machining allowance is relatively large. At this time, the production efficiency should be considered first, and then the machining accuracy. Therefore, firstly, the cutting depth should be increased to reduce the feeding times; 3. Regularly check the screw at the jaw to increase the feed rate; Finally, the cutting speed corresponding to the cutting depth and feed rate is selected

during fine boring, it is mainly to ensure the accuracy of the hole and the surface roughness requirements of the hole. In order to ensure the surface roughness and improve the production efficiency, the cutting speed should be increased; The feed rate should not be too large. Because the machining allowance of fine boring is often small, the cutting depth is limited by the allowance and cannot be selected arbitrarily

14. Taking the spindle box of boring lathe as an example, the advantages and disadvantages of selecting one side and two pin holes as positioning precision datum are analyzed

answer: when the production batch is large, boring box parts often takes one side and two pin holes as the positioning precision benchmark. The utility model has the advantages that the structure of the fixture is simplified, the rigidity of the fixture is improved, and the workpiece loading and unloading is convenient, so the labor productivity and the processing quality can be improved. The disadvantage is that the positioning datum and design datum do not coincide

Copyright © 2011 JIN SHI