High-precision variable-section slender rod part machining device and machining method
阅读说明：本技术 一种高精度变截面长细杆零件加工装置及加工方法 (High-precision variable-section slender rod part machining device and machining method ) 是由 贾小强 王俊 向阳 王辉 祖宁军 于 2020-08-18 设计创作，主要内容包括：本发明公开了一种高精度变截面长细杆零件加工装置及加工方法,本加工装置包括分度盘、主轴、尾顶尖、卡盘、工作台,所述工作台的一端设置有尾顶尖,对应另一端设置有分度盘,该分度盘对应尾顶尖的这侧设置有卡盘,另一端设置有驱动卡盘转动的分度伺服电机,其特征在于,所述工作台上还设置有与数控铣床连接的主轴,该主轴上设置有砂轮；通过该装置将铣刀铣削进刀量、横向移动的设置变更为砂磨圆弧角和二次拟合曲线等参数的设定,本发明采用弦切砂轮磨削技术加工长细杆零件,降低长细杆零件的加工难度,提高了加工效率及合格率。(The invention discloses a high-precision variable-section slender rod part machining device and a machining method, wherein the machining device comprises an index plate, a main shaft, a tail center, a chuck and a workbench, wherein the tail center is arranged at one end of the workbench, the index plate is arranged at the other end of the workbench correspondingly, the chuck is arranged at the side of the index plate corresponding to the tail center, and an index servo motor for driving the chuck to rotate is arranged at the other end of the index plate; the device changes the milling feed amount and the transverse movement setting of the milling cutter into the setting of parameters such as a sanding arc angle, a quadratic fit curve and the like.)
1. The utility model provides a high accuracy variable cross section slender rod parts machining device, includes graduated disk, main shaft, tail top, chuck, workstation, the one end of workstation is provided with the tail top, corresponds the other end and is provided with the graduated disk, and this side that this graduated disk corresponds the tail top is provided with the chuck, and the other end is provided with drive chuck pivoted graduation servo motor, its characterized in that, still be provided with the main shaft of being connected with numerically controlled fraise machine on the workstation, be provided with the emery wheel on this main shaft.
2. A high precision variable cross section slender rod parts processing device according to claim 1, wherein said main shaft is provided with a grinding wheel rod, on which a grinding wheel is mounted, and the grinding wheel is fixed to the grinding wheel rod by means of a washer and a nut.
3. A method for processing a long and thin rod part with a variable cross-section at high accuracy by using the processing apparatus according to claim 1 or 2, comprising the steps of:
s1, selecting a workpiece, calculating the radial grinding amount through the actual size and the pattern of the workpiece by the formula (1), and calculating the arc surface angle through the formula (2):
Δx＝x0-x (1)
in the formulae (1) and (2), x0The radius of the cross section of the workpiece before grinding, the radius of the cross section of the workpiece after grinding, and theta is an indexing rotation angle selected by moving and grinding the workpiece in the Y direction A direction each time;
and (3) fitting to approach variable speed motion by adopting a segmented quadratic fit curve according to the length and the shape of the workpiece, wherein the number of segments is not less than that of pattern segments, and each segment of shape definition should satisfy quadratic function formula (3):
YN＝a0+a1·x+a2·x2(y∈ΔYNΔYN＝YN-YN-1N＝1，2，…) (3)
in formula (3): a is0，a1，a2Respectively an initial value and a weighting factor, a0，a1，a2Must be obtained before the parameters are injected into the numerical control milling machine, a0，a1，a2According to the workpiece radius, length value and intermediate interpolation corresponding to each section of curve end point of the workpiece: (x)n，yn)、(xn+1，yn+1) And (x)nc，ync) And substituting the solution into the solution (3) to obtain:
a0＝yN-a1xN-a2xN 2(4)
order toThen
a1＝-k1n*k4n+k3n*k5n(7)
a1＝k2n*(k1n-k3n) (8)
To take values conveniently, let
ync＝(yn+yn+1)/2 (9)
Then according to the corresponding y in the patternncMeasure xnc；
Once the workpiece is selected, corresponding processing parameters and functions are obtained according to the formulas (1) to (9); programming and writing the processing parameters and functions of the workpiece into a control console of the numerical control milling machine or the numerical control processing center;
and S2, fixing the workpiece on a numerical control milling machine, mounting the workpiece on a chuck, clamping and fixing the workpiece by using a tail center, pressing a start button, and grinding the workpiece by using a chordal cutting grinding wheel by using the milling machine according to an injection program.
4. The method for machining the high-precision long and thin rod part with the variable cross section according to claim 3, wherein the chord cutting grinding wheel is used for grinding at least chord cutting for 2 times, the workpiece is rotated through an indexing servo motor, and an appropriate chord grinding and milling angle is selected and adjusted continuously.
5. The method for processing the high-precision slender rod part with the variable cross section according to claim 3, wherein the quadratic fitting curve fitting approximation is that in the processing of the selected high-precision slender rod part with the variable circular cross section, the workpiece is subjected to numerical control grinding processing according to a similar or approximate part demand curve or a theoretical curve on the premise of a given grinding amount and a given dividing angle each time the workpiece moves axially.
6. A method for manufacturing a high-precision slender rod with variable cross-section according to claim 3, wherein after said step S2, a belt-cutting and grinding process is used.
7. A method for processing a long and thin rod with a high precision and a variable cross section according to claim 3, wherein when the machining allowance of the workpiece blank is large, the steps of turning, heat treatment and grinding are adopted before the processing step S2.
Technical Field
The invention relates to the technical field of part machining, in particular to a high-precision variable-section slender rod part machining device and method.
Background
The lathe is an important means for machining and is widely applied to the part machining and manufacturing industries; the circular rod-shaped part is usually machined by a lathe turning method, but for the circular rod-shaped part with a high-precision long and thin rod (L/d is more than 20), the precision of the part is difficult to meet by the lathe turning method, even if the circular rod-shaped part is machined by limited force, the yield is reduced sharply along with the reduction of the rod diameter of the part, and the rejection rate is increased greatly.
In important application fields such as atomic energy reactors, the demand of high-precision variable-circular-section slender rod parts is large; for the processing of high-precision variable-cone-section slender rod parts, especially slender rod parts with the length of more than 400mm and the diameter of 4mm-5mm, the lathe cutting which is always strong for processing cylindrical parts has been diligent.
The lathe processing method is that a part is fixed on the clamps at the two ends and is driven to rotate by the servo motor, and meanwhile, the screw drives the turning tool to move in the horizontal direction to cut a workpiece, as shown in fig. 5; lathe processing of slender rod parts has two major problems: firstly, in the processing process, a swinging phenomenon (radial swinging, same as below) occurs in the middle of a part in high-speed rotation, and the swinging phenomenon can cause the contact point of a turning lathe to jump; secondly, in the cutting process of the turning tool, the turning tool contacts the part to generate radial jacking force, and when the middle part of the part is turned, the part can generate larger elastic deformation to influence the cutting feed amount; the occurrence of the two conditions naturally affects the processing quality and the processing precision; the cause of the problem is: the part features are determined, the part is small in diameter, long in length and easy to elastically deform; secondly, the lathe processing mode is determined, before turning processing, a part is clamped and fixed by a lathe center, the lathe is started again, the part rotates at a high speed along with the part, the lathe tool cuts according to an instruction, tiny elastic deformation can be generated in the jacking process of the slender rod-shaped part, the two ends of the part are fixed, the middle of the part is suspended, when the part rotates at a high speed along with the lathe, a certain rotary swing deviating from the axial direction is inevitably generated in the middle part, the swing directly influences the contact and the feed amount of the lathe tool and the part, if the swing amplitude of the cutting point is too large, the contact between the lathe tool and the part is similar to or not, even the contact is impossible, even if the contact is generated, the rotary swing of the part is increased, and the jumping or discontinuous cutting of the cutting point of the lathe tool is caused; further, if a non-uniform circular variable cross-section workpiece is machined, the lathe bed cannot be used.
The invention aims to create a part processing way and a method on the premise of ensuring the part precision and the processing qualification rate, and avoid two problems of turning long and thin rod parts.
Disclosure of Invention
The invention aims to: the high-precision slender rod variable cross-section part can be processed with high quality by a grinding processing method of radial chord cutting and axial quadratic curve piecewise approximation, and is very suitable for processing the high-precision slender rod variable cross-section part by practice application, and the processing precision can reach 3 per thousand.
The technical scheme adopted by the invention is as follows: the utility model provides a high accuracy variable cross section slender rod parts machining device, includes graduated disk, main shaft, tail top, chuck, workstation, the one end of workstation is provided with the tail top, corresponds the other end and is provided with the graduated disk, and this side that this graduated disk corresponds the tail top is provided with the chuck, and the other end is provided with drive chuck pivoted graduation servo motor, its characterized in that, still be provided with the main shaft of being connected with numerically controlled fraise machine on the workstation, be provided with the emery wheel on this main shaft.
The working principle of the invention is as follows: modification of hardware: replacing a milling cutter on the original milling machine with a grinding wheel, fixing the grinding wheel to the front end of the milling cutter, and changing milling of the milling cutter into grinding of the grinding wheel; setting a sanding arc angle, namely changing the milling feed amount and the transverse movement setting of the milling cutter into the setting of parameters such as the sanding arc angle and a quadratic fit curve, and changing the milling grinding technology into turning and milling into grinding; selecting a 4-axis numerical control milling machine as processing equipment, as shown in figure 1, replacing a milling cutter at the front end of a main shaft with a grinding wheel, and respectively injecting Y-direction (axial direction), X-direction (radial direction) and A-direction (circumferential direction) parameters of a workpiece through a numerical control operation table to automatically complete the processing of the high-precision slender rod variable-section part.
Optionally, a grinding wheel rod is arranged on the main shaft, a grinding wheel is mounted on the grinding wheel rod, the grinding wheel is fixed on the grinding wheel rod through a gasket and a nut, and the grinding wheel is detachably mounted and is convenient to replace.
The invention discloses a high-precision variable-section slender rod part machining method, which uses a machining device provided by the invention and is characterized by comprising the following steps of:
s1, selecting a workpiece, calculating the radial grinding amount through the actual size and the pattern of the workpiece by the formula (1), and calculating the arc surface angle through the formula (2):
Δx＝x0-x (1)
in the formulae (1) and (2), x0The radius of the cross section of the workpiece before grinding, the radius of the cross section of the workpiece after grinding, and theta is an indexing rotation angle selected by moving and grinding the workpiece in the Y direction A direction each time;
and (3) fitting to approach variable speed motion by adopting a segmented quadratic fit curve according to the length and the shape of the workpiece, wherein the number of segments is not less than that of pattern segments, and each segment of shape definition should satisfy quadratic function formula (3):
YN＝a0+a1·x+a2·x2(y∈ΔYNΔYN＝YN-YN-1N＝1，2，…) (3)
in formula (3): a is0，a1，a2Respectively an initial value and a weighting factor, a0，a1，a2Must be obtained before the parameters are injected into the numerical control milling machine, a0，a1，a2The calculation can be carried out according to the workpiece radius, the length value and the intermediate interpolation corresponding to each section of curve end point of the workpiece: (x)n，yn)、(xn+1，yn+1) And (x)nc，ync) And substituting the solution into the solution (3) to obtain:
a0＝yN-a1xN-a2xN 2(4)
order toThen
a1＝-k1n*k4n+k3n*k5n(7)
a1＝k2n*(k1n-k3n) (8)
To take values conveniently, let
ync＝(yn+yn+1)/2 (9)
Then according to the corresponding y in the patternncMeasure xnc；
Once the workpiece is selected, corresponding processing parameters and functions are obtained according to the formulas (1) to (9); programming and writing the processing parameters and functions of the workpiece into a control console of the numerical control milling machine or the numerical control processing center;
and S2, fixing the workpiece on a numerical control milling machine, mounting the workpiece on a chuck, clamping and fixing the workpiece by using a tail center, pressing a start button, and grinding the workpiece by using a chordal cutting grinding wheel by using the milling machine according to an injection program.
Optionally, the string cutting grinding wheel grinds the string for at least 2 times, and rotates the workpiece through the indexing servo motor, and the proper string grinding and milling angle is selected and adjusted continuously.
Optionally, the fitting approximation of the quadratic fit curve is that in the processing of the selected high-precision slender rod variable-circle section part, on the premise of a given grinding amount and a given dividing angle, the workpiece is subjected to numerical control grinding processing according to a similar or close part demand curve or a theoretical curve each time the workpiece moves axially.
Optionally, after the processing step S2, a sand belt cutting and grinding process is adopted.
Optionally, when the machining allowance of the workpiece blank is large, before the machining step S2, turning, heat treatment and grinding are performed.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
the milling cutter of the existing numerical control milling machine is modified, the grinding wheel is fixed at the front end of the milling cutter, the milling of the milling cutter is changed into grinding of the grinding wheel, the processing precision is more guaranteed, and the modification cost is low;
the milling cutter is changed into the settings of parameters such as a sanding arc angle, a quadratic fit curve and the like according to the settings of milling feed amount and transverse movement of the milling cutter; the grinding and milling technology is changed into turning and milling into grinding, milling and milling machining points and directions can be flexibly selected according to installation limitation and a moving mode of a milling head clamp of a milling machine, the grinding points can be selected from one of the upper side, the lower side and the front side, the machining directions can be sequentially moved from left to right (or from right to left), the numerical control milling machine is suitable for a general milling machine and a numerical control milling machine, the machining efficiency is higher by adopting four-axis or more than four-axis numerical control milling machines, and the machining precision is more guaranteed.
On the basis of not changing the working principle and the processing mode of the milling machine, the invention not only overcomes the defect of the flexible swing caused by the rotation of the workpiece processed by the lathe, but also avoids the problems that the conventional numerical control machine with high hardness and small allowance cannot process or the precision is difficult to ensure.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of a 4-axis numerically controlled milling machine for machining a long and thin rod part by chordal cutting, milling and grinding;
FIG. 2 is a schematic view of a radial machining cross-section of a workpiece;
FIG. 3 is a schematic axial outer surface curve of a workpiece;
FIG. 4 is a schematic view of the chordal grinding of the wheel;
FIG. 5 is a schematic view of a prior art lathe process;
labeled as: 1-an index plate, 2-a main shaft, 3-a tail center, 4-a workpiece, 5-a chuck, 6-a workbench, 7-a grinding wheel rod, 8-a grinding wheel, 9-a gasket, 10-a nut and 11-an index servo motor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1-4, a high-precision variable-section slender rod part processing device comprises an index plate 1, a
The working principle of the invention is as follows: modification of hardware: replacing a milling cutter on the original milling machine with a
The
The invention discloses a high-precision variable-section slender rod part machining method, which uses a machining device provided by the invention and is characterized by comprising the following steps of:
s1, selecting a workpiece, calculating the radial grinding amount through the actual size and the pattern of the workpiece by the formula (1), and calculating the arc surface angle through the formula (2):
Δx＝x0-x (1)
in the formulae (1) and (2), x0The radius of the cross section of the workpiece before grinding, the radius of the cross section of the workpiece after grinding, and theta is an indexing rotation angle selected by moving and grinding the workpiece in the Y direction A direction each time;
and (3) fitting to approach variable speed motion by adopting a segmented quadratic fit curve according to the length and the shape of the workpiece, wherein the number of segments is not less than that of pattern segments, and each segment of shape definition should satisfy quadratic function formula (3):
YN＝a0+a1·x+a2·x2(y∈ΔYNΔYN＝YN-YN-1N＝1，2，…) (3)
in formula (3): a is0，a1，a2Respectively an initial value and a weighting factor, a0，a1，a2Must be injected into the numerical control milling machine in parametersA is obtained by0，a1，a2The calculation can be carried out according to the workpiece radius, the length value and the intermediate interpolation corresponding to each section of curve end point of the workpiece: (x)n，yn)、(xn+1，yn+1) And (x)nc，ync) And substituting the solution into the solution (3) to obtain:
a0＝yN-a1xN-a2xN 2(4)
order toThen
a1＝-k1n*k4n+k3n*k5n(7)
a1＝k2n*(k1n-k3n) (8)
To take values conveniently, let
ync＝(yn+yn+1)/2 (9)
Then according to the corresponding y in the patternncMeasure xnc；
Once the workpiece is selected, corresponding processing parameters and functions are obtained according to the formulas (1) to (9); programming and writing the processing parameters and functions of the workpiece into a control console of the numerical control milling machine or the numerical control processing center;
and S2, fixing the workpiece on a numerical control milling machine, mounting the workpiece on a chuck, clamping and fixing the workpiece by using a tail center, pressing a start button, and grinding the workpiece by using a chordal cutting grinding wheel by using the milling machine according to an injection program.
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