CN115229253A - Split type damping vibration attenuation milling cutter for valve body machining - Google Patents
Split type damping vibration attenuation milling cutter for valve body machining Download PDFInfo
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- CN115229253A CN115229253A CN202210990862.8A CN202210990862A CN115229253A CN 115229253 A CN115229253 A CN 115229253A CN 202210990862 A CN202210990862 A CN 202210990862A CN 115229253 A CN115229253 A CN 115229253A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23C—MILLING
- B23C5/00—Milling-cutters
- B23C5/003—Milling-cutters with vibration suppressing means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23C—MILLING
- B23C5/00—Milling-cutters
- B23C5/02—Milling-cutters characterised by the shape of the cutter
- B23C5/10—Shank-type cutters, i.e. with an integral shaft
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Abstract
The invention discloses a split type damping vibration attenuation milling cutter for machining a valve body, which comprises a cutter head, a cutter bar, a damping gasket and a connecting piece, wherein the cutter bar is arranged on the cutter head; the cutter head is provided with a cutter head cavity, and the tail part of the cutter head is provided with a cutter head connecting tooth; the head of the cutter bar is provided with a cutter bar connecting tooth, and the axis position is provided with a threaded inner hole; the tail part of the cutter head is in inserted fit with the head part of the cutter bar; gaps are reserved on the side surfaces of the adjacent cutter head connecting teeth and the cutter bar connecting teeth after the cutting-in connection so as to place damping gaskets; the connecting piece comprises self-locking screw and packing ring, and self-locking screw passes packing ring and tool bit cavity, and the axial pretightning force with certain size of cutter arbor screw thread hole at cutter arbor head connects the locking. Through setting up the size of axial pretightning force, make split type damping vibration attenuation milling cutter when valve body mills the in-process and surpass specific moment of torsion, tool bit and cutter arbor produce relative rotation, compress the damping gasket, restrain the impact vibration of cutter, reduce the risk that the blade bursts at the edge, disturb the frequency of milling power simultaneously, restrain the emergence of cutting chatter, improve processingquality.
Description
Technical Field
The invention belongs to the technical field of milling cutters, and particularly relates to a split type damping vibration attenuation milling cutter for valve body machining.
Background
Valve body parts generally involve milling of structural features such as holes, grooves, cavities, etc., during which the milling cutter is subjected to alternating loads at the nose portion which force the milling cutter to vibrate. Because milling cutter hangs deeply great, the quiet rigidity of cutter body itself is low, and the amplitude increase of tool bit causes the machined surface to be not conform to the part surface roughness requirement. And when the frequency of the alternating load is close to the natural frequency of the milling cutter, the cutting chatter phenomenon is generated, which greatly increases the vibration amplitude of the milling cutter, influences the processing precision and reduces the service life of the machine tool and the cutter. Meanwhile, alternating load of the tool bit part causes great impact on the blade, so that sudden damage such as tipping, damage and the like occurs to the blade, and the blade is replaced after shutdown even the surface of a workpiece is damaged. Therefore, how to reduce the vibration of the milling cutter in the machining process is a key and difficult problem of ensuring the machining quality in the metal milling process.
The prior art measures for damping vibration in the machining process of the milling cutter and the limitations thereof are as follows:
1. inlaid hard alloy material
Vibration reduction measures are as follows: the static rigidity is improved by embedding hard alloy materials with high rigidity and strength in parallel at two sides of the cutter bar.
Limitation: the length to diameter ratio of such a shank is limited by the stiffness and thickness of the two reinforcing materials and the tightness of their adhesion to the tool body, and is generally suitable for machining applications with relatively low milling forces.
2. Reducing the weight of the tool bit portion
Vibration reduction measures are as follows: the weight of the bit part is reduced with a very small influence on the static stiffness.
Limitation: the application of the head-cutting method has its own limitations and the aspect ratio cannot be made large.
3. Optimizing tool tip cutting edge geometry
Vibration reduction measures are as follows: the cutting edge of the cutter head adopts special geometric shapes such as a variable helix angle, a variable tooth pitch angle and the like, the frequency of milling force is disturbed, and the occurrence of cutting chatter is restrained.
Limitation: the sharpening method of the cutting edge with special geometric shapes such as variable helix angle, variable tooth pitch angle and the like is complex, the precision detection difficulty of the cutting edge is very high, the sharpening difficulty of the worn cutter is very high, and the cost of the cutter is high.
4. The interior of the cutter bar is provided with a vibration damping block
Vibration reduction measures are as follows: a cavity is obtained by removing part of the material at the front end of the cutter rod, and an elastic body and a mass block are additionally arranged in the cavity to form the impact damping device.
Limitation: the volume of the damping mass is limited by the size of the shank and the life of such a tool is severely limited by the life of the damper.
5. Vibration damping particles are added in the cutter bar
Vibration reduction measures are as follows: a part of the front end of the cutter rod is removed to obtain a cavity, particulate matters are added into the cavity, and the collision and friction among particles are utilized to dissipate vibration energy.
Limitation: the damping effect of the damping is related to the size of the cavity, the filling ratio, the particle type and other factors. But there is no perfect theoretical model for particle damping characteristics; the contact force of the particles in motion cannot be measured, and only an approximate value can be indirectly obtained through simulation, so that a good vibration reduction effect cannot be accurately obtained.
In addition, when the structural features of the valve body are machined, the plurality of blades circumferentially arranged at the tail of the cutter head cut into a workpiece along with the turnover of the cutter head, and materials are removed. In the process, the workpiece applies periodic milling force to the blades, namely for any blade, the milling cutter rotates for one circle, the blade cuts into and cuts out the workpiece once, and the workpiece is impacted by the periodic milling force. In the high-speed turnover of the milling cutter, the blade is subjected to periodic impact, wherein impact load in the tangential direction, namely tangential milling force, is a main cause of damage and tipping of the cutter. The milling cutter vibration reduction methods in the prior art do not accurately and actively reduce the impact load in the cutter machining process, and have certain limitation on the protection of the cutter.
Disclosure of Invention
The invention aims to solve or improve the problems by providing a split damping milling cutter for machining a valve body, aiming at overcoming the defects in the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that:
the utility model provides a split type damping vibration attenuation milling cutter for valve body processing which characterized in that includes: the cutter comprises a cutter head, a cutter rod, a cutter blade and a connecting piece; the cutter head and the cutter bar are both in a cylindrical structure, the sections of the cutter head and the cutter bar are both circular sections, and the cutter head and the cutter bar are coaxially arranged; the tail part of the cutter head is connected with the head part of the cutter bar, and the plurality of blades are circumferentially arranged at the head part of the cutter head;
the cutter head is provided with a cutter head cavity, the cutter head cavity penetrates through the cutter head along the axis direction of the cutter head, the tail of the cutter head is provided with cutter head connecting teeth, a plurality of cutter head connecting teeth are circumferentially distributed at intervals along the circular section of the tail of the cutter head, and the adjacent two sides of any one cutter head connecting tooth are provided with cutter head connecting grooves;
a cutter bar threaded inner hole is formed in the axis position of the cutter bar, the cutter bar threaded inner hole extends from the head of the cutter bar to the tail of the cutter bar along the axis of the cutter bar, the cutter bar threaded inner hole is a blind hole, cutter bar connecting teeth are arranged at the head of the cutter bar, a plurality of cutter bar connecting teeth are circumferentially distributed at intervals along the circular cross section of the head of the cutter bar, and a cutter bar connecting groove is formed in each two adjacent sides of any one of the cutter bar connecting teeth;
the tail part of the cutter head is in inserting fit with the head part of the cutter rod, the cutter head connecting tooth is inserted in the cutter rod connecting groove, and the cutter rod connecting tooth is inserted in the cutter rod connecting groove; after the cutting-in, the two sides of any cutter bar connecting tooth are cutter bar connecting teeth, and the two sides of any cutter bar connecting tooth are cutter bar connecting teeth; after the insertion, gaps are reserved on the side surfaces of the adjacent cutter head connecting teeth and the cutter bar connecting teeth, and damping gaskets are placed in the gaps; the cutter head connecting teeth and the cutter bar connecting grooves are connected and matched with each other to form a plurality of axial end faces at the connecting and matching positions of the cutter head connecting grooves and the cutter bar connecting teeth;
the connecting piece comprises a self-locking screw and a gasket, and the self-locking screw penetrates through the gasket, the cutter head cavity and the cutter bar thread inner hole at the head part of the cutter bar;
axial pretightening force is applied to the self-locking screw, and the annular axial end face at the joint and matching position of the cutter head and the cutter bar generates static friction force under the action of the axial pretightening force; and determining the axial pretightening force for fastening the self-locking screw according to the tangential milling force in the machining process, so that when the torque generated by the tangential milling force exceeds the friction torque generated by the axial pretightening force, the cutter head and the cutter bar rotate relatively, and the adjacent cutter head connecting teeth and the cutter bar connecting teeth extrude the damping gasket in the gap.
In order to ensure that the damping gasket performs compression damping near the tangential milling force peak value and reduce the tangential milling force peak value, the determination method of the axial pretightening force F is as follows. The axial end face of the joint of the cutter head connecting tooth and the cutter bar connecting tooth generates static friction force under the action of axial pretightening force, and controls the maximum torque M which can be generated by the static friction force f The maximum value M of the torque generated by the tangential milling force in the milling process is achieved F_max When the time is 0.8 times, the cutter head connecting teeth and the cutter bar connecting teeth rotate relatively, and the damping gasket is compressed for damping, namely M f And M F_max The equation needs to be satisfied: m is a group of f =0.8M F_max 。
Maximum torque M generated by tangential milling force in milling F_max The calculation formula of (2) is as follows: m is a group of F_max =F t_max R, wherein F t_max The maximum value of the tangential milling force in milling processing is shown, and R is the excircle radius of the circular section of the cutter head.
The cutter head connecting teeth and the cutter bar connecting grooves are connected and matched with a plurality of axial end faces at the connecting and matching positions, and the cutter head connecting grooves and the cutter bar connecting teeth are connected and matched with a plurality of axial end faces at the connecting and matching positions to jointly form a circular annular axial end face. The tool bit is characterized in that a circular ring-shaped axial end face generates static friction force under the action of axial pretightening force, the inner diameter of the circular ring-shaped axial end face is the excircle radius R' of the circular section of the tool bit, the outer diameter of the circular ring-shaped axial end face is the excircle radius R of the circular section of the tool bit, and the maximum torque M which can be generated by the static friction force f The calculation formula of (2) is as follows:
wherein R' is the radius of the inner circle of the circular section of the cutter head, dM is the friction torque borne by a circular ring surface infinitesimal with the inner circle radius R and the width dr in the circular axial end surface, and dr is close to infinity; the formula of the friction force and the torque borne by the circular ring surface infinitesimal element is as follows: dM = r μ dF, where μ is the coefficient of friction and dF is the positive pressure to which the toroid element is subjected; the positive pressure on the micro-elements of the torus is represented by the following formula: dF = PdS, wherein P is the pressure applied to the torus, and dS is the infinitesimal area; micro element area meterThe formula is as follows: dS = pi (r + dr) 2 －πr 2 =2πrdr+π(dr) 2 =2 π rdr; the pressure intensity of the circular ring surface is represented by the following formula: p = F/π (R) 2 −R' 2 ) Wherein F is the axial pretightening force, R is the excircle radius of the section of the circular ring of the cutter head, and R' is the inner circle radius of the section of the circular ring of the cutter head; can be calculated to obtain
M obtained by f Substituting into the above M f And M F_max The equation needs to be satisfied: m f =0.8M F_max =0.8F t_max R, the value of the axial pretightening force F is as follows: f =1.2F t_max R(R 2 −R' 2 )/μ(R 3 −R' 3 )。
Preferably, the maximum value of the tangential milling force in the milling process is calculated by the cutting force theory.
Preferably, the maximum value of the tangential milling force in the milling process is obtained by historical milling force monitoring data in the past process.
Preferably, the height of the cutting head is as small as possible without interfering with the cutting process to increase the stiffness of the tool.
Preferably, the diameter of the cavity of the cutter head is 1mm to 2mm larger than that of the self-locking screw.
Preferably, the damping gasket material is damping alloy or rubber.
Preferably, the cutter head and the cutter bar are made of tool steel or hard alloy, and the self-locking screw and the gasket are made of carbon steel or stainless steel.
The split type damping vibration attenuation milling cutter for machining the valve body has the following beneficial effects:
1. the pretightening force of the cutter head and the cutter bar connecting piece is set according to the tangential milling force, so that a damping gasket between the cutter head and the cutter bar of the split damping vibration attenuation milling cutter compresses damping near the peak value of the tangential milling force, the peak value of the tangential milling force is accurately and reliably reduced, the blade cutting impact load in the cutter machining process is reduced, the machining quality is ensured, and the service life of the cutter is prolonged.
2. According to the invention, the pretightening force is accurately calculated according to the magnitude of the cutting force, so that the damping gasket is only pressed when the torque exceeds the limit, the service life of the damping gasket is prolonged while the vibration reduction effect of the cutter is ensured, the cutter installation accuracy error caused by frequently dismounting and replacing the gasket is reduced, the processing efficiency is improved, and the cost is saved.
3. Because the tool bit and the tool bar rotate relatively to compress the damping gasket, the dynamic process of cutting the blade into and out of a workpiece is changed, the frequency of milling force can be disturbed, and the cutting chatter is inhibited.
4. The connection mode of the toothed cutter head and the cutter bar improves the torsion resistance and the shear resistance of the joint and has high connection stability.
Drawings
Fig. 1 is a schematic structural view of a split type damping vibration attenuation milling cutter for valve body machining provided by the invention.
FIG. 2 is a schematic view of a circular section and a circular infinitesimal view of a tool tip.
Fig. 3 is a schematic diagram of the variation of tangential milling force with the rotation angle of the tool in milling with a non-vibration damping milling cutter.
Fig. 4 is a schematic diagram of the change of the tangential milling force along with the rotation angle of the cutter in milling process by adopting a split type damping vibration attenuation milling cutter.
The mark in the figure is: 1-cutter head, 2-cutter bar, 3-damping gasket, 4-connecting piece, 5-cutter head cavity, 6-cutter head connecting tooth, 7-cutter bar connecting tooth, 8-cutter bar threaded inner hole, 9-self-locking screw, 10-gasket, 11-cutter blade and 12-circular annular axial end face.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
A split damping and vibration damping milling cutter for valve body machining, as shown in fig. 1, comprising: the cutter head 1, the cutter bar 2, the blade 11 and the connecting piece 4. Tool bit 1 and cutter arbor 2 are the cylinder structure, and tool bit 1 is the ring cross-section with the 2 cross-sections of cutter arbor, and tool bit 1 sets up with cutter arbor 2 is coaxial. The tail of the cutter head 1 is connected with the head of the cutter bar, and the plurality of blades 11 are circumferentially arranged at the head of the cutter head.
The tool bit 1 is provided with a tool bit cavity 5, the tool bit cavity 5 penetrates in the tool bit 1 along the axis direction of the tool bit, the tail of the tool bit 1 is provided with tool bit connecting teeth 6, the tool bit connecting teeth 6 are distributed along the circumferential interval of the circular section at the tail of the tool bit 1, and the tool bit connecting grooves are formed in the two adjacent sides of any tool bit connecting teeth 6.
The axis position of the cutter rod 2 is provided with a cutter rod thread inner hole 8, the cutter rod thread inner hole 8 extends from the head of the cutter rod 2 to the tail of the cutter rod along the axis of the cutter rod, the cutter rod thread inner hole 8 is a blind hole, the head of the cutter rod 2 is provided with a cutter rod connecting tooth 7, the cutter rod connecting teeth 7 are circumferentially distributed at intervals along the circular section of the head of the cutter rod 2, and two adjacent sides of any one cutter rod connecting tooth 7 are cutter rod connecting grooves.
The tail of the cutter head 1 is in plug-in fit with the head of the cutter rod 2, the cutter head connecting tooth 6 is in plug-in connection with the cutter rod connecting groove, and the cutter rod connecting tooth is in plug-in connection with the cutter head connecting groove. After the insertion, the two sides of any cutter bar connecting tooth 6 are cutter bar connecting teeth 7, and the two sides of any cutter bar connecting tooth 7 are cutter bar connecting teeth 6. After the insertion, gaps are reserved between the adjacent cutter head connecting teeth 6 and the cutter bar connecting teeth 7, and damping gaskets 3 are placed in the gaps. The cutter head connecting teeth and the cutter bar connecting grooves are connected and matched with a plurality of axial end faces at the connecting and matching positions, and the cutter head connecting grooves and the cutter bar connecting teeth are connected and matched with a plurality of axial end faces at the connecting and matching positions to jointly form a circular annular axial end face 12.
The connecting piece 4 comprises a self-locking screw 9 and a gasket 10, wherein the self-locking screw 9 penetrates through the gasket 10 and the cutter head cavity 5 and is connected with a cutter bar threaded inner hole 8 at the head part of the cutter bar. Axial pretightening force is applied to the self-locking screw 9, and the annular axial end face 12 at the joint and matching position of the cutter head and the cutter bar generates static friction force under the action of the axial pretightening force. The axial pretightening force for fastening the self-locking screw is determined according to the tangential milling force in the machining process, so that when the torque generated by the tangential milling force exceeds the maximum static friction torque generated by the axial pretightening force, the cutter head 1 and the cutter bar 2 rotate relatively, and the adjacent cutter head connecting teeth 6 and the adjacent cutter bar connecting teeth 7 extrude the damping gaskets 3 in the gap, so that the impact vibration of the milling cutter is inhibited, the risk of tipping of the cutter blade 11 is reduced, the frequency of the milling force is disturbed, and the cutting chatter is avoided.
The working principle is as follows: when the milling cutter rotates for milling, the blade 11 on the periphery of the head of the cutter head 1 cuts into a workpiece and is subjected to milling force applied to the workpiece, wherein the tangential milling force generates torque, so that the cutter head 1 and the cutter bar 2 have a tendency to rotate relatively. The axial pretightening force provided by the self-locking screw 9 enables the circular ring-shaped axial end face at the joint matching part of the cutter head 1 and the cutter bar 2 to generate static friction torque for preventing relative rotation. When the torque generated by the tangential milling force is normally increased and exceeds the maximum static friction torque, the cutter head 1 and the cutter rod 2 generate instantaneous tiny relative rotation, the cutter rod connecting teeth and the cutter head connecting grooves generate instantaneous tiny relative rotation, and the adjacent cutter head connecting teeth 6 and the cutter rod connecting teeth 7 extrude the damping gasket 3 in the gap to damp and reduce the impact force.
In order to accurately and reliably reduce the peak value of the tangential milling force and ensure that the damping gasket can effectively perform compression damping near the peak value of the tangential milling force, the determination method of the axial pretightening force F comprises the following step of controlling the maximum torque M which can be generated by the static friction force of the tool bit 1 and the tool bar 2 under the action of the axial pretightening force f The maximum value M of the torque generated by the tangential milling force in the milling process is achieved F_max 0.8 times, the cutter head connecting tooth and the cutter bar connecting tooth generate relative rotation, namely M f And M F_max The formula one needs to be satisfied: m f =0.8M F_max 。
As shown in fig. 2, the outer circle radius of the circular section of the tool bit is R, the inner circle radius of the circular section of the tool bit is R', the infinitesimal inner circle radius of the circular ring surface of the circular section of the tool bit is R, and the width is dr.
Maximum torque M generated by tangential milling force in milling F_max The calculation formula of (2) is formula two: m F_max =F t_max R, wherein F t_max The maximum value of the tangential milling force in milling processing is shown, and R is the excircle radius of the circular section of the cutter head.
Maximum torque M generated by static friction force of tool bit and tool bar under action of axial pretightening force f The calculation formula of (2) is formula three:
wherein R' is the radius of the inner circle of the section of the circular ring of the tool bit, and dM is the friction torque borne by the infinitesimal of the circular ring surface with the radius R and the width dr in the section of the circular ring of the tool bit; the formula of the friction force and the torque borne by the circular ring surface infinitesimal element is four: dM = r μ dF, where μ is the coefficient of friction and dF is the positive pressure to which the torus infinitesimal is subjected; the positive pressure formula borne by the circular ring surface infinitesimal element is as the formula five: dF = PdS, wherein P is the pressure applied to the torus, and dS is the infinitesimal area; the formula of the infinitesimal area is six: dS =2 π rdr; the pressure intensity of the circular ring surface is expressed by the formula seven: p = F/π (R) 2 −R' 2 ) Wherein F is the axial pretightening force, R is the excircle radius of the section of the circular ring of the cutter head, and R' is the excircle radius of the section of the circular ring of the cutter head; substituting the formula six and the formula seven into the formula five, substituting the formula five into the formula four, and substituting the formula four into the formula three, wherein the formula eight can be calculated: m f =2μF(R 3 −R' 3 )/3(R 2 −R' 2 ). Substituting formula two and formula eight into formula one to obtain M f =2μF(R 3 −R' 3 )/3(R 2 −R' 2 )= 0.8M F_max =0.8 F t_max R, obtaining a calculation formula nine of the axial pretightening force F from the formula: f =1.2F t_max R(R 2 −R' 2 )/μ(R 3 −R' 3 ). That is, in order to reduce the peak value of the tangential milling force and ensure that the damping gasket can effectively perform compression damping near the peak value of the tangential milling force, the magnitude of the axial pretightening force F applied to the self-locking screw 9 is 1.2F t_max R(R 2 −R' 2 )/μ(R 3 −R' 3 )。
Preferably, the height of the cutting head 1 is as small as possible without interfering with the cutting process to increase the tool stiffness.
Preferably, the diameter of the cutter head cavity 5 is 1mm to 2mm larger than that of the self-locking screw 9.
Preferably, the cutter bar thread inner hole 8 and the self-locking screw 9 can be matched with each other to generate self-locking action.
Preferably, the cutter head connecting teeth 6 and the cutter bar connecting teeth 7 are the same in size, the cross sections of the cutter head connecting teeth and the cutter bar connecting teeth are fan-shaped, the cutter head connecting teeth and the cutter bar connecting teeth are uniformly distributed along the circumferential direction, the cutter head connecting teeth and the cutter bar connecting teeth can be inserted into the cutter head connecting teeth and the cutter bar connecting teeth, and the height of the connecting teeth is 20 mm-30mm.
Preferably, the side surface clearance after the cutter head connecting tooth 6 and the cutter bar connecting tooth 7 are inserted into each other is 1mm to 2mm, so that the damping gasket 3 is placed in the clearance.
Preferably, the damping gasket 3 is made of damping alloy or rubber.
Preferably, the cutter head 1 and the cutter bar 2 are made of tool steel or hard alloy.
Preferably, the self-locking screw 9 and the washer 10 are made of carbon steel or stainless steel.
Preferably, the maximum value of the tangential milling force in the milling process is obtained by theoretical calculation of the milling force;
preferably, the maximum value of the tangential milling force in the milling process is obtained from historical milling force monitoring data in the previous process.
The above steps will be described in detail below with reference to fig. 1-2, according to one embodiment of the present application.
The self-locking screw is characterized in that a workpiece material is TC4 titanium alloy, the axial cutting depth is 0.5mm, the radial cutting depth is 15mm, the feeding speed is 1500mm/min, the rotating speed of a main shaft is 1200r/min, tool steel is adopted as tool steel for a tool bit and a tool bar, the friction coefficient of the tool steel under the condition of lubrication is 0.1, the outer diameter of a circular axial end face is 19mm, the inner diameter of the circular axial end face is 7mm, 5 teeth with the same size are adopted as a tool bit connecting tooth and a tool bar connecting tooth, the diameter of the self-locking screw is 6mm, the relation between the tightening torque T of the self-locking screw and the axial pre-tightening force F is measured by a strain gauge through a strain method, the F and the T are approximately in a direct proportion relation, data are fitted, and the size relation between the F and the T is: f =600T, the change of the tangential milling force of milling with the non-vibration-damping milling cutter along with the rotation angle of the cutter is shown in FIG. 3, namely F t_max =608N, and the tangential milling force peak to peak phase is 90 °, cutting chatter is easily caused.
And (4) bringing the specific numerical value into nine, solving to obtain axial pretightening force F =6639N, and tightening the self-locking screw by using the torque T =11N · m. A constant-torque wrench is adopted to tighten a self-locking screw with torque of 11 N.m, so that the tangential milling force of the split damping vibration-damping milling cutter in milling processing is obtained, the change of the tangential milling force along with the rotation angle of a cutter is shown in figure 4, the maximum value of the tangential milling force in milling processing is 566N, and because the split damping vibration-damping milling cutter exceeds the specified torque in the milling process, a cutter head and a cutter bar generate relative displacement to compress a damping gasket, so that a plurality of wave crests appear in the tangential milling force when a single blade cuts into and cuts out a workpiece, the standard 90-degree phase between the wave crests of the tangential milling force is disturbed, namely, the frequency of the tangential milling force is disturbed, and the cutting chatter is restrained.
The results show that the split damping milling cutter for machining the valve body disclosed by the invention has the advantages that by reasonably setting the pre-tightening force, when the split damping milling cutter exceeds a specific torque in the milling process, the cutter head and the cutter bar generate relative displacement to compress the damping gasket, so that the impact vibration of the cutter is inhibited, and the risk of blade tipping is reduced; meanwhile, the frequency of milling force can be disturbed, cutting vibration is restrained, machining quality is improved, and in addition, the service life of the damping gasket is prolonged while the vibration reduction effect is guaranteed by damping specific impact.
While the embodiments of the invention have been described in detail in connection with the accompanying drawings, it is not intended to limit the scope of the invention. Various modifications and changes may be made by those skilled in the art without inventive work within the scope of the appended claims.
Claims (7)
1. The utility model provides a split type damping vibration attenuation milling cutter for valve body processing which characterized in that includes: the cutter comprises a cutter head, a cutter rod, a cutter blade and a connecting piece; the cutter head and the cutter bar are of cylindrical structures, the sections of the cutter head and the cutter bar are circular sections, the cutter head and the cutter bar are coaxially arranged, the tail part of the cutter head is connected to the head part of the cutter bar, and the plurality of blades are circumferentially arranged at the head part of the cutter head;
the cutter head is provided with a cutter head cavity, the cutter head cavity penetrates through the cutter head along the axis direction of the cutter head, the tail of the cutter head is provided with cutter head connecting teeth, a plurality of cutter head connecting teeth are circumferentially distributed at intervals along the circular section of the tail of the cutter head, and the adjacent two sides of any one cutter head connecting tooth are provided with cutter head connecting grooves;
a cutter bar threaded inner hole is formed in the axis position of the cutter bar, the cutter bar threaded inner hole extends from the head of the cutter bar to the tail of the cutter bar along the axis of the cutter bar, the cutter bar threaded inner hole is a blind hole, cutter bar connecting teeth are arranged at the head of the cutter bar, a plurality of cutter bar connecting teeth are circumferentially distributed at intervals along the circular cross section of the head of the cutter bar, and a cutter bar connecting groove is formed in each two adjacent sides of any one of the cutter bar connecting teeth;
the tail part of the cutter head is in plug fit with the head part of the cutter bar, the cutter bar connecting tooth is plugged in the cutter bar connecting groove, and the cutter bar connecting tooth is plugged in the cutter bar connecting groove; after the cutting-in, the two sides of any cutter bar connecting tooth are cutter bar connecting teeth, and the two sides of any cutter bar connecting tooth are cutter bar connecting teeth; after the insertion, gaps are reserved on the side surfaces of the adjacent cutter head connecting teeth and the cutter bar connecting teeth, and damping gaskets are placed in the gaps; the cutter head connecting teeth and the cutter bar connecting grooves are connected and matched with each other to form a plurality of axial end faces at the connecting and matching positions of the cutter head connecting grooves and the cutter bar connecting teeth;
the connecting piece comprises a self-locking screw and a gasket, and the self-locking screw penetrates through the gasket, the cutter head cavity and the cutter bar thread inner hole at the head part of the cutter bar; axial pretightening force is applied to the self-locking screw, and the annular axial end face at the joint and matching part of the cutter head and the cutter bar generates static friction force under the action of the axial pretightening force; determining the axial pretightening force for fastening the self-locking screw according to the tangential milling force in the machining process, so that when the torque generated by the tangential milling force exceeds the maximum static friction torque generated by the axial pretightening force, the cutter head and the cutter bar rotate relatively, and the adjacent cutter head connecting teeth and the cutter bar connecting teeth extrude damping gaskets in gaps; in order to ensure that the damping gasket is compressed and damped near the moment when the tangential milling force reaches the peak value and accurately reduce the peak value of the tangential milling force, the axial pretightening force F is 1.2F t_max R(R 2 −R' 2 )/μ(R 3 −R' 3 ) Wherein F is t_max The maximum value of the tangential milling force in milling processing is shown, R is the excircle radius of the section of the circular ring of the cutter head, R' is the inner circle radius of the section of the circular ring of the cutter head, and mu is a friction coefficient.
2. The split damping vibration-damping milling cutter for valve body machining according to claim 1,maximum value of tangential milling force F in milling t_max The milling force monitoring method is obtained by theoretical calculation of cutting force or historical milling force monitoring data in previous processing.
3. The split damping vibration attenuation milling cutter for valve body machining according to claim 2 is characterized in that the axial pretightening force F is determined by the following method:
controlling the maximum torque M which can be generated by the static friction force of the cutter head and the cutter bar under the action of the axial pretightening force F f The maximum value M of the torque generated by the tangential milling force in the milling process is achieved F_max When the cutting edge is 0.8 times, the cutter head connecting tooth and the cutter bar connecting tooth generate relative rotation to reduce the peak value of tangential milling force, namely M f And M F_max The requirements are as follows: m is a group of f =0.8M F_max ；
Maximum torque M generated by tangential milling force in milling F_max The calculation formula of (2) is as follows: m F_max =F t_max R, wherein F t_max The maximum value of the tangential milling force in milling processing is shown, and R is the excircle radius of the circular section of the tool bit;
maximum torque M generated by static friction force of tool bit and tool bar under axial pretightening force f The calculation formula of (c) is:
wherein R' is the radius of the inner circle of the circular section of the tool bit, and dM is the friction torque borne by the circular surface infinitesimal with the radius R and the width dr in the circular section of the tool bit;
the formula of the friction force and the torque borne by the circular ring surface infinitesimal element is as follows: dM = r μ dF, where μ is the coefficient of friction and dF is the positive pressure to which the toroid element is subjected;
the positive pressure on the micro elements of the circular ring surface is expressed by the following formula: dF = PdS, wherein P is the pressure applied to the torus, and dS is the infinitesimal area;
the infinitesimal area formula is: dS =2 π rdr;
the pressure intensity of the circular ring surface is expressed by the following formula: p = F/π (R) 2 −R' 2 ) Wherein F is the axial pretightening force, R is the excircle radius of the section of the cutter head ring, and R' is the section of the cutter head ringThe radius of an in-plane circle;
then it can be calculated to get: m f =2μF(R 3 −R' 3 )/3(R 2 −R' 2 )= 0.8M F_max =0.8 F t_max R；
The calculation formula of the axial pretightening force F can be obtained: f =1.2F t_max R(R 2 −R' 2 )/μ(R 3 −R' 3 )。
4. The split damping milling cutter for valve body machining according to claim 3, wherein the cutter head height is as small as possible without interfering with the cutting process to increase the cutter stiffness.
5. The split damping milling cutter for machining the valve body according to claim 4, wherein the diameter of the cavity of the cutter head is 1mm to 2mm larger than that of the self-locking screw.
6. The split damping milling cutter for machining the valve body according to claim 5, wherein the damping gasket is made of damping alloy or rubber.
7. The split damping and vibration damping milling cutter for valve body machining according to claim 6, wherein the cutter head and the cutter bar are made of tool steel or hard alloy, and the self-locking screw and the gasket are made of carbon steel or stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210990862.8A CN115229253A (en) | 2022-08-18 | 2022-08-18 | Split type damping vibration attenuation milling cutter for valve body machining |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210990862.8A CN115229253A (en) | 2022-08-18 | 2022-08-18 | Split type damping vibration attenuation milling cutter for valve body machining |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115229253A true CN115229253A (en) | 2022-10-25 |
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ID=83678834
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210990862.8A Pending CN115229253A (en) | 2022-08-18 | 2022-08-18 | Split type damping vibration attenuation milling cutter for valve body machining |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115229253A (en) |
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2022
- 2022-08-18 CN CN202210990862.8A patent/CN115229253A/en active Pending
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