CN109332801B - Optimization method for efficiently and stably broaching turbine disc mortise - Google Patents
Optimization method for efficiently and stably broaching turbine disc mortise Download PDFInfo
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- CN109332801B CN109332801B CN201811327430.9A CN201811327430A CN109332801B CN 109332801 B CN109332801 B CN 109332801B CN 201811327430 A CN201811327430 A CN 201811327430A CN 109332801 B CN109332801 B CN 109332801B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D37/00—Broaching machines or broaching devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D41/00—Broaching machines or broaching devices characterised only by constructional features of particular parts
- B23D41/08—Broaching machines or broaching devices characterised only by constructional features of particular parts of drives; of control devices
Abstract
The invention discloses an optimization method for efficiently and stably broaching turbine disc mortises, which comprises the following steps: according to the broaching path, between the contact tracks of the workpiece and the toolUniformly arranging a series of points at intervals, and sequentially obtaining modal transfer functions of nodes of the cutter and the workpiece through a modal test; establishing a transfer function phi between workpieces with different nodes and the cutter through the modal transfer function of each node of the cutter and the modal transfer function of each node of the workpiece1iWill phi1iObtaining a transfer function phi in Laplace form through Laplace transformation1i(s); according to phi1i(s) obtaining stable regions in the cutting process of different nodes of the workpiece by a method of solving the stable regions through a frequency domain; and carrying out efficient and stable machining on the workpiece according to the cutting parameters of the stable region. The invention can select corresponding cutting parameters according to different nodes, stably and efficiently process, avoid the occurrence of cutter chattering to cause cutter edge breakage, and improve the service life of the cutter and the surface quality of a workpiece.
Description
Technical Field
The invention relates to the field of machining, in particular to an optimization method for efficiently and stably broaching a turbine disc mortise.
Background
Currently, broaching machining is taken as a special and effective machining method, and has the advantages that other machining modes are not comparable in machining parts with a plurality of specific structures, such as high machining efficiency, high machining precision and the like. The nickel-based alloy is used as a general turbine disc mortise material, and has the characteristics of difficult chip breakage, large cutting force, short service life of a cutter and the like in the cutting process due to the characteristics of the nickel-based alloy in the machining process, and the defects of large machining error, shortened service life of the cutter, low machining efficiency and the like due to the fact that the broach is long in the broaching process and the mounting rigidity is limited by the workpiece fixing mode of the broaching process are added, and in addition, the contact position of the cutter and the workpiece is changed in the broaching process, the contact point is also changed in the response of the part, namely the dynamic characteristic of the cutter is changed, and the stable area of the cutting process is changed. If the cutting speed is not changed in time or the cutting depth is not proper, the cutter is easy to shake, the cutter is broken, the surface quality of a workpiece is reduced, and the like.
Disclosure of Invention
The present invention aims to solve the above technical problem at least to some extent. Therefore, the invention provides an optimization method for efficiently and stably broaching the turbine disc mortise.
The technical scheme adopted by the invention for solving the technical problems is as follows: an optimization method for efficiently and stably broaching turbine disc mortises comprises the following steps:
s1, arranging a series of points uniformly spaced on the contact path of the workpiece and the tool according to the broaching path, and sequentially marking as: 1, 2, 3, …, k, sequentially obtaining modal transfer functions of each node of the cutter and the workpiece through a modal test, and setting the modal transfer functions as follows: h1i(ω1)，H2i(ω1)，i＝1，2，3，…，k；
S2, establishing a transfer function phi between the workpiece and the cutter with different nodes through the modal transfer function of each node of the cutter and the modal transfer function of each node of the workpiece1iWill phi1iObtaining a transfer function phi in Laplace form through Laplace transformation1i(s)；
S3, according to phi1i(s) obtaining stable regions in the cutting process of different nodes of the workpiece by a method of solving the stable regions through a frequency domain;
and S4, performing efficient and stable machining on the workpiece according to the cutting parameters of the stable region.
Further, the pitch between the adjacent dots in the step S1 is 1 to 2 mm.
Further, said H1i(ω1) And H2i(ω1) Are obtained by laplace transformation of the cutting kinetics equation.
Further, the cutting kinetics equation is:
wherein q is1，q2Respectively the displacement of the workpiece and the cutter from the ideal position,
respectively the speed at which the workpiece and the tool deviate from the ideal position,
acceleration of the workpiece and tool away from the ideal position, M1，M2Modal masses, C, of workpiece and tool, respectively1，C2Damping values, K, of the workpiece and the tool, respectively1，K2Stiffness of the workpiece and the tool, respectively, F1(t)，F2(t) the cutting forces applied to the workpiece and the tool are a pair of reaction forces, and the relationship is as follows: f2(t)＝-F1(t)；
And (3) obtaining a cutting kinetic equation after Laplace transformation:
further, in said S2, Φ will be1jThe following formula is obtained by laplace transform:
wherein h(s) is by dynamic depth of cut hi(t) is obtained by Laplace transform, h0For the desired depth of cut in the cut, T is the period of the cut, αpTo cut the width, k2The coefficient of cutting force under the ultrasonic vibration assistance condition.
Further, h isi(t) the relationship is as follows:
hi(t)＝h0-[(h2i(t)-h1i(t))-(h2i(t-T)-h1i(t-T))]；
wherein h is1i(t) is the depth of cut after the tool has deviated from the ideal depth of cut due to the influence of vibration, h2iAnd (t) is the cutting depth after deviating from the ideal cutting depth after the workpiece vibration influences.h2i(T-T) depth of cut, h, of the preceding tooth after deviating from the ideal depth of cut after influence of workpiece vibration1i(T-T) tool vibration affects the depth of cut of the previous tooth after the back has deviated from the desired depth of cut. Further, the workpiece is connected with an ultrasonic vibration auxiliary system and fixed on the workbench, the ultrasonic vibration auxiliary system comprises an ultrasonic vibration amplitude transformer, a piezoelectric actuator capable of generating ultrasonic vibration is mounted on the ultrasonic vibration amplitude transformer, the piezoelectric actuator is connected with an ultrasonic generator, and the ultrasonic generator is connected with a power supply.
Further, when the broaching machine can adjust the machining speed in real time when the workpiece is machined in step S4, the maximum cutting depths of different nodes are selected according to the stable region functions of the different nodes in the contact path between the workpiece and the tool, the tooth lift of the broaching tool is manufactured according to the maximum cutting depths in consideration of the allowable broaching speed range of the machine tool, and during machining, the maximum broaching speeds of the different nodes are formed according to the determined maximum tooth lift and the maximum broaching speed of each node, and machining is performed according to the maximum broaching speeds of the different nodes, thereby achieving efficient machining.
Further, when the broaching machine processing speed is constant, the broaching speed and the manufacturing broach are selected according to the stable region function of different nodes in the contact path of the workpiece and the broach according to the step S4, and the tooth lift of the manufacturing broach corresponds to the cutting depth. According to the material cutting efficiency and the maximum broaching speed allowed by the machine tool, the broaching speed and the corresponding cutting depth are selected in the stable region functions of different nodes to manufacture the broaching tool, so that the high-efficiency machining is realized.
The invention has the beneficial effects that: according to the dynamic characteristic of the contact position of the broach and the workpiece, a stable region of broaching along with the change of a machining path is obtained, cutting parameters under different nodes are selected according to the stable regions under the different nodes, stable and efficient machining is carried out, the occurrence of tool chattering is avoided, the tool tipping is avoided, the service life of the tool is prolonged, and the surface quality of the workpiece is improved.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a schematic view of the attachment of a first attachment member to a vibrating horn;
FIG. 2 is a schematic view of the construction of a vibrating horn;
FIG. 3 is a sectional view showing a coupling structure of the first coupling member, the vibration horn, and the second coupling member;
FIG. 4 is an enlarged view taken at A of FIG. 1
Detailed Description
The present invention will be described in detail with reference to examples.
The invention discloses an optimization method for efficiently and stably broaching turbine disc mortises, which comprises the following steps:
s1, arranging a series of points uniformly spaced on the contact path of the workpiece and the tool according to the broaching path, and sequentially marking as: 1, 2, 3, …, k, sequentially obtaining modal transfer functions of each node of the cutter and the workpiece through a modal test, and setting the modal transfer functions as follows: h1i(ω1)，H2i(ω1)，i＝1，2，3，…，k；
S2, establishing a transfer function phi between the workpiece and the cutter with different nodes through the modal transfer function of each node of the cutter and the modal transfer function of each node of the workpiece1iWill phi1iObtaining a transfer function phi in Laplace form through Laplace transformation1i(s)；
S3, according to phi1i(s) obtaining stable regions in the cutting process of different nodes of the workpiece by a method of solving the stable regions through a frequency domain;
and S4, performing efficient and stable machining on the workpiece according to the cutting parameters of the stable region.
The pitch between adjacent dots in the step S1 is 1 to 2 mm. Said H1i(ω1) And H2i(ω1) Is obtained by Laplace transform of cutting dynamics equation, and transfer function phi1i(s) is phi1iObtained by laplace transform. The calculation process thereof is described in detail below.
During broaching, the contact position of the tool and the workpiece changes, and the contact point of the tool and the workpiece also changes in response of the part, namely the dynamic characteristic of the tool changes, so that the stable area of cutting machining changes. If the cutting speed is not changed in time or the cutting depth is not proper, the cutter is easy to shake, the cutter is broken, the surface quality of a workpiece is reduced, and the like.
The kinetic equation in the cutting processing system is as follows:
wherein: q. q.s1，q2Respectively the displacement of the workpiece and the cutter from the ideal position,
respectively the speed of the workpiece and the cutter deviating from the ideal position,
respectively the acceleration of the workpiece and the tool away from the ideal position. M1，M2Modal masses, C, of workpiece and tool, respectively1，C2Damping values, K, of the workpiece and the tool, respectively1，K2Stiffness of the workpiece and the tool, respectively, F1(t)，F2(t) are the cutting forces to which the workpiece and the tool are subjected, respectively. M1、M2、C1、C2、K1、K2Can be obtained by finite element software calculation. F1(t)，F2(t) is a pair of reaction forces, so the relationship is as follows:
F2(t)＝-F1(t)
and the relation between the cutting force and the cutting depth and width is as follows:
F2(t)＝k2·hi(t)·ap
hi(T) is the dynamic depth of cut, T is the cutPeriod, αpTo cut the width, k2Is the coefficient of cutting force, k, under the assistance of ultrasonic vibration2The cutting depth can be obtained by right-angle cutting tests at different cutting depths and fitting the test data.
The dynamic cutting thicknesses of different nodes are as follows:
hi(t)＝h0-[(h2i(t)-h1i(t))-(h2i(t-T)-h1i(t-T))]
the cutting depth h is laplace transformed to obtain:
h(s)＝h0-(e-sT-1)(h2(s)-h1(s))
wherein h is0Ideal depth of cut in cutting, hi(t) corresponding laplace transform to h(s); h is1i(t) is the depth of cut after the tool vibration has affected the deviation from the ideal depth of cut, the corresponding Laplace transform is h1(s)；h2i(t) is the depth of cut after the workpiece has deviated from the ideal depth of cut under the influence of vibration, and the corresponding Laplace transform is h2(s)。h2i(T-T) depth of cut, h, of the preceding tooth after deviating from the ideal depth of cut after influence of workpiece vibration1i(T-T) tool vibration affects the depth of cut of the previous tooth after the back has deviated from the desired depth of cut.
The different nodal cutting kinetic equations in the contact path of the tool and the workpiece are as follows:
according to the broaching machining path, respectively arranging a point on the contact track of the workpiece and the tool at intervals of 1-2mm, and sequentially marking as: 1, 2, 3, …, k. According to the formula, through a modal test, the modal (transfer) functions of the nodes of the cutter and the workpiece are sequentially obtained and are set as follows: h1i(ω1)，H2i(ω1)，i＝1，2，3，…，k。
In the cutting process, under the action of cutting force, the transfer functions between the workpieces with different nodes and the cutter are as follows:
Φ1i＝H1i(ω1)+H2i(ω1)
Φ1iis transformed into phi by Laplace1i(s) the relationship is as follows:
according to the method for solving the stable region in the frequency domain, the stable region in the cutting process under different nodes of the workpiece and the cutter is solved:
when the broaching machine can adjust the machining speed in real time, the maximum cutting depth of different nodes is selected according to the stable region function of the different nodes in the contact path of the workpiece and the cutter, and the tooth lifting amount of the broaching machine is manufactured according to the maximum cutting depth by considering the allowable broaching machining speed range of the machine tool. In the machining, according to the determined maximum tooth lifting amount, the maximum broaching speed under each node is selected to form the maximum broaching speeds under different nodes, and the machining is carried out according to the maximum broaching speeds under different nodes, so that the high-efficiency machining is realized. Generally, a machine tool cannot adjust the machining speed in real time in machining, for example, the rotating speed is 8000rpm/min, the rotating speed is 10000rpm/min at a node position adjacent to the machine tool according to the machining requirement, and the speed cannot be adjusted from 8000rpm/min to 10000rpm/min in the machining process due to the reasons of rigidity of the machine tool and the like, and cutting machining (such as no cutting depth or no feeding) is suspended, the rotating speed is increased to 10000rpm/min, and then cutting machining is carried out.
When the broaching machine can not adjust the processing speed in real time, the broaching speed and the manufacturing broaching tool are selected according to the stable region function of different nodes in the contact path of the workpiece and the tool and according to the highest material cutting efficiency. According to the material cutting efficiency V ═ ap× v and machine toolThe allowable maximum broaching speed is selected as a function of stable regions of different nodes, and the broaching speed and the corresponding cutting depth (tooth lifting amount of cutter teeth in the broaching tool) are selected to manufacture the broaching tool, so that the high-efficiency machining is realized.
The processing machine tool is a vertical or horizontal broaching machine and comprises a workbench, a cutter, a guide sleeve, a hydraulic system and the like; the control system consists of a control system of the machine tool and an ultrasonic vibration control system; the ultrasonic vibration auxiliary system consists of a vibration amplitude transformer, a piezoelectric actuator, a power supply and an ultrasonic generator, wherein the piezoelectric actuator is arranged on the vibration amplitude transformer, and can reduce cutting force by an ultrasonic vibration auxiliary processing mode and realize stable and efficient broaching processing. The workpiece is connected with the ultrasonic vibration auxiliary system and is fixed on the workbench, and the workpiece is connected with the vibration amplitude transformer to obtain ultrasonic vibration. During broaching, the contact position of the tool and the workpiece changes, and the contact point of the tool and the workpiece also changes in response of the part, namely the dynamic characteristic of the tool changes, so that the stable area of cutting machining changes. If the cutting speed is not changed in time or the cutting depth is not proper, the cutter is easy to shake, the cutter is broken, the surface quality of a workpiece is reduced, and the like. The machining method can perform corresponding change of cutting parameters along with the change of the machining path and the stable area, perform stable and efficient machining, avoid tool chatter, avoid tool tipping, and improve the service life of the tool and the surface quality of a workpiece.
The main structure of the ultrasonic vibration assisting system is specifically described below with reference to fig. 1 to 4.
The ultrasonic vibration auxiliary system comprises a first connecting piece 1 and a vibration amplitude transformer 2, wherein one end of the vibration amplitude transformer 2 is arranged in the first connecting piece 1, the other end of the vibration amplitude transformer extends out of the first connecting piece 1 and is fixedly connected with a workpiece, and the vibration amplitude transformer 2 is provided with a pair of piezoelectric actuators for generating axial vibration and transmitting the vibration to the workpiece. The workpiece is clamped at the end part of the vibration amplitude transformer 2, and the first connecting piece 1 is fixed on the workbench.
The structure of the vibration horn will be described in detail below.
The first connecting part 1 is provided with an inner cavity 11, and the inner cavity 11 extends along the axis of the outer ring thereof. The vibration amplitude transformer 2 is inserted in the inner cavity 11, and the axis of the vibration amplitude transformer coincides with the axis of the outer ring of the first connecting piece 1 or the inner cavity 11. The cross section of the inner cavity 11 can be circular or diagonal, in order to make the vibration horn 2 rotate randomly, the cross section of the inner cavity 11 in this embodiment is polygonal for transmitting and bearing the torsion moment, preferably, the cross section of the inner cavity 11 is regular hexagon, and the rigidity can be kept to be the maximum when the external condition is fixed.
The vibration amplitude transformer 2 is made of titanium alloy, so that the material loss in working frequency is low, the fatigue resistance is high, the acoustic impedance is low, and the vibration amplitude transformer can bear larger vibration speed and displacement amplitude. The stepped vibration amplitude transformer 2 has great stress concentration at the abrupt change position of the section, and the problem of fracture caused by fatigue is easy to occur at the position close to the abrupt change position, so that the stress concentration value can be reduced by adopting a Gaussian curve, arc and cone line transition at the abrupt change position. The tail end of the vibration amplitude transformer is in 1 Gaussian curve transition at the transition position, the diameter of the section with the smaller cross section area is about 1/2 of the section with the larger diameter, the length of the section with the smaller cross section area is about 2/3 of the section with the larger cross section area, and the principle that the tail end adopts 1 Gaussian curve transition firstly improves the service life of the vibration amplitude transformer so that the vibration amplitude transformer is in an equal stress state.
As shown in fig. 3 and 4, the vibration horn 2 includes a fitting positioning section 21, a first connecting section 22, a second connecting member mounting section 23, an actuator mounting section 24, a third connecting member mounting section 25, and a workpiece clamping section 26, which are sequentially provided. The first connecting piece mounting section 22, the second connecting piece mounting section 23, the actuator mounting section 24 and the third connecting piece mounting section 25 are all cylindrical, the diameter of the second connecting piece mounting section 23 is reduced by 0.1-0.15mm compared with that of the first connecting piece mounting section 22, and the second connecting piece mounting section 23 is positioned at a vibration mode node position of the vibration amplitude transformer. The matching positioning section 21 and the workpiece clamping section 26 are located at two ends of the vibration amplitude transformer 2, and the workpiece clamping section 26 is used for clamping workpieces. The matching positioning section 21 is connected with the bottom of the inner cavity 11 in a matching mode, preferably, a circular groove is formed in the bottom of the inner cavity 11, a first gasket 12 is installed at the circular groove, a conical groove is formed in the outer end of the first gasket 12, the matching positioning section 21 is a cone and matched with the conical groove, the taper of the cone is 1:8, the matching positioning section 21 is inserted into the conical groove and installed in the conical groove, the matching positioning section 21 and the first gasket 12 are used for transmitting and bearing axial loads, the first gasket 12 is made of glass fibers and PET in a composite mode according to a sandwich layer structure, the middle portion of the first gasket is PET, and the inner portion and the outer portion of the first gasket.
In this embodiment, in order that the second connector 231 can transmit torque, preferably, a polyhedron connection is adopted to transmit torque, an outer ring of the cross section of the second connector 231 is a polygon matched with the inner cavity 11, and the cross section of the inner ring of the cross section of the second connector 231 and the cross section of the second connector mounting section 23 are polygons matched with each other, and the cross section is non-circular and can transmit torque. The second connector 231 is fixedly connected with the first connector 1, preferably, the section inner ring of the second connector 231 and the section of the second connector mounting section 23 are regular octagons, and the section outer ring of the second connector 231 is a regular hexagon. Further, the connection mode of the second connection member 231 and the first connection member 1 is preferably that the second connection member 231 and the first connection member 1 are provided with corresponding bolt holes so as to be fixed and pre-tightened through bolt connection, the number of the bolts is specifically three, the bolt holes of the second connection member 231 are blind holes, and a first washer 232 is mounted between the second connection member 231 and the second connection member mounting section 23. The first gasket 232 is in a regular octagon shape in cross section and is formed by compounding glass fibers and PET according to a sandwich layer structure, the PET is arranged in the middle, the glass fibers are arranged inside and outside, the high elastic modulus and the lubricating effect are achieved, and fatigue damage is not easily caused in the process that the vibration amplitude transformer is repeatedly twisted. The shaft diameter of the second connecting piece mounting section 23 is 0.1-0.2mm less than that of the first connecting section 22.
The second connecting member 231 is provided with a break-off portion, the break-off portion is provided with a second gasket 233, one end of the second gasket 233 is in contact with the first gasket 232, and the other end of the second gasket 233 is in contact with the first connecting member 1, specifically, as shown in fig. 4, the cross-sectional shape of the second gasket 233 is formed by splicing two right-angled folding blocks in opposite directions, and the splicing portion has a certain arc and an angle. This maintains a tight connection between the components while the bolt provides a compressive force toward the center. And the second gasket 233 has a damping property, and is capable of isolating vibration, i.e., isolating vibration of the vibration horn from the machine tool table, and likewise, preventing vibration of the machine tool from interfering with vibration of the vibration horn.
The axial diameter of the actuator mounting section 24 is about 1/2 of the second connector mounting section 23, the piezoelectric actuator 6 is mounted on the actuator mounting section 24, the piezoelectric actuator 6 is used for realizing the axial resonance vibration of the vibration amplitude transformer, the piezoelectric actuator 6 is connected with the ultrasonic generator through an electric wire, the transmission of vibration frequency signals is transmitted through the wireless transmitter and the wireless receiver and is coded and decoded by the coding mechanism, the piezoelectric actuator 6 is specifically an ultrasonic transducer, and the ultrasonic frequency electric energy generated by the ultrasonic generator is converted into the mechanical energy of the ultrasonic vibration. Preferably, the second connector mounting section 23 and the actuator mounting section 24 form a stepped shaft, the diameters of the first connector section 22 and the actuator mounting section 24 are sequentially reduced, and the actuator mounting section 24 is provided with a pair of mounting grooves at intervals in the radial direction for mounting and matching the piezoelectric actuator 6. After the piezoelectric actuator 6 is installed in the installation groove, the outer ring of the piezoelectric actuator is provided with a clamp spring 61 which is clamped and fixed, a step is arranged on the periphery of the clamp spring 61 close to the second connecting piece installation section 23, the step is a regular hexahedron and forms a second groove capable of being matched with and installing the second connecting piece 231 with the second connecting piece installation section 23, and therefore one part of the second connecting piece 231 is installed on the step of the clamp spring 61, namely, the clamp spring 61 is clamped and fixed, the piezoelectric actuator 6 is fixed more stably, and the step of the clamp spring 61 has a limiting effect on the second connecting piece 231.
The third connecting piece mounting section 25 is provided with a first groove 251, a third connecting piece 2511 is mounted between the first groove 251 and the outer wall of the inner cavity 11, the third connecting piece 2511 is fixedly connected with the first connecting piece 1, the outer ring of the section of the third connecting piece 2511 is matched with the inner cavity 11, and a circular gasket is arranged between the third connecting piece 2511 and the first groove 251. The second connecting member 231, the third connecting member 2511, the first washer, the circular washer and the snap spring 61 are made of a material having a high elastic modulus, and are snap-fitted into the vibration horn 2 by deformation.
The inner circle of the cross section of the third connecting element 2511 is circular, and preferably, two first grooves 251 and two third connecting elements 2511 are correspondingly arranged and are arranged at intervals along the axis. Wherein, the vibration mode node of the vibration amplitude transformer 2 coincides with the positions of the second connecting piece 231 and the two third connecting pieces 2511. During installation, the second connecting element 231 rotates 180 ° with one of the third connecting elements 2511, and the angular difference between the two third connecting elements 2511 is 180 °, so that the dynamic unbalance mass caused by the installation of the connecting elements is mainly reduced as much as possible.
In order to achieve a good vibration effect of the workpiece clamping section 26 and to ensure the transmission of axial vibrations as far as possible, an extension section 27 and an intermediate shaft section 28 are arranged in succession between the actuator mounting section 24 and the third connecting part mounting section 25. The central shaft section 28 has the largest diameter throughout the vibration horn for further uniform transmission of axial vibrations to the third connector mounting section 25. The lengths of the extension 27 and the intermediate shaft section 28 are specifically adjusted according to the actual requirements.
A second connecting section 29 is arranged between the third connecting piece mounting section 25 and the workpiece clamping section 26, and the second connecting section 29 is a cylindrical amplitude-variable steel taking a Gaussian curve as the appearance and is mainly used for achieving high vibration speed and small amplitude of axial vibration and meeting the requirements of high vibration speed and low amplitude of vibration, so that the cylindrical amplitude-variable steel has faster vibration speed in a certain vibration period and is used for exciting a working medium to generate higher speed, the processing efficiency is improved, and the requirements of the surface quality of a workpiece are met
The above embodiments are only for illustrating the technical solutions of the present invention and are not limited thereto, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the technical solutions of the present invention.
Claims (9)
1. An optimization method for efficiently and stably broaching a turbine disc mortise is characterized by comprising the following steps:
s1, arranging a series of points uniformly spaced on the contact path of the workpiece and the tool according to the broaching path, and sequentially marking as: 1, 2, 3, …, k, by modal testing, in turnObtaining a modal transfer function of each node of the cutter and the workpiece, and setting the modal transfer function as follows: h1i(ω1)，H2i(ω1)，i＝1，2，3，…，k；
S2, establishing a transfer function phi between the workpiece and the cutter with different nodes through the modal transfer function of each node of the cutter and the modal transfer function of each node of the workpieceliWill phi1iObtaining a transfer function phi in Laplace form through Laplace transformation1i(s)；
S3, according to phi1i(s) obtaining stable regions in the cutting process of different nodes of the workpiece by a method of solving the stable regions through a frequency domain;
and S4, performing efficient and stable machining on the workpiece according to the cutting parameters of the stable region.
2. The optimized method for efficiently and stably broaching the turbine disc mortise according to claim 1, wherein the method comprises the following steps: the pitch between adjacent dots in the step S1 is 1 to 2 mm.
3. The optimized method for efficiently and stably broaching the turbine disc mortise according to claim 1 or 2, wherein the method comprises the following steps: said H1i(ω1) And H2i(ω1) Are obtained by laplace transformation of the cutting kinetics equation.
4. The method for optimizing a high efficiency and stability broaching turbine disc mortise according to claim 3, wherein the cutting kinetic equation is as follows:
wherein q is1，q2Respectively the displacement of the workpiece and the cutter from the ideal position,
respectively the speed at which the workpiece and the tool deviate from the ideal position,
acceleration of the workpiece and tool away from the ideal position, M1，M2Modal masses, C, of workpiece and tool, respectively1，C2Damping values, K, of the workpiece and the tool, respectively1，K2Stiffness of the workpiece and the tool, respectively, F1(t)，F2(t) the cutting forces applied to the workpiece and the tool are a pair of reaction forces, and the relationship is as follows: f2(t)＝-F1(t)；
And (3) obtaining a cutting kinetic equation after Laplace transformation:
5. the method for optimizing a high efficiency stable broaching turbine disc mortise according to claim 4, wherein in the step S2, Φ is1iThe following formula is obtained by laplace transform:
wherein h(s) is by dynamic depth of cut hi(t) is obtained by Laplace transform, h0For the desired depth of cut in the cut, T is the period of the cut, αpTo cut the width, k2The coefficient of cutting force under the ultrasonic vibration assistance condition.
6. According to claim5 the optimization method for efficiently and stably broaching the turbine disc mortise is characterized in that h isi(t) the relationship is as follows:
hi(t)＝h0-[(h2i(t)-h1i(t))-(h2i(t-T)-h1i(t-T))]；
wherein h is1i(t) is the depth of cut after the tool has deviated from the ideal depth of cut due to the influence of vibration, h2i(t) is the depth of cut after deviating from the ideal depth of cut after the workpiece is vibrated, h2i(T-T) depth of cut, h, of the preceding tooth after deviating from the ideal depth of cut after influence of workpiece vibration1i(T-T) tool vibration affects the depth of cut of the previous tooth after the back has deviated from the desired depth of cut.
7. The optimized method for efficiently and stably broaching the turbine disc mortise according to claim 1, wherein the method comprises the following steps: the workpiece is connected with the ultrasonic vibration auxiliary system and is fixed on the workbench, the ultrasonic vibration auxiliary system comprises a vibration amplitude transformer, a piezoelectric actuator capable of generating ultrasonic vibration is mounted on the vibration amplitude transformer, the piezoelectric actuator is connected with an ultrasonic generator, and the ultrasonic generator is connected with a power supply.
8. The optimized method for efficiently and stably broaching the turbine disc mortise according to claim 1, wherein the method comprises the following steps: step S4, when the broaching machine can adjust the processing speed in real time, the maximum cutting depth of different nodes is selected according to the stable region function of different nodes in the contact path of the workpiece and the tool, the maximum broaching speed range of the machine tool is considered, the tooth lifting amount of the broaching tool is manufactured according to the maximum cutting depth, the maximum broaching speed under different nodes is formed according to the determined maximum tooth lifting amount and the maximum broaching speed under each node during processing, and the processing is carried out according to the maximum broaching speed under different nodes, thereby realizing high-efficiency processing.
9. The optimized method for efficiently and stably broaching the turbine disc mortise according to claim 1, wherein the method comprises the following steps: step S4, when the broaching machine processing speed is fixed, according to the stable region function of different nodes in the contact path of the workpiece and the cutter, the broaching speed and the manufacturing broaching tool are selected according to the highest material cutting efficiency, and according to the material cutting efficiency and the maximum broaching processing speed allowed by the machine tool, the broaching speed and the corresponding cutting depth are selected according to the stable region function of different nodes to manufacture the broaching tool, thereby realizing high-efficiency processing.
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| CN114378362B (en) * | 2021-12-13 | 2023-08-18 | 东方电气集团东方汽轮机有限公司 | Broaching process for mortises of rotor disk of gas turbine |
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| CN107649736B (en) * | 2017-08-24 | 2019-04-12 | 中南大学 | For processing the multistation straight-tooth broaching tool and its processing method of turbine disc mortise |
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