Precision mold surface milling equipment and method thereof

Abstract

The invention discloses precision mold surface milling equipment which comprises a milling machine, the milling machine comprises a machine body, a base is fixedly installed below the machine body, a workbench is installed on the base through a lifting table, a cross beam is installed on the machine body, and a milling head is installed on the cross beam. A main shaft is installed on the cross beam, a cutter base is fixedly installed below the main shaft through a connecting assembly, the cutter base comprises a cutter shaft, and a fixing disc is fixedly installed at the bottom end of the cutter shaft. The differential transmission device is used for driving the mounting seat to actively move downwards to complete automatic active compensation on the height change of the end surface of the bottom side of the milling cutter by virtue of the angular speed and rotating speed difference caused by differential transmission between the cutter shaft and the first transmission wheel; the rotating speed difference is positively correlated with the rotating speed of the cutter shaft, namely the rotating speed of the milling cutter; therefore, compared with a lifting platform for driving the workpiece to realize active compensation, the device has the advantages of low control difficulty and small error.

Description

Technical Field

[0001] The present invention relates to the technical field of milling machining, and particularly relates to a precision mold surface milling device and a method thereof. Background Art

[0002] A precision mold refers to a mold used for the production of precision workpieces. Milling machining has a relatively high productivity and is one of the commonly used methods in metal cutting machining. According to the different distribution methods of the cutting edges on the milling cutter, the milling methods can be divided into face milling and peripheral milling. Peripheral milling mainly cuts the surface of the workpiece through the continuous movement of the cutting edge of the milling cutter, and the cutting force is mainly concentrated on the side of the milling cutter. Therefore, it is suitable for machining to remove the surface material of the workpiece in a large area. Face milling mainly cuts the surface of the workpiece through the end face of the milling cutter. Therefore, it is more suitable for fine machining of a small area and has higher requirements for the accuracy and heat dissipation of the milling cutter. Therefore, in the surface machining of precision molds, face milling becomes the first choice due to its higher surface quality, rigidity, efficiency, and material adaptability.

[0003] During the process of milling the surface of a precision mold using the face milling method, as face milling progresses, affected by the wear caused by friction, the length of the milling cutter will gradually decrease, and the height of the bottom surface of the cutting edge used for milling at the bottom end of the milling cutter will gradually rise, thus affecting the quality and accuracy of the surface milling machining of the precision mold. In order to reduce the influence of the wear of the milling cutter on the quality and accuracy of the milling machining, it is necessary to actively compensate for the height change of the bottom side end face of the milling cutter. Generally, the installation height of the tool on the milling machine is fixed, and this compensation needs to be completed by driving the workpiece with a lifting table. Also, because the wear rate of the milling cutter is positively correlated with the rotational speed of the milling cutter, actively compensating through the lifting table will increase the control difficulty of the lifting table and there will be a large error. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem in the prior art that because the wear rate of the milling cutter is positively correlated with the rotational speed of the milling cutter, actively compensating for the height change of the bottom side end face of the milling cutter through a lifting table will increase the control difficulty of the lifting table and there will be a large error, and thus a precision mold surface milling device is proposed.

[0005] The present invention adopts the following technical solutions: A precision mold surface milling equipment comprises a milling machine, the milling machine comprises a bed, a base is fixedly installed below the bed, a workbench is installed on the base through a lifting platform, a crossbeam is installed on the bed, a spindle is installed on the crossbeam, a tool seat is fixedly installed below the spindle through a connecting assembly, the tool seat comprises a tool shaft, a fixed plate is fixedly installed on the bottom end of the tool shaft, a plurality of symmetrical connecting members are rotatably connected to the upper limit of the fixed plate, a mounting seat is installed between the plurality of connecting members, a tool fastening assembly is installed on the mounting seat, a gear is fixedly installed on the top end of the connecting member, a first transmission wheel is rotatably connected to the upper limit of the tool shaft, a tooth groove meshing with the gear is opened in the bottom end of the first transmission wheel, a threaded shaft is fixedly installed on the bottom end of the connecting member, a plurality of threaded grooves threadedly connected to the threaded shaft are opened in the mounting seat, and a differential transmission device for driving the first transmission wheel to rotate is fixedly installed on the surface of one side of the crossbeam.

[0006] The transmission gear of claim 1, wherein the first and second transmission gears are connected along the length of the first gear and the second gear is connected along the length of the first gear to abut against the rotation of the transmission gear.

[0007] Preferably, the support rod is a hydraulic cylinder, the active pulley is composed of a first fixed cone disk and a first movable cone disk, the driven pulley is composed of a second fixed cone disk and a second movable cone disk, the second transmission belt is a metal transmission belt, the first fixed cone disk is fixedly connected to the first rotating shaft, the first movable cone disk is fixedly connected to the second rotating shaft, a limiting groove is opened in the first fixed cone disk, the bottom end of the second rotating shaft is limitedly slidably connected in the limiting groove, the middle part of the knife shaft is a square rod, the second fixed cone disk is fixedly connected to the square rod, the second movable cone disk is limitedly slidably connected to the square rod, a spring is fixedly connected between the second fixed cone disk and the second movable cone disk, and the first fixed cone disk, the first movable cone disk, the second fixed cone disk, the second movable cone disk and the second transmission belt together constitute an adjustable transmission structure.

[0008] Preferably, a plurality of rotationally symmetric blades are fixedly installed on the bottom side surface of the first transmission wheel, and a plurality of symmetric empty grooves are formed on the fixed disk.

[0009] Preferably, the connection assembly includes two connection flange plates respectively fixedly connected to the bottom end of the main shaft and the top end of the cutter shaft. The two connection flange plates are fixedly connected by a plurality of bolt nuts. A positioning column is fixedly installed on one of the connection flange plates, and a positioning groove matching the guiding column is formed on the other connection flange plate.

[0010] Preferably, the tool fastening assembly includes a plurality of rotationally symmetric mounting grooves formed in the mounting seat. A sliding groove is formed on one side surface of each of the plurality of mounting grooves. A sliding block is slidably connected in the sliding groove in a limited manner. A pressing plate slidably connected in the mounting groove is fixedly connected to the sliding block. A threaded rod threadedly connected to the sliding block is rotatably connected in a limited manner on one inner side surface of the sliding groove.

[0011] Preferably, the bracket is L-shaped, and reinforcing plates are fixedly installed at the connection between the bracket and the first limiting plate and at its right angle.

[0012] A milling method for the precision mold surface milling equipment according to claim -, comprising the following steps: S1. When performing surface milling on the precision mold, first install the precision mold workpiece on the workbench, then place the tool into the mounting groove, and use an automatic screwdriver tool to rotate the threaded rod. Through the thread action, drive the sliding block to move towards the inner side of the sliding groove, drive the pressing plate to cooperate with the inner side wall of the mounting groove to squeeze and press the tool, and complete the fixed installation of the milling cutter tool. S2. Immediately afterwards, start the main shaft. The main shaft drives the tool holder fixedly connected thereto through the connection assembly to rotate. The cutter shaft rotates together with the tool holder. The cutter shaft drives the mounting seat to rotate together through the fixed disk and the connecting piece, drives the milling cutter to rotate, and then controls the lifting table to drive the workbench and the precision mold workpiece installed on the workbench to move, providing a feed motion, and uses the rotating milling cutter to perform end milling on the surface of the precision mold workpiece. S3. When performing end milling, the cutter shaft drives the driven pulley fixedly connected thereto to rotate. The driven pulley drives the driving pulley to rotate by means of the second transmission belt. The driving pulley drives the first rotating shaft fixedly connected thereto to rotate. The first rotating shaft then drives the first transmission wheel to rotate through the second transmission wheel and the first transmission belt. By starting and controlling the length of the support rod, the distance between the first fixed cone disk and the first movable cone disk is controlled and adjusted, thereby adjusting the meshing positions of the second transmission belt with the first fixed cone disk and the first movable cone disk. After the meshing positions of the second transmission belt with the first fixed cone disk and the first movable cone disk change, affected by the elastic force of the spring, the distance between the second fixed cone disk and the second movable cone disk will also change adaptively, thereby changing the meshing positions of the second transmission belt with the second fixed cone disk and the second movable cone disk, so that the transmission ratio between the driving pulley and the driven pulley changes. By controlling and changing the angular velocity difference between the cutter shaft and the first transmission wheel during rotation, relative rotation will exist between the fixed disk and the first transmission wheel. Under the action of the relative rotation, the first transmission wheel will drive the gear meshed and connected thereto to rotate around the center of the connecting member, thereby driving the connecting member and the threaded shaft to also rotate around the center of the connecting member. Combining the threaded connection between the threaded shaft and the threaded groove on the mounting seat, the mounting seat is driven to move downward actively to complete the automatic active compensation for the height change of the bottom end face of the milling cutter; S4. When the milling cutter is not in the end milling state, by starting and controlling the length of the support rod, the transmission ratio between the driving pulley and the driven pulley is changed, so that the angular velocities of the two are the same, and thus the angular velocities of the cutter shaft and the first transmission wheel are the same. At this time, no active compensation is performed.

[0013] The beneficial effects of the present invention are as follows: 1. By means of the differential transmission device, the angular velocity and rotational speed difference caused by the differential transmission between the cutter shaft and the first transmission wheel drive the mounting seat to move downward actively to complete the automatic active compensation for the height change of the bottom end face of the milling cutter. Since the rotational speed difference is positively correlated with the rotational speed of the cutter shaft, that is, the rotational speed of the milling cutter, compared with the active compensation realized by the lifting table driving the workpiece, it has the advantages of low control difficulty and small error; 2. By means of the adjustable transmission structure composed of the first fixed cone disk, the first movable cone disk, the second fixed cone disk, the second movable cone disk and the second transmission belt, the progress of active compensation can be adjusted accordingly according to the different materials of the precision mold workpiece, so that the present invention can be applied to the active compensation for the wear of the milling cutter during the end milling of precision molds with different materials; 3. With the help of the adjustable transmission structure, the differential transmission device can be adjusted to the corresponding differential transmission state, that is, the active compensation state, only during milling processing. The differential transmission device is adjusted to a synchronous state in which the angular velocity of the cutter shaft and the first transmission wheel are the same at the rest of the time. No active compensation is performed in this state, which can significantly reduce the error caused by unnecessary active compensation during end milling, while active compensation is still performed under the action of the differential transmission device.

[0014] 4. When the first transmission wheel rotates, the first transmission wheel drives multiple blades to rotate, and cooperates with the empty slots on the fixed disk to generate an airflow that quickly passes through the empty slots and blows toward the mounting seat, which helps to improve the heat dissipation efficiency of the milling cutter during the milling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of a precision mold surface milling device proposed by the present invention; Figure 2 A schematic structural diagram of a tool holder for a precision mold surface milling device proposed by the present invention; Figure 3 A schematic diagram of the structure of a cutter shaft of a precision mold surface milling device proposed by the present invention; Figure 4 This is a schematic diagram of the bottom structure of a first transmission wheel of a precision mold surface milling device proposed by the present invention; Figure 5 A structural schematic diagram of a threaded shaft of a precision mold surface milling device proposed by the present invention; Figure 6 A schematic diagram of the structure of a mounting base for a precision mold surface milling device proposed by the present invention; Figure 7 A schematic diagram of the structure of a slider and a pressing plate of a precision mold surface milling device proposed by the present invention; Figure 8 A schematic structural diagram of a bracket of a precision mold surface milling device proposed by the present invention; Figure 9 A schematic structural diagram of a differential transmission device for a precision mold surface milling device proposed by the present invention; Figure 10 This is a cross-sectional view of the internal structure of a differential transmission device of a precision mold surface milling device proposed by the present invention.

[0016] In the figure: 1 milling machine, 11 bed, 12 base, 13 lifting table, 14 workbench, 15 crossbeam, 16 spindle, 2 tool holder, 21 tool shaft, 211 connecting flange, 212 fixing plate, 213 connecting member, 2131 gear, 2132 threaded shaft, 214 first driving wheel, 215 blade, 22 mounting seat, 221 threaded groove, 222 mounting groove, 223 sliding groove, 224 slider, 225 pressing plate, 226 threaded rod, 23 support, 231 mounting plate, 232 first limiting plate, 2321 first rotating shaft, 2322 second driving wheel, 2323 first transmission belt, 233 support rod, 234 second limiting plate, 2341 second rotating shaft, 235 driving pulley, 2351 first fixed cone disc, 2352 first moving cone disc, 236 driven pulley, 2361 second fixed cone disc, 2362 second moving cone disc, 237 second transmission belt. Specific implementation mode

[0017] Refer to Figures 1-10 , a precision mold surface milling device, including a milling machine 1, the milling machine 1 includes a bed 11, a base 12 is fixedly installed below the bed 11, a workbench 14 is installed on the base 12 through a lifting table 13, a crossbeam 15 is installed on the bed 11, and a spindle 16 is installed on the crossbeam 15. A tool holder 2 is fixedly installed below the spindle 16 through a connecting component. The tool holder 2 includes a tool shaft 21. A fixing plate 212 is fixedly installed at the bottom end of the tool shaft 21. A plurality of symmetric connecting members 213 are rotationally connected in a limited manner on the fixing plate 212. A clamping groove is formed in the fixing plate 212, and the connecting members 213 are rotationally connected in a limited manner in the clamping groove. An installation seat 22 is installed between the plurality of connecting members 213. A tool fastening component is installed on the installation seat 22. A gear 2131 is fixedly installed at the top end of the connecting member 213. A first driving wheel 214 is rotationally connected in a limited manner on the tool shaft 21. A tooth groove meshed with the gear 2131 is formed in the bottom end of the first driving wheel 214. A threaded shaft 2132 is fixedly installed at the bottom end of the connecting member 213. A plurality of threaded grooves 221 threadedly connected with the threaded shaft 2132 are formed in the installation seat 22. A differential transmission device for driving the first driving wheel 214 to rotate is fixedly installed on one side surface of the crossbeam 15.

[0018] During the process of milling the surface of a precision mold using the end milling method, as the end milling progresses, affected by the wear caused by friction, the length of the milling cutter gradually decreases, and the height of the bottom surface of the cutting edge at the bottom of the milling cutter for milling gradually rises, thus affecting the quality and accuracy of the milling process on the surface of the precision mold. In order to reduce the impact of the wear of the milling cutter on the quality and accuracy of the milling process, it is necessary to actively compensate for the height change of the bottom side end face of the milling cutter. Generally, the installation height of the tool on the milling machine is fixed, and this compensation needs to be completed by driving the workpiece with a lifting table. Also, because the wear rate of the milling cutter is positively correlated with the rotational speed of the milling cutter, actively compensating through the lifting table will increase the control difficulty of the lifting table and there will be a large error. To solve the above problems, the present invention provides a differential transmission device in the tool holder 2. By means of the differential transmission device, the first transmission wheel 214 is driven to rotate in the same direction as the tool shaft 21. Since it is a differential transmission, there will be a rotational speed difference between the angular velocity of the rotation of the first transmission wheel 214 and the angular velocity of the rotation of the tool shaft 21. Affected by this rotational speed difference, there will be relative rotation between the fixed disk 212 fixedly installed at the bottom end of the tool shaft 21 and the first transmission wheel 214. Under the action of the relative rotation, the first transmission wheel 214 will drive the gear 2131 meshed with it to rotate around the center of the connecting member 213, and then drive the connecting member 213 and the threaded shaft 2132 to also rotate around the center of the connecting member 213. Combining the threaded connection between the threaded shaft 2132 and the threaded groove 221 on the mounting seat 22, the mounting seat 22 is driven to move downward actively to automatically and actively compensate for the height change of the bottom side end face of the milling cutter. Since the rotational speed difference is positively correlated with the rotational speed of the tool shaft 21, that is, the rotational speed of the milling cutter, the active compensation used in the present invention has the advantages of low control difficulty and small error compared with the active compensation realized by driving the workpiece with a lifting table.

[0019] Such as Figure 2 、 Figure 9 And Figure 10As shown in the figure, the differential transmission device includes a bracket 23. One end of the bracket 23 is fixedly installed with a mounting plate 231. The mounting plate 231 is fixedly installed on one side surface of the cross beam 15 through screws. A first limiting plate 232 is fixedly installed below the bracket 23. A support rod 233 is fixedly installed on the first limiting plate 232. A second limiting plate 234 is fixedly installed on the support rod 233. A first rotating shaft 2321 is rotationally connected in the first limiting plate 232 in a limited manner. A second rotating shaft 2341 is rotationally connected in the second limiting plate 234 in a limited manner. A second transmission wheel 2322 is fixedly connected to the first rotating shaft 2321. The second transmission wheel 2322 is drivingly connected to the first transmission wheel 214 through a first transmission belt 2323 and the angular velocities of the second transmission wheel 2322 and the first transmission wheel 214 are the same when they rotate. A driving pulley 235 is fixedly installed between the first rotating shaft 2321 and the second rotating shaft 2341. A driven pulley 236 is fixedly installed on the tool shaft 21. The driving pulley 235 is drivingly connected to the driven pulley 236 through a second transmission belt 237 and the angular velocities of the driving pulley 235 and the driven pulley 236 are different when they rotate.

[0020] After the main shaft 16 is started, the main shaft 16 drives the tool holder 2 fixedly connected to it through the connecting component to rotate. The tool shaft 21 rotates together with the tool holder 2. The tool shaft 21 drives the driven pulley 236 fixedly connected to it to rotate. The driven pulley 236 drives the driving pulley 235 to rotate through the second transmission belt 237. The driving pulley 235 drives the first rotating shaft 2321 fixedly connected to it to rotate. The first rotating shaft 2321 then drives the first transmission wheel 214 to rotate through the second transmission wheel 2322 and the first transmission belt 2323. Since the angular velocities of the driving pulley 235 and the driven pulley 236 are different when they rotate, while the angular velocities of the second transmission wheel 2322 and the first transmission wheel 214 are the same when they rotate, after the transmission of the differential transmission device, the first transmission wheel 214 will rotate in the same direction as the tool shaft 21 but with different angular velocities, thus there is a speed difference.

[0021] As Figure 9 and Figure 10As shown, the support rod 233 is a hydraulic cylinder. The driving pulley 235 is jointly composed of a first fixed cone disk 2351 and a first moving cone disk 2352. The driven pulley 236 is jointly composed of a second fixed cone disk 2361 and a second moving cone disk 2362. The second transmission belt 237 is a metal transmission belt. The first fixed cone disk 2351 is fixedly connected to the first rotating shaft 2321. The first moving cone disk 2352 is fixedly connected to the second rotating shaft 2341. A limiting groove is formed in the first fixed cone disk 2351. The bottom end of the second rotating shaft 2341 is connected to the limiting groove in a limiting sliding manner. The middle part of the tool shaft 21 is a square rod. The second fixed cone disk 2361 is fixedly connected to the square rod. The second moving cone disk 2362 is connected to the square rod in a limiting sliding manner. A spring is fixedly connected between the second fixed cone disk 2361 and the second moving cone disk 2362. The first fixed cone disk 2351, the first moving cone disk 2352, the second fixed cone disk 2361, the second moving cone disk 2362 and the second transmission belt 237 together constitute an adjustable transmission structure.

[0022] An adjustable transmission structure is formed by the first fixed cone disk 2351, the first movable cone disk 2352, the second fixed cone disk 2361, the second movable cone disk 2362 and the second transmission belt 237. By controlling the length of the support rod 233, the distance between the first fixed cone disk 2351 and the first movable cone disk 2352 can be controlled and adjusted, and then the meshing positions of the second transmission belt 237 with the first fixed cone disk 2351 and the first movable cone disk 2352 can be adjusted. When the meshing positions of the second transmission belt 237 with the first fixed cone disk 2351 and the first movable cone disk 2352 change, affected by the elastic force of the spring, the distance between the second fixed cone disk 2361 and the second movable cone disk 2362 will also change adaptively, and then the meshing positions of the second transmission belt 237 with the second fixed cone disk 2361 and the second movable cone disk 2362 will be changed, so that the transmission ratio between the driving pulley 235 and the driven pulley 236 changes (specifically, the principle of continuously variable transmission can be referred to). Therefore, the transmission ratio of the differential transmission device can be controlled and changed by the support rod 233, and the angular velocity difference between the rotation of the cutter shaft 21 and the first transmission wheel 214 can be controlled and changed, so as to control and change the progress of active compensation. The advantage of this effect is that for precision die workpieces of different materials, the wear rates of milling cutter tools are also different. With the help of this adjustable transmission structure, the progress of active compensation can be adjusted accordingly according to the different materials of precision die workpieces, so that the present invention can be applied to the active compensation of milling cutter wear during the end milling process of precision dies of different materials. In addition, when the spindle 16 drives the cutter shaft 21 to rotate but the end milling process of the precision die workpiece has not started, under the action of the differential transmission device, active compensation will still be carried out, but active compensation is not required during non-end milling, so there will be errors caused by redundant compensation. Since the idle running time of the milling cutter is very short compared with the milling time, the error is very small. In order to further reduce this error and improve the quality and accuracy of the surface machining of precision dies, the adjustable transmission structure can be used to adjust the differential transmission device to the corresponding differential transmission state, that is, the active compensation state, only during the milling process, and the differential transmission device is adjusted to the synchronous state where the angular velocities of the cutter shaft 21 and the first transmission wheel 214 are the same at other times. No active compensation is carried out in this state.

[0023] As Figure 3 and Figure 4 shown, a plurality of rotationally symmetric blades 215 are fixedly installed on the bottom surface of the first transmission wheel 214, and a plurality of symmetric empty slots are formed on the fixed disk 212. When the first transmission wheel 214 rotates, the first transmission wheel 214 drives a plurality of blades 215 to rotate, and cooperate with the empty slots on the fixed disk 212 to generate an air flow that quickly passes through the empty slots and blows towards the mounting seat 22, which helps to improve the heat dissipation efficiency of the milling cutter tool during the milling process.

[0024] As Figure 1 andFigure 3 As shown, the connecting component includes two connecting flange plates 211 respectively and fixedly connected to the bottom end of the main shaft 16 and the top end of the tool shaft 21. The two connecting flange plates 211 are fixedly connected by a plurality of bolt nuts. A positioning post is fixedly installed on one of the connecting flange plates 211, and a positioning groove matching the guiding post is formed on the other connecting flange plate 211. With the guiding action of the positioning post and the positioning groove, when fixedly installing between the main shaft 16 and the tool shaft 21, the quick alignment between the two connecting flange plates 211 can be completed, reducing the installation difficulty and improving the installation efficiency.

[0025] As Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown in, the tool fastening component includes a plurality of rotationally symmetric installation grooves 222 formed in the mounting base 22. A sliding groove 223 is formed on one side surface of each of the plurality of installation grooves 222. A slider 224 is slidably connected in a limited manner in the sliding groove 223. A pressing plate 225 slidably connected in the installation groove 222 is fixedly connected to the slider 224. A threaded rod 226 threadedly connected to the slider 224 is rotatably connected in a limited manner on one inner side surface of the sliding groove 223.

[0026] When installing the milling cutter tool, first place the tool into the installation groove 222, and then use an automatic screw tightening tool to rotate the threaded rod 226. Through the thread action, the slider 224 is driven to move towards the inner side of the sliding groove 223, driving the pressing plate 225 to cooperate with the inner side wall of the installation groove 222 to squeeze and press the tool, thereby completing the fixed installation of the milling cutter tool.

[0027] As Figure 8 As shown, the bracket 23 is L-shaped. Reinforcing plates are fixedly installed at the connection between the bracket 23 and the first limiting plate 232 and at its own right angle to enhance the structural stability.

[0028] A milling method for a precision mold surface milling device includes the following steps: S1. When performing surface milling on a precision mold, first install the precision mold workpiece on the workbench 14, then place the tool into the installation groove 222, use an automatic screw tightening tool to rotate the threaded rod 226, drive the slider 224 to move towards the inner side of the sliding groove 223 through the thread action, drive the pressing plate 225 to cooperate with the inner side wall of the installation groove 222 to squeeze and press the tool, and complete the fixed installation of the milling cutter tool; S2. Immediately afterwards, start the main shaft 16. The main shaft 16 drives the tool holder 2 fixedly connected thereto through the connecting component to rotate. The tool shaft 21 rotates together with the tool holder 2. The tool shaft 21 drives the mounting base 22 to rotate together through the fixed disk 212 and the connecting piece 213, driving the milling cutter to rotate. Then, control the lifting table 13 to drive the workbench 14 and the precision mold workpiece mounted on the workbench 14 to move, providing a feed motion, and use the rotating milling cutter to perform end milling on the surface of the precision mold workpiece; S3. When performing end milling, the tool shaft 21 drives the driven pulley 236 fixedly connected thereto to rotate. The driven pulley 236 drives the driving pulley 235 to rotate by means of the second transmission belt 237. The driving pulley 235 drives the first rotating shaft 2321 fixedly connected thereto to rotate. The first rotating shaft 2321 then drives the first transmission wheel 214 to rotate through the second transmission wheel 2322 and the first transmission belt 2323. By starting and controlling the length of the support rod 233, control and adjust the distance between the first fixed cone disk 2351 and the first moving cone disk 2352, and further adjust the meshing position of the second transmission belt 237 with the first fixed cone disk 2351 and the first moving cone disk 2352. When the meshing position of the second transmission belt 237 with the first fixed cone disk 2351 and the first moving cone disk 2352 changes, affected by the elastic force of the spring, the distance between the second fixed cone disk 2361 and the second moving cone disk 2362 will also change adaptively, and further change the meshing position of the second transmission belt 237 with the second fixed cone disk 2361 and the second moving cone disk 2362, so that the transmission ratio between the driving pulley 235 and the driven pulley 236 changes. By controlling and changing the angular velocity difference between the rotation of the tool shaft 21 and the first transmission wheel 214, there will be relative rotation between the fixed disk 212 and the first transmission wheel 214. Under the action of the relative rotation, the first transmission wheel 214 will drive the gear 2131 meshed with it to rotate around the center of the connecting piece 213, and further drive the connecting piece 213 and the threaded shaft 2132 to also rotate around the center of the connecting piece 213. Combining the threaded connection between the threaded shaft 2132 and the threaded groove 221 on the mounting base 22, drive the mounting base 22 to move downward actively to automatically and actively compensate for the height change of the bottom end face of the milling cutter; S4. When the milling cutter is not in the end milling state, by starting and controlling the length of the support rod 233, change the transmission ratio between the driving pulley 235 and the driven pulley 236, so that the angular velocities of the two are the same, and further make the angular velocities of the tool shaft 21 and the first transmission wheel 214 the same. At this time, no active compensation is performed.

[0029] In the present invention, when performing surface milling on a precision mold, first install the precision mold workpiece on the workbench 14, then place the tool into the mounting groove 222, and use an automatic screwdriver tool to rotate the threaded rod 226. Through the thread action, drive the slider 224 to move towards the inner side of the chute 223, driving the pressing plate 225 to cooperate with the inner wall of the mounting groove 222 to squeeze and press the tool, completing the fixed installation of the milling cutter tool; Immediately afterwards, start the main shaft 16. The main shaft 16 drives the tool holder 2 fixedly connected to it through the connecting component to rotate. The tool shaft 21 rotates together with the tool holder 2. The tool shaft 21 drives the mounting seat 22 to rotate together through the fixed disk 212 and the connecting piece 213, driving the milling cutter to rotate. Then control the lifting table 13 to drive the workbench 14 and the precision mold workpiece installed on the workbench 14 to move, providing a feed motion, and use the rotating milling cutter to perform end milling on the surface of the precision mold workpiece; During end milling, the tool shaft 21 drives the driven pulley 236 fixedly connected to it to rotate. The driven pulley 236 drives the driving pulley 235 to rotate by means of the second transmission belt 237. The driving pulley 235 drives the first rotating shaft 2321 fixedly connected to it to rotate. The first rotating shaft 2321 then drives the first transmission wheel 214 to rotate through the second transmission wheel 2322 and the first transmission belt 2323. By starting and controlling the length of the support rod 233, control and adjust the distance between the first fixed cone disk 2351 and the first moving cone disk 2352, and further adjust the meshing position of the second transmission belt 237 with the first fixed cone disk 2351 and the first moving cone disk 2352. When the meshing position of the second transmission belt 237 with the first fixed cone disk 2351 and the first moving cone disk 2352 changes, affected by the elastic force of the spring, the distance between the second fixed cone disk 2361 and the second moving cone disk 2362 will also change adaptively, thereby changing the meshing position of the second transmission belt 237 with the second fixed cone disk 2361 and the second moving cone disk 2362, so that the transmission ratio between the driving pulley 235 and the driven pulley 236 changes. By controlling and changing the angular velocity difference between the rotation of the tool shaft 21 and the first transmission wheel 214, there will be relative rotation between the fixed disk 212 and the first transmission wheel 214. Under the action of the relative rotation, the first transmission wheel 214 will drive the gear 2131 meshingly connected to it to rotate around the center of the connecting piece 213, thereby driving the connecting piece 213 and the threaded shaft 2132 to also rotate around the center of the connecting piece 213. Combining the threaded connection between the threaded shaft 2132 and the threaded groove 221 on the mounting seat 22, drive the mounting seat 22 to actively move downward to automatically and actively compensate for the height change of the bottom end face of the milling cutter; When the milling cutter is not in the face milling machining state, by starting and controlling the length of the support rod 233, the transmission ratio between the driving pulley 235 and the driven pulley 236 is changed so that their angular velocities of rotation are the same, and further the angular velocity of the tool shaft 21 is the same as that of the first transmission wheel 214. At this time, active compensation is not performed.

Claims

1. A precision mold surface milling device, including a milling machine (1), characterized in that, The milling machine (1) comprises a bed (11), a base (12) is fixedly mounted below the bed (11), a workbench (14) is mounted on the base (12) via a lifting platform (13), a crossbeam (15) is mounted on the bed (11), a spindle (16) is mounted on the crossbeam (15), a tool seat (2) is fixedly mounted below the spindle (16) via a connecting assembly, the tool seat (2) comprises a tool shaft (21), a fixed plate (212) is fixedly mounted on the bottom end of the tool shaft (21), the fixed plate (212) is rotatably connected to an upper limit position with a plurality of symmetrical connecting members (213), and mounting brackets are mounted between the plurality of connecting members (213). A mounting seat (22) is provided on the mounting seat (22), a tool fastening assembly is provided on the mounting seat (22), a gear (2131) is fixedly provided on the top end of the connecting member (213), the upper limit position of the knife shaft (21) is rotatably connected to a first transmission wheel (214), a tooth groove meshingly connected to the gear (2131) is provided in the bottom end of the first transmission wheel (214), a threaded shaft (2132) is fixedly provided on the bottom end of the connecting member (213), a plurality of threaded grooves (221) threadedly connected to the threaded shaft (2132) are provided in the mounting seat (22), and a differential transmission device for driving the first transmission wheel (214) to rotate is fixedly provided on a side surface of the crossbeam (15).

2. The surface milling equipment for precision molds according to claim 1, characterized in that, The differential transmission device comprises a bracket (23), a mounting plate (231) is fixedly mounted on one end of the bracket (23), the mounting plate (231) is fixedly mounted on a side surface of the crossbeam (15) by means of screws, a first limit plate (232) is fixedly mounted below the bracket (23), a support rod (233) is fixedly mounted on the first limit plate (232), a second limit plate (234) is fixedly mounted on the support rod (233), a first rotation shaft (2321) is rotationally connected to the first limit plate (232), a second rotation shaft (2341) is rotationally connected to the second limit plate (234), and the first rotation shaft (232) is rotationally connected to the first limit plate (232). 1), a second transmission wheel (2322) is fixedly connected to the first transmission wheel (214), the second transmission wheel (2322) is connected to the first transmission wheel (214) through a first transmission belt (2323), and the second transmission wheel (2322) and the first transmission wheel (214) rotate at the same angular velocity, a driving pulley (235) is fixedly installed between the first rotating shaft (2321) and the second rotating shaft (2341), a driven pulley (236) is fixedly installed on the knife shaft (21), the driving pulley (235) and the driven pulley (236) are connected to each other through a second transmission belt (237), and the driving pulley (235) and the driven pulley (236) rotate at different angular velocities.

3. A precision mold surface milling device according to claim 2, characterized in that, The support rod (233) is a hydraulic cylinder. The driving pulley (235) is composed of a first fixed cone disk (2351) and a first moving cone disk (2352). The driven pulley (236) is composed of a second fixed cone disk (2361) and a second moving cone disk (2362). The second transmission belt (237) is a metal transmission belt. The first fixed cone disk (2351) is fixedly connected to the first rotating shaft (2321). The first moving cone disk (2352) is fixedly connected to the second rotating shaft (2341). A limiting groove is formed in the first fixed cone disk (2351). The bottom end of the second rotating shaft (2341) is connected to the limiting groove in a limiting sliding manner. The middle part of the cutter shaft (21) is a square rod. The second fixed cone disk (2361) is fixedly connected to the square rod. The second moving cone disk (2362) is connected to the square rod in a limiting sliding manner. A spring is fixedly connected between the second fixed cone disk (2361) and the second moving cone disk (2362). The first fixed cone disk (2351), the first moving cone disk (2352), the second fixed cone disk (2361), the second moving cone disk (2362) and the second transmission belt (237) together constitute an adjustable transmission structure.

4. A precision mold surface milling device according to claim 3, characterized in that, A plurality of rotationally symmetric blades (215) are fixedly installed on the bottom surface of the first transmission wheel (214). A plurality of symmetric empty grooves are formed in the fixed disk (212).

5. A precision mold surface milling device according to claim 4, characterized in that, The connecting assembly includes two connecting flange plates (211) respectively fixedly connected to the bottom end of the main shaft (16) and the top end of the cutter shaft (21). The two connecting flange plates (211) are fixedly connected by a plurality of bolts and nuts. A positioning column is fixedly installed on one of the connecting flange plates (211), and a positioning groove matching the guiding column is formed on the other connecting flange plate (211).

6. The surface milling equipment for precision molds according to claim 5, wherein The tool fastening assembly includes a plurality of rotationally symmetric mounting grooves (222) formed in the mounting seat (22). A sliding groove (223) is formed on one side surface of each of the plurality of mounting grooves (222). A slider (224) is connected to the sliding groove (223) in a limiting sliding manner. A pressing plate (225) slidably connected in the mounting groove (222) is fixedly connected to the slider (224). A threaded rod (226) threadedly connected to the slider (224) is rotatably connected to one inner side surface of the sliding groove (223) in a limiting manner.

7. The surface milling equipment for precision molds according to claim 6, characterized in that, The bracket (23) is L-shaped. Reinforcing plates are fixedly installed at the connection between the bracket (23) and the first limiting plate (232) and at its right angle.

8. A milling method for a precision mold surface milling device according to claim 7, characterized in that, Including the following steps: S1. When performing surface milling on a precision mold, first install the precision mold workpiece on the workbench (14), then place the tool in the mounting groove (222), and use an automatic screwdriver tool to rotate the threaded rod (226). Through the thread action, the slider (224) is driven to move towards the inner side of the sliding groove (223), driving the pressing plate (225) to cooperate with the inner side wall of the mounting groove (222) to squeeze and press the tool, completing the fixed installation of the milling cutter tool. S2. Immediately afterwards, start the main shaft (16). The main shaft (16) drives the tool holder (2) fixedly connected thereto through the connecting component to rotate. The tool shaft (21) rotates together with the tool holder (2). The tool shaft (21) drives the mounting seat (22) to rotate together through the fixed disk (212) and the connecting piece (213), driving the milling cutter to rotate. Then, control the lifting table (13) to drive the workbench (14) and the precision mold workpiece mounted on the workbench (14) to move, providing a feeding motion, and use the rotating milling cutter to perform end milling on the surface of the precision mold workpiece; S3. When performing end milling, the tool shaft (21) drives the driven pulley (236) fixedly connected thereto to rotate. The driven pulley (236) drives the driving pulley (235) to rotate by means of the second transmission belt (237). The driving pulley (235) drives the first rotating shaft (2321) fixedly connected thereto to rotate. The first rotating shaft (2321) then drives the first transmission wheel (214) to rotate through the second transmission wheel (2322) and the first transmission belt (2323). By starting and controlling the length of the support rod (233), control and adjust the distance between the first fixed cone disk (2351) and the first movable cone disk (2352), and further adjust the meshing position of the second transmission belt (237) with the first fixed cone disk (2351) and the first movable cone disk (2352). When the meshing position of the second transmission belt (237) with the first fixed cone disk (2351) and the first movable cone disk (2352) changes, affected by the elastic force of the spring, the distance between the second fixed cone disk (2361) and the second movable cone disk (2362) will also change adaptively, and further change the meshing position of the second transmission belt (237) with the second fixed cone disk (2361) and the second movable cone disk (2362), so that the transmission ratio between the driving pulley (235) and the driven pulley (236) changes. By controlling and changing the angular velocity difference between the tool shaft (21) and the first transmission wheel (214), there will be relative rotation between the fixed disk (212) and the first transmission wheel (214). Under the action of the relative rotation, the first transmission wheel (214) will drive the gear (2131) meshed with it to rotate around the center of the connecting piece (213), and further drive the connecting piece (213) and the threaded shaft (2132) to also rotate around the center of the connecting piece (213). Combining the threaded connection between the threaded shaft (2132) and the threaded groove (221) on the mounting seat (22), drive the mounting seat (22) to move downward actively to automatically perform active compensation for the height change of the bottom end face of the milling cutter; S4. When the milling cutter is not in the end milling state, by starting and controlling the length of the support rod (233), change the transmission ratio between the driving pulley (235) and the driven pulley (236), so that the angular velocities of the two are the same, and further make the angular velocities of the tool shaft (21) and the first transmission wheel (214) the same. At this time, no active compensation is performed.

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