A high-precision double-end milling machine special for valve

Abstract

This invention discloses a high-precision double-head milling machine for valves, belonging to the technical field of milling equipment. It includes a frame with a slidable worktable. Spindle boxes are located on both sides of the worktable on the frame. Each spindle box contains a compensation assembly, and a spindle passes through each spindle box. Milling cutter discs are fixedly connected to the ends of each spindle, and the two milling cutter discs are arranged opposite each other. The compensation assembly includes a spare bearing sleeved on the outside of the spindle, with a protrusion on its outer ring. A flexible heat-conducting cable connects the protrusion to the spindle box. Two symmetrically sliding clamping blocks are located on both sides of the spare bearing within the spindle box. An eddy current displacement sensor facing the spindle is also located within the spindle box. This invention avoids downtime and reduced efficiency while ensuring the parallelism of the flange faces at both ends of the valve, preventing impact on assembly accuracy and sealing performance, and meeting the high-precision milling requirements of the valve flanges.

Description

Technical Field

[0001] This invention relates to the field of milling equipment technology, and more specifically, to a high-precision double-head milling machine for valves. Background Technology

[0002] In the valve manufacturing process, the flange faces at both ends of the valve need to be milled using a double-head milling machine. Typically, a double-head milling machine is used to clamp the valve once and mill both ends of the flange face simultaneously. The valve is placed on a worktable, and spindles are installed in the spindle boxes on both sides of the worktable. Bearings are fitted on the outside of the spindles, and milling cutter heads are fixedly connected to the ends of the spindles. The two milling cutter heads mill the flange faces at both ends of the valve simultaneously, thereby completing the high-precision milling of the flange faces at both ends of the valve.

[0003] However, when milling the flange faces at both ends of a valve using the existing double-head milling machine, the milling cutter generates milling resistance. The bearing on the side of the spindle closest to the milling cutter bears the radial component of this milling resistance, and this radial component changes periodically with the milling process. This causes the bearing sleeved on the spindle corresponding to the milling cutter to gradually experience extrusion wear under long-term alternating loads. Consequently, the radial runout of the milling cutter connected to the spindle increases during the milling process of the flange faces at both ends of the valve, resulting in a decrease in the milled flatness of the valve flange faces and an increase in the surface roughness value. This, in turn, affects the assembly accuracy and sealing performance of the flange faces at both ends of the valve, making it difficult to meet the high-precision milling requirements of the flange faces at both ends of the valve.

[0004] In view of this, we propose a high-precision double-head milling machine specifically for valves. Summary of the Invention

[0005] Technical problem to be solved: The purpose of this invention is to provide a high-precision double-head milling machine for valves, which solves the technical problems mentioned in the background art.

[0006] Technical solution: The technical solution of the present invention provides a high-precision double-head milling machine for valves, including a frame, a worktable slidably mounted on the frame, a spindle box mounted on both sides of the worktable, a compensation component in each of the two spindle boxes, a spindle passing through each of the two spindle boxes, and a milling cutter head fixedly connected to the ends of each of the two spindles, with the two milling cutter heads arranged opposite to each other; The compensation assembly includes a spare bearing sleeved on the outside of the spindle. The outer ring of the spare bearing has a protrusion. A flexible heat conductor is connected between the protrusion and the spindle housing. Two symmetrically sliding clamping blocks are provided on both sides of the spare bearing inside the spindle housing. An eddy current displacement sensor facing the spindle is provided inside the spindle housing to monitor the radial runout of the spindle. When the monitored value of the eddy current displacement sensor reaches the first preset threshold, the two clamping blocks advance the first preset distance. One of the clamping blocks first contacts the protrusion at the end facing the protrusion and pushes the protrusion to drive the outer ring of the spare bearing to rotate, causing the flexible heat conductor to relax. Then the two clamping blocks close to clamp the outer ring of the spare bearing and issue a reminder signal.

[0007] As an optional solution of the present invention, the frame is provided with sliding blocks on both sides of the worktable, and the two spindle boxes are respectively fixed on the two sliding blocks.

[0008] As an optional solution of the technical solution of the present invention, when the monitoring value of the eddy current displacement sensor reaches the first preset threshold, the two slides simultaneously drive their respective spindle boxes to actively retract away from the worktable.

[0009] As an optional solution of the technical solution of the present invention, two hydraulic push rods are fixed on the spindle box, and the telescopic ends of the two hydraulic push rods are respectively fixedly connected to two clamping blocks.

[0010] As an optional solution of the present invention, the clamping surface of the clamping block is an arc surface that fits against the outer ring of the spare bearing.

[0011] As an optional solution of the present invention, when the flexible conductive tape is in a straightened state, the end height of the clamping block corresponds to the protrusion.

[0012] As an optional solution of the present invention, a first bearing and a second bearing are sleeved on the outer side of the main shaft. The outer rings of the first bearing and the second bearing are both fixed inside the main shaft box. The first bearing is located on the main shaft near the milling cutter head, and the second bearing is located on the main shaft away from the milling cutter head.

[0013] As an optional solution of the present invention, the spare bearing is located between the first bearing and the second bearing, close to the first bearing.

[0014] As an optional solution of the present invention, when the monitoring value of the eddy current displacement sensor is still higher than the second preset threshold after the two clamping blocks are closed and clamped, the clamping blocks continue to advance the second preset distance.

[0015] As an optional solution of the technical solution of the present invention, when the monitoring value of the eddy current displacement sensor is still higher than the second preset threshold after the clamping block has advanced a second preset distance, both main shafts stop rotating and are shut down for maintenance.

[0016] Beneficial effects: One or more technical solutions provided in this invention have at least the following technical effects or advantages: 1. In this invention, when the eddy current displacement sensor detects that the radial runout of the spindle reaches the first preset threshold, it indicates that the first bearing on the side of the spindle near the milling cutter has been worn by compression, causing the spindle to deviate beyond a certain degree. At this time, the two clamping blocks are driven to advance and close, clamping the outer ring of the spare bearing, so that the spare bearing takes over the positioning and support function of the first bearing, so that the current processing is not interrupted and the workpiece does not need to be re-clamped. This ensures that the processing datum of the flange end faces at both ends of the valve remains unchanged, thereby avoiding the reduction of efficiency due to mid-process stoppage, while ensuring the parallelism of the flange end faces at both ends of the valve. It also avoids the decrease in milling flatness and increase in surface roughness value of the flange end faces at both ends of the valve due to spindle deviation, which would affect the assembly accuracy and sealing performance, thus meeting the high-precision milling processing requirements of the flange end faces at both ends of the valve.

[0017] 2. After the two clamping blocks close and clamp, the eddy current displacement sensor continues to monitor the radial runout of the spindle. Since the spare bearing already generates frictional heat before taking over the positioning support function of the first bearing, and the load increases after taking over the positioning support function of the first bearing, the ball friction intensifies. Heat is conducted to the outer ring of the spare bearing, causing the temperature of the outer ring of the spare bearing to rise. This causes the outer ring of the spare bearing to expand radially and squeeze the clamping surface of the clamping block, increasing the contact pressure and accelerating the extrusion wear between the clamping block and the outer ring of the spare bearing. After the wear accumulates to a certain extent, a gap will appear between the clamping block and the outer ring of the spare bearing. If the monitored value is still higher than the second preset threshold, the clamping block is driven to continue to advance the second preset distance, so that the clamping block re-fits the outer ring of the spare bearing, realizing the repositioning of the spindle. This prevents the spindle from shaking in the gap and accelerating the damage of the spare bearing, ensuring that the spare bearing can continuously and stably position and support the spindle, meeting the high-precision milling requirements of the flanges at both ends of the valve.

[0018] 3. After the clamping block advances the second preset distance, if the monitored value is still higher than the second preset threshold, it is necessary to control both spindles to stop rotating and stop the machine for maintenance to avoid continued clamping causing crushing of the spare bearing outer ring or damage to the spindle. This ensures the completion of the current processing while guaranteeing equipment safety and further meets the high-precision milling requirements of the flanges at both ends of the valve.

[0019] 4. When the spare bearing is not assuming the positioning and support function of the first bearing, the flexible heat-conducting tape holds the outer ring of the spare bearing in place, preventing it from rotating with the spindle. The two clamping blocks hold the stationary outer ring of the spare bearing smoothly, avoiding impact damage when the clamping blocks clamp the high-speed rotating outer ring of the spare bearing. Furthermore, as the clamping blocks advance, one end of the clamping block first contacts the protrusion, pushing the protrusion to rotate the outer ring of the spare bearing, causing the flexible heat-conducting tape to loosen. This prevents the spindle radial runout, which may still exist after the spare bearing assumes the positioning and support function of the first bearing, from periodically stretching the taut flexible heat-conducting tape and causing it to break. Simultaneously, the heat generated by the spare bearing during processing is conducted through the protrusion to the flexible heat-conducting tape, and then from the flexible heat-conducting tape to the spindle box for heat dissipation. This reduces the radial expansion of the spare bearing due to temperature rise, thereby reducing the contact stress between the outer wall of the spare bearing's outer ring and the clamping surface of the clamping blocks, mitigating the squeezing wear between the clamping blocks and the outer ring of the spare bearing, reducing the degree of gap between the clamping blocks and the outer ring of the spare bearing, ensuring the reliable operation and repeated use of the compensation component, and continuously maintaining the high-precision milling of the flanges at both ends of the valve.

[0020] 5. Slide seats are slidably installed on both sides of the worktable on the frame. Two spindle boxes are fixed on the two slide seats respectively. When the monitoring value of the eddy current displacement sensor reaches the first preset threshold, the two slide seats simultaneously drive their respective spindle boxes to actively retract away from the worktable. This causes the milling cutter head, which has radially runout due to the extrusion and wear of the first bearing, to actively disengage from the flange end face of the valve. This not only helps to reduce the resistance encountered when the two clamping blocks close and clamp the spare bearing, making it easier to quickly reposition the runout spindle, but also avoids secondary damage to the valve flange end face by the milling cutter head during the repositioning process of the spindle. This effectively improves the machining accuracy of the flange end faces at both ends of the valve, thereby meeting the high-precision milling requirements of the flange end faces at both ends of the valve. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0022] Figure 2 This is a first cross-sectional view of a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0023] Figure 3 This is a second cross-sectional view of a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the first three-dimensional structure of the spindle box in a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the second three-dimensional structure of the spindle box in a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of the first cross-sectional structure of the spindle box in a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram of the second cross-sectional structure of the spindle box in a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0028] Figure 8 This is a three-dimensional structural diagram of the spindle in a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0029] Figure 9 This is a schematic diagram of the spindle structure of a high-precision double-head milling machine for valves, as disclosed in a preferred embodiment of the present invention.

[0030] Figure 10 A preferred embodiment of the present invention discloses a high-precision double-head milling machine for valves. Figure 9 A magnified schematic diagram of a portion of the structure in section A.

[0031] Explanation of the labels in the diagram: 1. Frame; 2. Worktable; 3. Slide; 4. Spindle box; 41. Hydraulic push rod; 42. Spindle; 421. First bearing; 422. Second bearing; 43. Eddy current displacement sensor; 44. Spare bearing; 45. Flexible heat conduction tape; 46. Clamping block; 47. Protrusion; 5. Milling cutter head. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Example 1, referring to Figures 1-10 The first embodiment of the present invention provides a high-precision double-head milling machine for valves. This high-precision double-head milling machine for valves includes a frame 1, a worktable 2 slidably mounted on the frame 1, a spindle box 4 mounted on both sides of the worktable 2 on the frame 1, a compensation component in each of the two spindle boxes 4, a spindle 42 passing through each of the two spindle boxes 4, and a milling cutter disc 5 fixedly connected to the end of each of the two spindles 42. The two milling cutter discs 5 are arranged opposite to each other. The compensation assembly includes a spare bearing 44 sleeved on the outside of the spindle 42. The outer ring of the spare bearing 44 is provided with a protrusion 47. A flexible heat conductor 45 is connected between the protrusion 47 and the spindle box 4. Two symmetrically sliding clamping blocks 46 are provided on both sides of the spare bearing 44 inside the spindle box 4. An eddy current displacement sensor 43 facing the spindle 42 is provided inside the spindle box 4 to monitor the radial runout of the spindle 42. When the monitored value of the eddy current displacement sensor 43 reaches the first preset threshold, the two clamping blocks 46 advance the first preset distance. One of the clamping blocks 46 first contacts the protrusion 47 at its end and pushes the protrusion 47 to drive the outer ring of the spare bearing 44 to rotate, causing the flexible conductive tape 45 to loosen. Then the two clamping blocks 46 close to clamp the outer ring of the spare bearing 44 and issue a reminder signal.

[0036] The bump 47 is made of a metal thermally conductive material to facilitate the conduction of heat from the outer ring of the spare bearing 44 to the flexible heat-conducting tape 45.

[0037] The frame 1 has sliding blocks 3 on both sides of the worktable 2, and the two spindle boxes 4 are fixed on the two sliding blocks 3 respectively.

[0038] Two hydraulic push rods 41 are fixed on the spindle box 4, and the telescopic ends of the two hydraulic push rods 41 are respectively fixedly connected to two clamping blocks 46.

[0039] The clamping surface of the clamping block 46 is an arc surface that fits against the outer ring of the spare bearing 44.

[0040] When the flexible conductive tape 45 is in a straightened state, the end height of the clamping block 46 corresponds to that of the protrusion 47.

[0041] A first bearing 421 and a second bearing 422 are sleeved on the outer side of the spindle 42. The outer rings of the first bearing 421 and the second bearing 422 are both fixed inside the spindle box 4. The first bearing 421 is located on the spindle 42 near the milling cutter 5, and the second bearing 422 is located on the spindle 42 away from the milling cutter 5.

[0042] The spare bearing 44 is located between the first bearing 421 and the second bearing 422, close to the first bearing 421.

[0043] The frame 1 is also equipped with a first drive screw for driving the worktable 2 to slide along the frame 1, and a second drive screw for driving the slide block 3 to slide along the frame 1. The first and second drive screws are respectively connected to the main controller. The worktable 2 is used to carry the valve workpiece. The two slide blocks 3 drive the two spindle boxes 4 to move closer to or away from the worktable 2, so that the two milling cutter discs 5 mill the flange end faces at both ends of the valve. The main controller is connected to the drive motors of the eddy current displacement sensor 43, the hydraulic push rod 41, the first drive screw, the second drive screw, and the spindle 42. It is used to receive the monitoring signal of the eddy current displacement sensor 43 and control the movement of the hydraulic push rod 41, the slide block 3, and the spindle 42. The above-mentioned drive screws and main controller are all prior art and will not be described in detail here.

[0044] During operation, the valve workpiece is clamped onto the worktable 2. The main controller controls the two slides 3 to slide along the frame 1, bringing the two spindle boxes 4 closer to the worktable 2. The movement of the worktable 2 causes the milling cutter discs 5 at the ends of the two spindles 42 to perform continuous milling operations on the flange faces at both ends of the valve. At this time, the spindle 42 passes through the spindle box 4 and is positioned and supported by the first bearing 421 and the second bearing 422. The first bearing 421 is located on the spindle 42 near the milling cutter disc 5, bearing the milling action of the milling cutter disc 5 on the valve flange faces. The radial component of the milling resistance generated during the milling process changes periodically with the milling process. The spare bearing 44 is located between the first bearing 421 and the second bearing 422, close to the first bearing 421. During normal machining, it rotates with the spindle 42 but does not bear external loads. One end of the flexible heat conductor 45 is connected to the protrusion 47 and the other end is connected to the spindle box 4. When the spare bearing 44 does not take over the positioning and support function of the first bearing 421, it pulls the outer ring of the spare bearing 44 so that the outer ring of the spare bearing 44 does not rotate with the spindle 42.

[0045] As processing progresses, the first bearing 421 gradually experiences extrusive wear under long-term alternating loads. This leads to increased radial runout of the milling cutter disc 5 connected to the spindle 42 during milling of the flange faces at both ends of the valve. Consequently, the milled flatness of the valve flange faces decreases, and the surface roughness increases. The eddy current displacement sensor 43 monitors the radial runout of the spindle 42 in real time from the start of processing. When the monitored value reaches the first preset threshold, it indicates that the first bearing 421 has significantly deviated but has not yet caused a decrease in the flatness of the flange faces or an increase in the surface roughness. At this time, the main controller controls the two hydraulic push rods 41 to drive the two clamping blocks 46 to advance the first preset distance. Since the flexible conductive cable 45 holds the outer ring of the spare bearing 44 when the spare bearing 44 does not take over the positioning support function from the first bearing 421, the outer ring of the spare bearing 44 remains stationary, and the two clamping blocks 46... Facing the stationary outer ring of the spare bearing 44, the two stationary parts gradually come together, and the clamping process is stable, avoiding impact damage when the clamping block 46 clamps the high-speed rotating outer ring of the spare bearing 44. Thus, when the first bearing 421 on the side of the spindle 42 near the milling cutter 5 is misaligned due to extrusion wear, but before the flatness of the flange end face decreases or the surface roughness increases, the spare bearing 44 takes over the positioning and support function of the first bearing 421, so that the machining is not interrupted and the workpiece does not need to be re-clamped. This ensures that the machining datum of the flange end faces at both ends of the valve remains unchanged, thereby avoiding downtime and reducing efficiency while ensuring the parallelism of the flange end faces at both ends of the valve. It also prevents the assembly accuracy and sealing performance from being affected by the deflection of the spindle 42, which would lead to a decrease in the milling flatness of the flange end faces at both ends of the valve and an increase in the surface roughness. This meets the high-precision milling requirements of the flanges at both ends of the valve.

[0046] During the advancement of the two clamping blocks 46, the end of one clamping block 46 facing the protrusion 47 contacts the protrusion 47 first, pushing the protrusion 47 to rotate the outer ring of the spare bearing 44. Since the flexible conductive tape 45 is in a straightened state, the height of the end of the clamping block 46 corresponds to the protrusion 47. Therefore, the end contacts the protrusion 47 before the arc surface of the clamping block 46, pushing the protrusion 47 to rotate slightly in the direction that relaxes the flexible conductive tape 45, thus relaxing the flexible conductive tape 45. Subsequently, the arc surface of the two clamping blocks 46 fits against the outer ring of the spare bearing 44, and the two clamping blocks 46 close to clamp the outer ring of the spare bearing 44, so that the spare bearing 44 takes over the positioning and support function from the first bearing 421. Thus, the flexible conductive tape 45 is relaxed before clamping to prevent the spare bearing 44 from taking over the position of the first bearing 421. After the main shaft 42 assumes the positioning and support function, its radial runout periodically pulls the taut flexible conductive tape 45, causing it to break. At the same time, the heat generated by the spare bearing 44 during processing is conducted to the flexible conductive tape 45 through the protrusion 47, and then conducted to the main shaft box 4 for heat dissipation. This reduces the radial expansion of the spare bearing 44 due to temperature rise, thereby reducing the contact stress between the outer wall of the spare bearing 44's outer ring and the clamping surface of the clamping block 46, reducing the extrusion wear between the clamping block 46 and the outer ring of the spare bearing 44, reducing the degree of gap between the clamping block 46 and the outer ring of the spare bearing 44, ensuring that the compensation component can be reliably executed and used multiple times, and continuously maintaining the high-precision milling of the flanges at both ends of the valve. At this time, the main controller issues a reminder signal to remind the operator to replace the first bearing 421 after the current processing is completed.

[0047] Since the spare bearing 44 takes over the positioning and support function of the first bearing 421, the first bearing 421 no longer bears the radial component force and will not deteriorate further. The current processing continues. After the processing is completed, the first bearing 421 is replaced according to the reminder signal. During the process of the spare bearing 44 taking over the positioning and support function of the first bearing 421, the worktable 2 does not move, the valve workpiece is not re-clamped, the processing datum of the flanges at both ends remains unchanged, and the parallelism of the flanges at both ends is ensured by the simultaneous processing of the double-head milling machine in one clamping.

[0048] Once the machining is complete, the main controller stops the spindle 42 from rotating according to the reminder signal. The operator can then replace the first bearing 421 without reclamping the valve workpiece, and inspect the spare bearing 44, clamping block 46, and flexible heat conductor 45. Since the spare bearing 44 takes over the positioning and support function from the first bearing 421, the process is completed without the spindle 42 rotating or the workpiece being reclamped. Therefore, the machining datum of the flange end faces at both ends of the valve remains consistent. The parallelism of the flange end faces at both ends is ensured by the simultaneous machining of the double-head milling machine in one clamping. There is no need to perform secondary alignment of the valve workpiece, nor is it necessary to treat the machined end faces as rework pieces due to midway stoppage. This ensures the machining accuracy of the flange end faces at both ends of the valve while improving batch processing efficiency and reducing processing costs.

[0049] Example 2, refer to Figures 1-6 This is the second embodiment of the present invention, which differs from the first embodiment in that: When the monitored value of the eddy current displacement sensor 43 reaches the first preset threshold, the two slides 3 simultaneously drive their respective spindle boxes 4 to actively retract away from the worktable 2.

[0050] During use, when the monitored value of the eddy current displacement sensor 43 reaches the first preset threshold and the main controller triggers the clamping block 46 to advance, the main controller simultaneously controls the two slide blocks 3 to actively retract along the frame 1 away from the worktable 2. This causes the milling cutter disc 5, which has radially runout due to the crushing wear of the first bearing 421, to actively detach from the valve flange end face. This not only helps reduce the resistance encountered when the two clamping blocks 46 close and clamp the spare bearing 44, facilitating the rapid repositioning of the runout spindle 42, but also avoids secondary damage to the valve flange end face caused by the milling cutter disc 5 during the repositioning process of the spindle 42. This effectively improves the machining accuracy of the flange end faces at both ends of the valve, thereby meeting the high-precision milling requirements of the flange end faces at both ends of the valve. At the same time, the active retraction of the spindle 42 on the other side can prevent the milling cutter disc 5 from continuously rubbing at the same position on the valve flange end face, which would cause the workpiece surface to overheat and affect the surface quality of the product. After the above active retraction is completed, the two clamping blocks 46 advance in the above manner, first pushing the protrusion 47, so that the flexible heat conduction cable 45 is relaxed and then closing to clamp the outer ring of the spare bearing 44. After the spare bearing 44 takes over the positioning and support function of the first bearing 421, the two slides 3 drive the spindle box 4 to approach the worktable 2 again to continue to complete this machining.

[0051] The remaining structure is the same as that in Example 1.

[0052] Example 3, referring to Figures 6-10 This is the third embodiment of the present invention, which differs from the second embodiment in that: After the two clamping blocks 46 close and clamp, if the monitored value of the eddy current displacement sensor 43 is still higher than the second preset threshold, the clamping blocks 46 continue to advance the second preset distance.

[0053] After the clamping block 46 has advanced the second preset distance, if the monitoring value of the eddy current displacement sensor 43 is still higher than the second preset threshold, both spindles 42 will stop rotating and the machine will be shut down for maintenance.

[0054] During operation, after the two clamping blocks 46 close and clamp the outer ring of the spare bearing 44, the eddy current displacement sensor 43 continues to monitor the radial runout of the spindle 42. Since the spare bearing 44 already generates frictional heat before assuming the positioning and support function of the first bearing 421, and the load increases after assuming the positioning and support function, the ball friction intensifies. Heat is conducted to the outer ring of the spare bearing 44, causing its temperature to rise. This leads to radial expansion of the outer ring of the spare bearing 44, compressing the clamping surface of the clamping blocks 46, increasing the contact pressure, and accelerating the extrusion wear between the clamping blocks 46 and the outer ring of the spare bearing 44. Once the wear accumulates to a certain extent, the clamping... A gap may appear between the holding block 46 and the outer ring of the spare bearing 44. Even if the holding block 46 is in place at the first preset distance, the spindle 42 may still wobble within the gap, and the radial runout is still too high. At this time, if the monitoring value of the eddy current displacement sensor 43 is still higher than the second preset threshold, the main controller controls the two hydraulic push rods 41 to drive the holding block 46 to continue to advance the second preset distance, so that the holding block 46 re-fits the outer ring of the spare bearing 44, thereby achieving the repositioning of the spindle 42. This prevents the spindle 42 from wobble within the gap and thus accelerates the damage to the spare bearing 44, ensuring that the spare bearing 44 can continuously and stably position and support the spindle 42, meeting the high-precision milling requirements of the flanges at both ends of the valve.

[0055] After the clamping block 46 advances the second preset distance, the eddy current displacement sensor 43 monitors the radial runout of the spindle 42 again. If the monitored value is lower than the second preset threshold, it indicates that the spare bearing 44 has once again assumed the positioning and support function for the spindle 42, and machining continues. After this machining is completed, the first bearing 421 is replaced, and the wear of the spare bearing 44 and the clamping block 46 is checked. If the monitored value is still higher than the second preset threshold, it indicates that the wear has exceeded the limit. Continued clamping may cause the outer ring of the spare bearing 44 to crush or the spindle 42 to be damaged. The main controller controls both spindles 42 to stop rotating and shuts down for maintenance. The first bearing 421, the spare bearing 44, and the clamping block 46 are replaced to avoid continued clamping causing the outer ring of the spare bearing 44 to crush or the spindle 42 to be damaged. This ensures the completion of this machining while ensuring equipment safety and further meets the high-precision milling requirements of the flanges at both ends of the valve. The second preset distance can only be advanced once. If the monitored value is still higher than the second preset threshold after advancing the second preset distance, no further advancement is allowed, and the machine is shut down for maintenance. The one-time limit of the second preset distance itself serves as a criterion for the wear limit.

[0056] The remaining structure is the same as that in Example 2.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision double-head milling machine for valves, characterized in that: The device includes a frame, on which a worktable is slidably mounted. Spindle boxes are mounted on both sides of the worktable. Compensation components are installed in both spindle boxes. Spindles are inserted through both spindle boxes. Milling cutter discs are fixedly connected to the ends of both spindles. The two milling cutter discs are arranged opposite to each other. The compensation assembly includes a spare bearing sleeved on the outside of the spindle. The outer ring of the spare bearing has a protrusion. A flexible heat conductor is connected between the protrusion and the spindle housing. Two symmetrically sliding clamping blocks are provided on both sides of the spare bearing inside the spindle housing. An eddy current displacement sensor facing the spindle is provided inside the spindle housing to monitor the radial runout of the spindle. When the monitored value of the eddy current displacement sensor reaches the first preset threshold, the two clamping blocks advance the first preset distance. One of the clamping blocks first contacts the protrusion at the end facing the protrusion and pushes the protrusion to drive the outer ring of the spare bearing to rotate, causing the flexible heat conductor to relax. Then the two clamping blocks close to clamp the outer ring of the spare bearing and issue a reminder signal.

2. The high-precision double-head milling machine for valves according to claim 1, characterized in that: The frame is equipped with sliding blocks on both sides of the worktable, and the two spindle boxes are respectively fixed on the two sliding blocks.

3. The high-precision double-head milling machine for valves according to claim 2, characterized in that: When the monitored value of the eddy current displacement sensor reaches the first preset threshold, the two slides simultaneously drive their respective spindle boxes to actively retract away from the worktable.

4. The high-precision double-head milling machine for valves according to claim 1, characterized in that: Two hydraulic push rods are fixed on the spindle box, and the telescopic ends of the two hydraulic push rods are respectively fixedly connected to two clamping blocks.

5. A high-precision double-head milling machine for valves according to claim 1, characterized in that: The clamping surface of the clamping block is an arc surface that fits against the outer ring of the spare bearing.

6. A high-precision double-head milling machine for valves according to claim 1, characterized in that: When the flexible conductive tape is in a straightened state, the end height of the clamping block corresponds to the protrusion.

7. A high-precision double-head milling machine for valves according to claim 1, characterized in that: The main shaft is fitted with a first bearing and a second bearing. The outer rings of the first bearing and the second bearing are both fixed inside the main shaft housing. The first bearing is located on the main shaft near the milling cutter head, and the second bearing is located on the main shaft away from the milling cutter head.

8. A high-precision double-head milling machine for valves according to claim 7, characterized in that: The spare bearing is located between the first bearing and the second bearing, close to the first bearing.

9. A high-precision double-head milling machine for valves according to claim 1, characterized in that: After the two clamping blocks are closed and clamped, if the monitoring value of the eddy current displacement sensor is still higher than the second preset threshold, the clamping blocks continue to advance the second preset distance.

10. A high-precision double-head milling machine for valves according to claim 9, characterized in that: If, after the clamping block has advanced a second preset distance, the monitoring value of the eddy current displacement sensor is still higher than the second preset threshold, both spindles will stop rotating and the machine will be shut down for maintenance.

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