Eccentric cutter, screw pump stator machining device and machining method

Abstract

The invention belongs to the technical field of screw pump stator machining, and mainly relates to an eccentric cutter and a screw pump stator machining device and method. The eccentric cutter comprises a cutter bar shaft and a cutter head fixed to one end of the cutter bar shaft, and further comprises a cutter bar sleeve connected to the periphery of the cutter bar shaft in a sleeving mode, the cutter bar shaft is eccentrically arranged relative to the center of the cutter bar sleeve, the periphery of the cutter bar sleeve is of a spiral structure, and the spiral structure is used for being matched with a spiral face of a stator inner cavity. The cutter bar sleeve is used for increasing the radial size of the cutter bar shaft so as to reduce polarization of the cutter head. Due to the fact that the cutter bar sleeve is connected to the cutter bar shaft in a sleeved mode, the overall radial size of the cutter bar shaft is directly increased, the structural rigidity of the cutter bar shaft can be remarkably improved due to increase of the radial size, bending or vibration generated by stress in the cutting process is reduced, and therefore the stability of the cutter head in the working process is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of screw pump stator processing, and mainly relates to an eccentric cutter, a screw pump stator processing device and a processing method. Background Art

[0002] The stator and rotor of the screw pump work together to transport the medium. The inner cavity of the stator is a single-head or multi-head spiral surface, and the processing accuracy of the spiral surface is required to be high. If there is a large error, it will not be able to adapt to the rotor, which is prone to large leakage and reduces the transportation efficiency of the screw pump.

[0003] The stator of a screw pump is typically made of rubber or metal. Rubber stators can be integrally molded using a mold, while metal stators require machining using a machine tool. Because the stator is a long, axial workpiece, excessively long toolholders are unstable when inserting a tool into the metal stator for milling, leading to significant deflection and displacement, causing the cutter head to deviate from its original position and increasing machining errors. While thickening the toolholder can alleviate this problem, in some stators with smaller inner diameters or multi-head screw pumps, thickening the toolholder is not feasible due to the size limitations of the spiral structure.

[0004] Chinese invention patent CN110303306B discloses a method for machining a single-helix metal screw pump stator. When the stator segments are long, the tool bar is insufficiently strong. To ensure machining accuracy, machining is performed from one end before proceeding to the other. This prevents tool vibration or tool bar deformation, which can lead to substandard machining accuracy and taper. While this solution addresses the issue of tool bar stability, because machining the stator's internal cavity involves two separate cuts, the intermediate butt joint is likely to deviate, preventing perfect alignment. Summary of the Invention

[0005] The present invention provides an eccentric tool, a screw pump stator processing device and a processing method, so as to solve the problem of poor tool stability when processing the spiral surface of the stator in the prior art.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions: An eccentric tool includes a tool arbor shaft and a cutter head fixed to one end of the tool arbor shaft, and also includes a tool arbor sleeve sleeved on the outer periphery of the tool arbor shaft. The tool arbor shaft is arranged eccentrically relative to the center of the tool arbor sleeve. The outer periphery of the tool arbor sleeve is a spiral structure, which is used to adapt to the spiral surface of the stator inner cavity. The tool arbor sleeve is used to thicken the radial dimension of the tool arbor shaft to reduce the polarization of the cutter head.

[0007] It has the following beneficial effects: by sleeve-fitting the tool arbor sleeve on the tool arbor shaft, the overall radial dimension of the tool arbor shaft is directly increased. The increase in the radial dimension can significantly improve the structural rigidity of the tool arbor shaft, reduce the bending or vibration caused by force during the cutting process, and thus enhance the stability of the cutter head during operation.

[0008] Furthermore, the helical lead of the tool arbor sleeve is consistent with the lead of the stator inner cavity.

[0009] The invention has the following beneficial effects: during processing, the tool rod sleeve can smoothly enter the inner cavity of the spiral, avoiding the influence of the specifications of the inner cavity on the processing of the cutter head; at the same time, the tool rod sleeve can also better fit the inner cavity, better assist in supporting the tool rod shaft, and ensure the stability of the cutter head during processing.

[0010] Furthermore, a spacer is provided on the outer circumferential surface of the tool rod shaft, and the tool rod sleeve is sleeved on the tool rod shaft through the spacer.

[0011] The invention has the following beneficial effects: through isolation, the direct friction loss between the tool shaft and the tool sleeve is reduced, the tool shaft and the tool sleeve are effectively protected, the service life of both is extended, and equipment shutdown or reduction in processing accuracy due to friction damage is avoided.

[0012] Furthermore, the spacer is a bearing.

[0013] The invention has the following beneficial effects: the bearing can make the arbor sleeve and the arbor shaft rotate directly with a very small friction coefficient, so that the relative rotation between the arbor shaft and the arbor sleeve is smoother and more stable.

[0014] Furthermore, the spacer is an anti-wear bushing.

[0015] The invention has the following beneficial effects: the wear rate of the wear-resistant bushing is slow and uniform, and the fitting clearance between the tool arbor shaft and the tool arbor sleeve can be kept stable for a long time. The clearance will not suddenly increase due to frequent use in a short period of time, thus avoiding the decrease in stability caused by the attenuation of fitting accuracy.

[0016] Furthermore, there is a gap between the end of the shank sleeve and the cutter head.

[0017] The invention has the following beneficial effects: by setting the interval, the possibility of contact between the tool rod sleeve and the tool head is eliminated, ensuring that the tool head can rotate independently without hindrance, avoiding jamming and vibration caused by friction, and ensuring the stability of the tool head during cutting.

[0018] Furthermore, the tool rod shaft has a stop step, and the upper end of the cutter head abuts the stop step. The tool rod shaft also has a threaded section located at the lower end of the cutter head, and a tightening nut is spirally connected to the threaded section. The tightening nut is used to press the cutter head against the stop step to improve the stability of the cutter head.

[0019] It has the following beneficial effects: the stop step provides axial restriction for the cutter head and clarifies the axial installation position of the cutter head; the top pressure generated by the tightening nut through the threaded connection firmly clamps the cutter head between the stop step and the tightening nut, forming front and rear end restrictions of the cutter head. This restriction can completely offset the axial movement trend generated by the cutting force. At the same time, the pre-tightening force of the threaded connection can limit the radial shaking of the cutter head through friction, ensuring that the cutter head always remains relatively stationary with the tool arbor shaft during high-speed rotation and cutting, fundamentally eliminating processing deviations caused by fixation failure.

[0020] Furthermore, the outer periphery of the tool rod sleeve is a conical spiral structure, which is used for processing the tapered inner cavity of the stator, and the taper of the tool rod sleeve is equal to or smaller than the taper of the stator inner cavity, and the smaller end of the tool rod sleeve of the conical spiral structure is close to the cutter head.

[0021] The invention has the following beneficial effects: the taper of the tool rod sleeve must be equal to or smaller than the taper of the stator inner cavity, otherwise the inner cavity will interfere with the tool rod sleeve; The overall thickness of the tool shank sleeve with a conical spiral structure is larger, which ensures that the tool shank sleeve can resist external forces with sufficient rigidity throughout the entire processing stroke, provide stable support for the tool shank shaft, and ensure the stability of the cutter head during processing.

[0022] The screw pump stator processing device includes a machine tool, which includes a chuck and a spindle. The chuck is used to clamp the stator and drive it to rotate. The spindle is used to connect the tool to drive the tool to rotate. The tool is the eccentric tool mentioned above. The spindle is used to coaxially fix the tool rod shaft connected to the eccentric tool to drive the cutter head to rotate and cut out the inner cavity of the stator.

[0023] The screw pump stator processing method is applied to the screw pump stator processing device to process the stator, comprising the following steps: After the cutter head completes a stroke on a horizontal plane each time, it rotates and moves a set distance z1 in the axial direction of the stator, and at the same time the stator rotates a set angle θ1. After reaching the next horizontal plane, it repeats a stroke on the horizontal plane until the entire stator inner cavity is machined. One stroke means that the cutter head completes one horizontal plane according to the set tool path while the stator rotates one circle. Alternatively, after the cutter head completes a stroke along the spiral line of the stator inner cavity, the tool is offset a certain distance along the horizontal route in the stator inner cavity, which serves as a new starting point, and the next stroke processing is repeated until the entire stator inner cavity is processed. One stroke means that the cutter head moves the length of the stator inner cavity in the axial direction of the stator while the stator rotates multiple times. Alternatively, the cutter head rotates and moves along the axial direction of the stator according to the set tool path, and the stator rotates one circle at the same time, completing the processing of one stroke of the stator inner cavity. The cutter head continues to move along the axial direction of the stator according to the above process, performing multiple strokes of processing until the entire stator inner cavity is processed, and the length of the multiple strokes is equal to the length of the stator inner cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of the eccentric tool from the first perspective; Figure 2 This is a structural diagram of the eccentric tool from the second perspective; Figure 3 It is the radial cross-sectional view of the eccentric tool; Figure 4 It is a schematic diagram of part of the structure when the eccentric tool is cutting; Figure 5 It is a partial cross-sectional view of the axial direction of the eccentric tool; Figure 6 for Figure 5 Enlarged view of point A in the middle; Figure 7 This is a schematic diagram of the structure when the eccentric tool is machining the stator; Figure 8 This is the axial cross-sectional view when the eccentric tool is machining the stator; Figure 9 This is the axial cross-sectional view when the eccentric tool of the first taper is machining the tapered inner cavity; Figure 10 This is the axial cross-sectional view when the eccentric tool with the second taper is machining the tapered inner cavity.

[0025] Description of reference numerals: 1. Tool arbor sleeve; 2. Tool head; 3. Jack nut; 4. Tool arbor shaft; 5. Stator; 6. Eccentric tool; 7. Chuck; 8. Inner cavity; 9. Stop step. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0027] Various non-limiting embodiments of the present invention are described below. The numbers of any elements in the accompanying drawings are for illustrative purposes only and are not intended to be limiting, and any nomenclature is for distinction only and does not have any limiting meaning. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other unless there is a conflict.

[0028] Example of eccentric tool like Figure 1-Figure 5 As shown, the eccentric tool 6 is used to machine the spiral inner cavity 8 of the screw pump stator 5. The eccentric tool 6 includes a tool shaft 4 and a cutter head 2 fixed to one end of the tool shaft 4. The tool shaft 4 is coaxially fixed to the main shaft of the machine tool. The rotation of the main shaft drives the tool shaft 4 to rotate, thereby driving the cutter head 2 to rotate and cut out the inner cavity 8 of the stator 5. A tool sleeve 1 is sleeved on the outer periphery of the tool shaft 4. The tool shaft 4 is arranged eccentrically relative to the center of the tool sleeve 1. The main shaft does not drive the tool sleeve 1 to rotate. However, when the main shaft drives the tool shaft 4 to rotate, the tool sleeve 1 and the tool shaft 4 will rotate relative to each other. By sleeved on the tool shaft 4, the radial dimension of the tool shaft 4 is increased, the stability of the cutter head 2 during operation is improved, and the vibration of the cutter head 2 when machining the inner cavity 8 is reduced. Because the inner cavity 8 to be machined is spiral, the tool sleeve 1 needs to have a spiral structure that can adapt to the inner cavity 8 to more stably assist the cutter head 2 in machining. The tool rod sleeve 1 is used to press the inner cavity 8 of the stator 5, so that it can be used to assist in supporting the tool rod shaft 4 and increase the stability of the tool head 2 during processing.

[0029] In this embodiment, Figure 3 As shown, the eccentric arrangement means that the eccentric tool 6 has an eccentricity e, and the eccentricity e refers to the maximum envelope circle ( Figure 3 The distance between the center of the circle (the dotted line circle in the figure) and the center of the tool arbor axis 4.

[0030] A major reason for the poor stability of the eccentric cutter 6 in the prior art is the insufficient rigidity of the arbor shaft 4, which can easily vibrate or deform under stress during high-speed cutting. However, this embodiment directly increases the overall radial dimension of the arbor shaft 4 by attaching the arbor sleeve 1 to the arbor shaft 4. This increased radial dimension significantly improves the structural rigidity of the arbor shaft 4, reducing bending or vibration caused by stress during cutting, thereby enhancing the stability of the cutter head 2 during operation.

[0031] Because the inner cavity 8 of the stator 5 is spiral, if the auxiliary structure does not match the shape of the inner cavity 8, it is easy to cause gaps or misalignment during the processing process, causing the eccentric tool 6 to wobble. However, the tool shank 1 has a spiral structure that adapts to the inner cavity 8 and can precisely fit the spiral inner cavity 8, avoiding relative displacement or gap wobble caused by shape mismatch. The tool shank 1 always maintains a stable fit with the inner cavity 8 when rotating relative to the tool shank shaft 4, further restricting the offset space of the eccentric tool 6 and improving stability.

[0032] During the cutting process, the cutting force applied to the cutter head 2 causes the tool arbor shaft 4 to deflect or vibrate. The tool arbor sleeve 1 reduces the deflection caused by the force by increasing the radial dimension of the tool arbor shaft 4, thereby helping to improve the stability of the cutter head 2 during machining.

[0033] like Figure 7 、 Figure 8 As shown, the spiral lead of the tool rod sleeve 1 is consistent with the lead of the inner cavity 8 of the stator 5. In this way, during processing, the tool rod sleeve 1 can smoothly enter the spiral inner cavity 8, avoiding the size of the inner cavity 8 affecting the processing of the cutter head 2.

[0034] In this embodiment, if the leads of the tool shank 1 and the inner cavity 8 are inconsistent, misalignment interference will occur during their axial relative motion. For example, the distance the tool shank 1 advances during one rotation will not match the distance the inner cavity 8 travels during one spiral rotation. This can cause the tool shank 1 to get stuck when entering the inner cavity 8, causing it to squeeze the inner wall of the inner cavity 8 or creating an excessive gap, directly hindering the continuity of the machining process. However, consistent leads ensure that the tool shank 1 and the inner cavity 8 are synchronized in their axial motion. When the tool shank 1 rotates relative to the tool shaft 4, it can smoothly fit into the inner cavity 8 along its spiral trajectory, avoiding mechanical interference caused by lead differences and ensuring the stability of the machining process.

[0035] A spacer is provided on the outer circumference of the tool rod shaft 4, and the tool rod sleeve 1 is sleeved on the tool rod shaft 4 through the spacer to prevent the tool rod shaft 4 from direct contact and friction with the tool rod sleeve 1 when the tool rod shaft 4 rotates, thereby preventing damage to the tool rod shaft 4.

[0036] In this embodiment, the arbor shaft 4 and the arbor sleeve 1 rotate relative to each other. If they were in direct contact, friction would wear the contact surface between them. Long-term use could cause the outer diameter of the arbor shaft 4 to decrease, the inner diameter of the arbor sleeve 1 to increase, or even cause local deformation. The spacer, acting as an intermediate medium, transforms direct contact between the two into indirect contact between the spacer and the arbor sleeve. This isolation reduces direct friction losses between the arbor shaft 4 and the arbor sleeve 1, effectively protecting the arbor shaft 4 and the arbor sleeve 1, extending their service life, and preventing equipment downtime or reduced machining accuracy due to friction damage.

[0037] Direct contact friction not only damages parts but can also create uneven friction due to rough contact surfaces and assembly errors, leading to jitter and jerkiness in the relative rotation between the tool arbor shaft 4 and the tool arbor sleeve 1. Spacers reduce the friction coefficient of the contact surface, making relative rotation smoother and ensuring that the tool arbor sleeve 1 can continue to perform its auxiliary function stably.

[0038] In this embodiment, the spacer is a bearing, which enables the arbor sleeve 1 and the arbor shaft 4 to rotate directly with a very small friction coefficient, making the relative rotation between the arbor shaft 4 and the arbor sleeve 1 smoother and more stable.

[0039] In this embodiment, the bearing replaces sliding friction with rolling friction, and the friction coefficient is much lower than direct contact, which can make the relative rotation of the tool rod shaft 4 and the tool rod sleeve 1 almost smooth, avoiding jamming caused by excessive friction resistance. The low resistance characteristic of the bearing can reduce energy loss during rotation, prevent the tool rod shaft 4 from vibrating slightly due to friction changes, and indirectly ensure the stability of the tool head 2 processing.

[0040] The inner ring, outer ring and rolling elements of the bearing are precisely machined to strictly control the radial and axial clearances, ensuring that the relative rotation between the tool shaft 4 and the tool sleeve 1 is always within the preset trajectory, reducing eccentric shaking caused by excessive or uneven clearances.

[0041] For the high-speed relative rotation that may occur during the processing, the structural strength and wear resistance of the bearing can withstand high-frequency friction without failure, avoiding performance degradation caused by long-term high-speed friction, and ensuring that low-friction, high-smooth rotation can be maintained under complex working conditions.

[0042] In other embodiments, the spacer is a wear-resistant bushing, which can ensure that the arbor shaft 4 and the arbor sleeve 1 can be used stably for a long time, thereby reducing the frequency of damage to the arbor shaft 4 .

[0043] The anti-wear bushing directly withstands the continuous friction between the arbor shaft 4 and the arbor sleeve 1, preventing the arbor shaft 4 from being worn, scratched, or having its dimensional accuracy reduced. The anti-wear bushing can significantly reduce the frequency of damage to the arbor shaft 4 and reduce the cost of replacing the arbor shaft 4.

[0044] The wear rate of the wear-resistant bushing is slow and uniform, which can keep the fitting clearance between the arbor shaft 4 and the arbor sleeve 1 stable for a long time. The clearance will not suddenly increase due to frequent use in a short period of time, thus avoiding the decrease in stability caused by the attenuation of fitting accuracy.

[0045] Compared with bearings, anti-wear bushings have a simpler structure, are more adaptable to installation space and working conditions, are less likely to fail due to jamming of complex structures, and can maintain stable performance in relatively harsh processing environments.

[0046] There is a gap between the end of the shank sleeve 1 and the cutter head 2 to prevent the shank sleeve 1 and the cutter head 2 from rubbing against each other when the cutter head 2 rotates the rod, thereby preventing the shank sleeve 1 from affecting the rotation of the cutter head 2.

[0047] Cutting head 2 is directly involved in cutting and requires high-speed, stable rotation, while tool holder 1 is not driven by the spindle. If there were no gap between the two, rotating cutting head 2 would rub against the end of tool holder 1. This friction would not only cause wear on cutting head 2 or the end of tool holder 1 but also generate additional frictional resistance, disrupting the rotation rhythm of cutting head 2 and even causing high-frequency vibration. By providing a gap, the possibility of contact between tool holder 1 and cutting head 2 is eliminated, ensuring that cutting head 2 can rotate independently and unimpeded, avoiding friction-induced jamming and vibration, and ensuring the stability of cutting head 2.

[0048] The spacing between the tool rod sleeve 1 and the cutter head 2 allows the cutter head 2 to focus on the cutting action without being disturbed by the tool rod sleeve 1, further ensuring the processing accuracy of the spiral inner cavity 8 of the stator 5.

[0049] like Figure 5 、 Figure 6 As shown, a stop step 9 is provided on one end of the tool arbor shaft 4, and the upper end of the cutter head 2 abuts the stop step 9. The tool arbor shaft 4 also has a threaded section located at the lower end of the cutter head 2, and a tightening nut 3 is threadedly connected to the threaded section. The tightening nut 3 rotates to press the cutter head 2 onto the stop step 9, thereby fixing the cutter head 2 at one end of the tool arbor shaft 4 and ensuring the stability of the cutter head 2 during processing.

[0050] During the cutting process, the cutter head 2 is subjected to continuous axial and radial cutting forces. If it is not firmly fixed, it is easy to loosen, deviate or even fall off. The stop step 9 provides an axial limit for the cutter head 2, clarifying the axial installation position of the cutter head 2; the top nut 3 generates a top pressure through the threaded connection, which firmly clamps the cutter head 2 between the stop step 9 and the top nut 3, forming a front and rear end limit for the cutter head 2. This restriction can completely offset the axial movement trend caused by the cutting force. At the same time, the preload force of the threaded connection can limit the radial shaking of the cutter head 2 through friction, ensuring that the cutter head 2 always remains relatively stationary with the arbor shaft 4 during high-speed rotation and cutting, fundamentally eliminating processing deviations caused by fixation failure.

[0051] The stopper step 9 ensures that the axial position of the cutter head 2 remains highly consistent each time it is installed, while the pressing action of the locking nut 3 prevents position fluctuations caused by installation clearance. This minimizes radial runout and axial position errors of the cutter head 2, ensuring the relative position accuracy of the cutter head 2 and the inner cavity 8 of the stator 5 during each cutting operation.

[0052] In this embodiment, the cutter head 2 is a consumable part and requires replacement or resharpening after extended cutting. The threaded connection between the jack nut 3 and the arbor shaft 4 facilitates assembly and disassembly. Simply loosen the jack nut 3 to remove the cutter head 2, and re-tighten it after replacement. This significantly reduces tool change time and improves tool utilization. Furthermore, this structure allows for interchangeable cutter heads 2 of varying specifications based on processing requirements, enhancing the versatility of the eccentric tool 6.

[0053] In other embodiments, Figure 9 、 Figure 10 As shown, the outer periphery of the toolholder 1 has a tapered spiral structure, which is used to machine the tapered inner cavity 8 of the stator 5. The taper of the toolholder 1 is equal to or less than the taper of the inner cavity 8 of the stator 5. The smaller end of the toolholder 1 with the tapered spiral structure is closer to the cutter head 2, while the larger end is closer to the spindle. The toolholder 1 with the tapered spiral structure is thicker overall, which is equivalent to increasing the radial dimension of the toolholder shaft 4, thereby improving the stability of the cutter head 2 during machining.

[0054] The inner cavity 8 of the stator 5 is a tapered spiral, and the taper of the tool rod sleeve 1 must be equal to or smaller than the taper of the inner cavity 8 of the stator 5 , otherwise the inner cavity 8 will interfere with the tool rod sleeve 1 .

[0055] The tool rod sleeve 1 with a conical spiral structure has a larger overall thickness, which ensures that the tool rod sleeve 1 can resist external forces with sufficient rigidity throughout the entire processing stroke, provide stable support for the tool rod shaft 4, and ensure the stability of the cutter head 2 during processing.

[0056] During use, the machine tool drives the tool rod shaft 4 to rotate, driving the cutter head 2 to rotate, wherein the tool rod sleeve 1 sleeved on the tool rod shaft 4 increases the diameter of the tool rod shaft 4, thereby preventing the tool rod shaft 4 from shaking when the cutter head 2 is processed, thereby enhancing the stability of the cutter head 2 during processing.

[0057] Embodiment of screw pump stator processing device like Figure 7 、 Figure 8 As shown, a screw pump stator machining apparatus includes a machine tool, such as a four-axis or five-axis machine tool. The machine tool includes an eccentric tool 6, a drive mechanism, a chuck 7, and a spindle. The drive mechanism can respectively drive the chuck 7 and the spindle to rotate. The chuck 7 is used to clamp the stator 5 and drive its rotation. The spindle is capable of three-dimensional movement and is used to connect to the tool to drive its rotation. The tool is the eccentric tool 6 mentioned above. The spindle is used to coaxially fix the tool shaft 4 connected to the eccentric tool 6. The spindle drives the cutter head 2 to rotate and cut the inner cavity 8 of the stator 5.

[0058] Embodiment of the screw pump stator processing method The screw pump stator processing method is applied to the screw pump stator processing device, the stator 5 is vertically clamped on the machine tool, and an eccentric tool 6 is used to process along the spiral surface of the inner cavity 8 of the stator 5.

[0059] In this embodiment, after each stroke on a horizontal plane, the cutter head 2 rotates a set distance z1 in the axial direction of the stator 5. Simultaneously, the stator 5 rotates a set angle θ1. After reaching the next horizontal plane, the cutter head 2 repeats the stroke on that plane until the entire internal cavity 8 of the stator 5 is machined. Assuming the lead of the stator 5 is L, the relationship between z1 and θ1 is L / z1 = 360° / θ1.

[0060] In this embodiment, one stroke means that the tool head 2 processes a horizontal surface according to a set tool path while the stator 5 rotates one circle.

[0061] In other embodiments of screw pump stator machining methods, after the cutter head 2 completes a stroke along the spiral line of the stator 5 internal cavity 8, the eccentric cutter 6 is offset horizontally within the stator 5 internal cavity 8 by a certain distance, which serves as a new starting point. The next stroke is then repeated until the entire stator 5 internal cavity 8 is machined. A stroke refers to the length of the stator 5 internal cavity 8 that the cutter head 2 moves axially along the stator 5 while the stator 5 rotates multiple times.

[0062] In other embodiments of the screw pump stator machining method, the cutter head 2 rotates and moves along the axial direction of the stator 5 according to a set tool path. The stator 5 rotates one circle at a time, completing the machining of one internal cavity 8 of the stator 5. The cutter head 2 continues to move along the axial direction of the stator 5 according to the above process, performing multiple machining strokes until the entire internal cavity 8 of the stator 5 is machined. The length of each multiple machining stroke is equal to the length of the internal cavity 8 of the stator 5.

Claims

1. An eccentric tool, comprising a tool shaft and a tool head fixed to one end of the tool shaft, characterized in that: It also includes a tool rod sleeve that is sleeved on the outer periphery of the tool rod shaft. The tool rod shaft is arranged eccentrically relative to the center of the tool rod sleeve. The outer periphery of the tool rod sleeve is a spiral structure, which is used to adapt to the spiral surface of the stator inner cavity. The tool rod sleeve is used to thicken the radial dimension of the tool rod shaft to reduce the polarization of the cutter head.

2. The eccentric tool according to claim 1, characterized in that The helical lead of the tool arbor sleeve is consistent with the lead of the stator inner cavity.

3. The eccentric tool according to claim 1, characterized in that A spacer is provided on the outer circumferential surface of the knife rod shaft, and the knife rod sleeve is sleeved on the knife rod shaft through the spacer.

4. The eccentric tool according to claim 3, characterized in that The spacer is a bearing.

5. The eccentric tool according to claim 3, characterized in that The spacer is an anti-wear bushing.

6. The eccentric tool according to claim 1, characterized in that There is a gap between the end of the cutter rod sleeve and the cutter head.

7. The eccentric tool according to any one of claims 1 to 6, characterized in that: The tool rod shaft is provided with a stop step, and the upper end of the cutter head abuts against the stop step. The tool rod shaft also has a threaded section located at the lower end of the cutter head, and a tightening nut is spirally connected to the threaded section. The tightening nut is used to press the cutter head against the stop step to improve the stability of the cutter head.

8. The eccentric tool according to any one of claims 1 to 6, characterized in that: The outer periphery of the tool rod sleeve is a conical spiral structure, which is used for processing the tapered inner cavity of the stator. The taper of the tool rod sleeve is equal to or smaller than the taper of the stator inner cavity. The smaller end of the tool rod sleeve with the conical spiral structure is close to the cutter head.

9. A screw pump stator processing device, comprising a machine tool, the machine tool comprising a chuck and a spindle, the chuck being used to clamp the stator and drive it to rotate, the spindle being used to connect a tool to drive the tool to rotate, characterized in that: The tool is an eccentric tool as described in any one of claims 1 to 8.

10. A method for processing a screw pump stator, characterized in that: The screw pump stator processing device according to claim 9 is used to process the stator, comprising the following steps: After the cutter head completes a stroke on a horizontal plane each time, it rotates and moves a set distance z1 in the axial direction of the stator, and at the same time the stator rotates a set angle θ1. After reaching the next horizontal plane, it repeats a stroke on the horizontal plane until the entire stator inner cavity is machined. One stroke means that the cutter head completes one horizontal plane according to the set tool path while the stator rotates one circle. Alternatively, after the cutter head completes a stroke along the spiral line of the stator inner cavity, the tool is offset a certain distance along the horizontal route in the stator inner cavity, which serves as a new starting point, and the next stroke processing is repeated until the entire stator inner cavity is processed. One stroke means that the cutter head moves the length of the stator inner cavity in the axial direction of the stator while the stator rotates multiple times. Alternatively, the cutter head rotates and moves along the axial direction of the stator according to the set tool path, and the stator rotates one circle at the same time, completing the processing of one stroke of the stator inner cavity. The cutter head continues to move along the axial direction of the stator according to the above process, performing multiple strokes of processing until the entire stator inner cavity is processed, and the length of the multiple strokes is equal to the length of the stator inner cavity.

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