A tooling and processing method for the final grinding of a hollow cast iron scroll plate

Abstract

The present application relates to a precision parts processing tooling technical field of scroll compressor, especially in a kind of hollow cast iron scroll disc final grinding tooling and processing method, containing tooling base, positioning support unit, pre-guide feeding unit and circumferential clamping unit.The tooling base is the hollow square structure of top, front end opening, and pre-guide feeding unit installation cavity is equipped in inner chamber bottom;Positioning support unit is arranged in base top, containing positioning support plate, cylindrical positioning pin, rhombic positioning pin, support plate supports scroll top plane and is equipped with grinding wheel avoidance through-hole, two positioning pins are matched with scroll disc reference hole.Pre-guide feeding unit is composed of hydraulic oil cylinder, conical surface guide push rod, push rod is adapted scroll disc bottom eccentric positioning hole, and the center deviation of workpiece is corrected and pre-guided.Circumferential clamping unit contains at least three groups of clamping cylinders arranged along the circumference of base, and the piston rod top end pressure head is pressed against scroll disc outer edge bottom.This tooling matches workpiece design reference, and reduces the cumulative processing error caused by reference conversion.

Description

Technical Field

[0001] This invention relates to the field of precision machining tooling technology for scroll compressor parts, and particularly to a tooling and machining method for final grinding of hollow cast iron scroll discs. Background Technology

[0002] The cast iron scroll plate is a core sealing component of the compressor. It is thicker at the top and thinner at the bottom, with a hollow cavity in the middle, making it a easily deformable precision casting. The industry-standard machining process consists of three steps: Step 1: Using a double-end face grinder, simultaneously grind the top plane of the scroll plate and the bottom plane of the workpiece on both sides to ensure parallelism of the two end faces; Step 2: Using a special reamer for integrated drilling and reaming, precision machine the two Φ6H6 reference positioning holes on the top plane of the scroll plate; Step 3: The final machining step, using a high-precision three-axis vertical machining center with a grinding wheel and CNC trajectory interpolation grinding to grind the scroll profile and the bottom surface of the scroll plate. This step completes the machining of the finished product, without any subsequent grinding steps.

[0003] Existing traditional tooling suffers from multiple irreconcilable technical contradictions: 1. Conventional tooling uses the bottom plane of the workpiece as the positioning datum, which is convenient for machining. However, the design datum of the volute profile drawing is the top plane of the volute plus the top datum hole, which causes the positioning datum to not coincide with the design datum. After grinding, a large number of profiles are scrapped due to excessive tolerance. 2. If the positioning is changed to one surface with two pins to eliminate the reference error, the hollow cavity of the scroll disk is very prone to compression warping and profile deviation under the action of the central top support force; 3. The bottom surface of the vortex has been precision ground in the previous process. The internal cavity of the traditional tooling is entirely made of 42CrMo metal. When the workpiece is placed manually, the precision-machined bottom surface is in direct hard contact with the metal, which is very easy to produce scratches and bumps, resulting in a high workpiece scrap rate. 4. Traditional pre-positioning structures are driven by cylinders, resulting in large start-stop impacts and short service life due to long-term high-frequency reciprocating operation; 5. Tooling bases and positioning support plates are mostly made of cast iron or ordinary 45# steel. Under long-term high-frequency grinding vibration of the grinding wheel, the reference surface is prone to flatness drift. Traditional bases are generally reinforced with thickened ribs, resulting in a bulky frame structure that easily obstructs the 360° all-round interpolation trajectory of the grinding wheel, causing tool interference. 6. The tooling is only set with single-point or two-point clamping, resulting in poor anti-vibration performance during grinding. The reciprocating impact of the grinding wheel will form vibration marks on the surface of the volute teeth, leading to large batch size dispersion.

[0004] In summary, existing machining fixtures cannot simultaneously meet multiple requirements such as datum coincidence, anti-deformation of hollow workpieces, anti-collision of precision ground bottom surface, high fixture rigidity, no tool interference, and automated production, and have obvious technical defects.

[0005] Therefore, there is a need to provide a tooling and machining method for the final grinding of hollow cast iron scroll plates, which can protect the finished surface of the workpiece while realizing low-pressure pre-guiding of the workpiece, precise positioning of one side and two pins, circumferential multi-point clamping, and sequential linkage of oil and gas actions, so as to improve the positioning accuracy, clamping rigidity and automation level in the final grinding process of the scroll plate. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a tooling and machining method for the final grinding of hollow cast iron scroll disks. The positioning support plate, cylindrical positioning pin and rhomboid positioning pin together form a one-face two-pin positioning structure, which can realize the complete positioning of the scroll disk in six degrees of freedom, so that the workpiece machining datum corresponds to the design datum formed by its datum hole and the top plane of the scroll, and reduces the cumulative error caused by datum conversion.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention discloses a fixture for final grinding of a hollow cast iron scroll disk, comprising a fixture base, a positioning support unit, a pre-guided feeding unit, and a circumferential clamping unit; the fixture base is a hollow square structure with openings at the top and front ends, and the bottom of the inner cavity of the fixture base is provided with an installation cavity for installing the pre-guided feeding unit; the positioning support unit is disposed on the top of the fixture base, comprising a positioning support plate, a cylindrical positioning pin, and a rhombic positioning pin, the positioning support plate being used to support the scroll top plane of the scroll disk, the middle of the positioning support plate being provided with a grinding wheel clearance through hole for the grinding wheel to pass through, and the cylindrical positioning pin and the rhombic positioning pin being disposed at the bottom of the inner wall of the grinding wheel clearance through hole. The cylindrical positioning pin and the rhomboid positioning pin respectively cooperate with the two reference holes on the top of the scroll plate to restrict the translation and rotation of the scroll plate in the horizontal plane, and together with the positioning support plate, restrict the six degrees of freedom of the scroll plate; the pre-guided feeding unit includes a hydraulic cylinder disposed in the mounting cavity and a conical guide push rod connected to the output end of the hydraulic cylinder. The conical guide push rod matches the eccentric positioning hole at the bottom of the scroll plate and is used to center the scroll plate and pre-guide it after it is placed in place; the circumferential clamping unit includes at least three sets of clamping cylinders spaced apart circumferentially along the tooling base. The piston rod of each clamping cylinder is arranged facing the top of the tooling, and the end of the piston rod is provided with a pressure head for pressing against the bottom of the outer edge of the scroll plate.

[0008] The grinding wheel clearance through hole matches the outer diameter of the vortex disk. The inner wall of the grinding wheel clearance through hole has three support blocks arranged in a ring. The bottom of the two support blocks is respectively provided with a cylindrical positioning pin and a diamond positioning pin extending towards the vortex disk.

[0009] The bottom of the inner cavity of the tooling base is provided with a protective plate groove for installing the support protective plate. The middle part of the support protective plate is provided with a push rod clearance hole that matches the inner diameter of the mounting cavity. The top rear end of the support protective plate is provided with a limiting post.

[0010] The tooling base is a 42CrMo alloy steel base that is integrally machined; the supporting protective plate is made of PA66 engineering plastic.

[0011] The inner wall of the grinding wheel clearance through hole is provided with a clamping block and a positioning block that match the clamping groove and positioning groove of the outer wall of the vortex disk.

[0012] The top of the conical guide push rod is provided with a conical guide surface, the cone angle of which is 20°. The conical guide surface is polished and is used to contact the edge of the eccentric positioning hole at the bottom of the scroll disk and to perform radial correction of the scroll disk.

[0013] The clamping cylinders are configured in three groups, and the three groups of clamping cylinders are evenly arranged at 120° intervals along the circumference of the tooling base; the pressure head is made of polyurethane material, and the pressure head cooperates with the pressure head groove at the bottom of the outer edge of the scroll plate.

[0014] The hydraulic cylinder and the clamping cylinder are respectively connected to the oil-gas timing linkage control system, which is used to control the arrival detection, pre-guidance, positioning, clamping, and release and removal of the scroll plate after grinding according to the preset timing sequence. The oil-gas timing linkage control system is connected to the machine tool CNC system and is equipped with workpiece arrival detection signal, clamping pressure detection signal and grinding wheel safety position detection signal. When the workpiece is not detected to be in place or the clamping pressure does not reach the set value, the machine tool CNC system prohibits the start of the grinding program.

[0015] This invention discloses a method for final grinding of hollow cast iron scroll disks using tooling, comprising the following steps: S1. Fully retract the hydraulic cylinder and keep the support plate in a fixed state. Place the scroll plate to be processed on the support plate. S2. After the scroll plate is placed in place, start the hydraulic cylinder to make the conical guide push rod rise at low speed, so that the scroll plate can perform radial correction under the action of the conical guide surface, and rise axially to the positioning position of the positioning support unit. S3. Continue to raise the conical guide push rod at low speed, so that the cylindrical positioning pin and the diamond positioning pin enter the two reference holes of the scroll disk respectively, and make the top plane of the scroll disk fit with the positioning support surface of the three support blocks to complete the positioning of one side and two pins. S4. Start the three sets of clamping cylinders so that the pressure head synchronously presses against the pressure head groove at the bottom of the outer edge of the scroll plate to complete the circumferential clamping of the scroll plate. S5. After confirming that the positioning is completed and the clamping pressure reaches the set value, start the three-axis vertical machining center and use the grinding wheel to pass through the grinding wheel avoidance through hole to perform CNC trajectory grinding on the scroll profile and / or the bottom surface of the scroll. S6. After grinding is completed, the grinding wheel is returned to the safe position, the three sets of clamping cylinders are controlled to retract synchronously, the clamping of the scroll plate is released, and the operator removes the finished scroll plate from the support and protective plate.

[0016] In steps S2 and S3, the thrust applied to the scroll plate by the hydraulic cylinder is no more than 120 N; after clamping is completed in step S4, the conical guide push rod retracts or only maintains a non-load-bearing contact state with the scroll plate to reduce the risk of deformation of the hollow cavity of the scroll plate due to continuous concentrated force.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. Achieve low-impact pre-guiding of the workpiece. The pre-guided feeding unit uses a hydraulic cylinder to drive the conical guide push rod to rise at low speed. The conical guide surface contacts the edge of the eccentric positioning hole at the bottom of the scroll plate, and the component force of the conical surface is used to gradually correct the workpiece.

[0019] Compared with the rapid lifting of ordinary cylinders or the direct pressing of rigid push rods, the speed and output thrust of hydraulic cylinders can be independently adjusted, resulting in smooth operation and less impact. This helps prevent local deformation of the hollow scroll plate due to excessive instantaneous pressing pressure.

[0020] 2. Improve workpiece positioning accuracy The positioning support plate, cylindrical positioning pin, and rhomboid positioning pin together constitute a one-sided, two-pin positioning structure. The positioning support plate, or the support block set on the inner wall of the grinding wheel clearance hole, contacts the top plane of the scroll plate to determine the axial position of the scroll plate and restrict its rotation around the two horizontal axes. The cylindrical positioning pin and the rhomboid positioning pin respectively engage with two reference holes to restrict the movement of the scroll plate in the horizontal plane and its rotation around the vertical axis.

[0021] This enables complete positioning of the six degrees of freedom of the scroll disk, ensuring that the workpiece machining datum corresponds to the design datum formed by its datum hole and the top plane of the scroll, thus reducing the cumulative error caused by datum conversion.

[0022] 3. Avoid over-positioning caused by the positioning structure. The cylindrical locating pin and the rhomboid locating pin respectively mate with the two reference holes of the scroll plate. The cylindrical locating pin is used to determine the position of the workpiece in two horizontal directions, while the rhomboid locating pin, while ensuring the angular positioning of the workpiece, provides compensation space for the hole spacing error and thermal deformation between the two reference holes, which can reduce the problems of over-positioning, jamming, and difficulty in loading and unloading that are easily caused by double cylindrical pin positioning.

[0023] 4. Improve clamping stability during grinding. The circumferential clamping unit includes three sets of clamping cylinders arranged at intervals along the circumference of the tooling base. The piston rod of the clamping cylinder moves upward, causing the pressure head to press against the pressure head groove at the bottom of the outer edge of the scroll plate, thereby pressing the scroll plate against the positioning support unit.

[0024] The three sets of clamping cylinders can clamp the workpiece together from different circumferential positions, so that the workpiece remains stably attached to the positioning support surface during the grinding process, and together with the positioning support unit, they can bear the axial load, radial load, cutting torque and high-frequency vibration generated by the grinding wheel, which helps to reduce the slight displacement of the workpiece and grinding chatter.

[0025] 5. Reduce the risk of workpiece clamping injury The pressure head is made of polyurethane material and mates with the pressure head groove at the bottom of the outer edge of the scroll plate. The polyurethane pressure head has a certain degree of elasticity, which can increase the contact area, disperse local clamping stress, and avoid direct metal-to-metal contact between the clamping parts and the cast iron workpiece, thereby reducing the risk of indentation, bumping, and pinching damage to the outer edge of the workpiece.

[0026] 6. Protect the finished surfaces of the workpiece The bottom of the inner cavity of the tooling base is equipped with a protective plate groove, and the protective plate is fixedly installed in the protective plate groove. The protective plate is made of PA66 engineering plastic. During manual loading and unloading, the scroll plate is supported by the protective plate, which isolates the machined surface of the workpiece from the 42CrMo metal base, reducing the possibility of scratches and collisions during loading and unloading.

[0027] The support and protection plate is a fixed structure, which does not require lifting, pulling or retraction mechanisms. Therefore, the structure is simple, there are few points of failure, and it can be disassembled and replaced individually after wear.

[0028] 7. Ensure smooth movement of the pre-guide push rod A push rod clearance hole is provided in the middle of the supporting protective plate. The conical guide push rod can move upward through the push rod clearance hole and enter the eccentric positioning hole at the bottom of the scroll plate. The push rod clearance hole can prevent the supporting protective plate from blocking the movement of the conical guide push rod, so that the two functions of supporting protection and pre-guiding do not interfere with each other.

[0029] 8. Reduce interference from grinding wheel motion A grinding wheel clearance through hole is provided in the middle of the positioning support plate, and the size of the grinding wheel clearance through hole is adapted to the machining area of ​​the scroll plate. During grinding, the grinding wheel can pass through the grinding wheel clearance through hole and perform trajectory interpolation grinding on the scroll profile and / or the bottom surface of the scroll along a preset program.

[0030] The tooling base adopts a hollow structure with openings at the top and front. The hydraulic lines, pneumatic lines and control joints are at least partially arranged in the concealed pipeline groove, which can reduce the interference of the tooling structure and pipelines on the grinding wheel and the moving parts of the machine tool.

[0031] 9. Improve the long-term stability of tooling datum. The tooling base is made of integrally machined 42CrMo alloy steel, and its bending stiffness, fatigue resistance, and dimensional stability can be improved through quenching and tempering and stress relief treatment. The tooling base is less prone to datum surface shift or overall warping when subjected to long-term grinding vibration and repeated clamping loads, which helps maintain repeatable positioning accuracy during batch processing.

[0032] 10. Prevent the hollow scroll disk from being subjected to continuous concentrated top pressure. The hydraulic cylinder is mainly used for pre-guiding and rough positioning of the workpiece, and the maximum thrust is limited to no more than 120N. After the circumferential clamping unit completes clamping, the conical guide push rod retracts or only maintains a non-load-bearing contact state with the workpiece, and does not bear the main support load and grinding load of the workpiece, which can prevent the conical guide push rod from continuously pressing against the hollow cavity during the grinding process.

[0033] 11. Improve tooling automation and safety The oil-gas timing linkage control system controls the hydraulic cylinders and three sets of clamping cylinders respectively, and is connected to the machine tool CNC system. Based on the workpiece arrival detection signal, clamping pressure detection signal and grinding wheel safety position detection signal, it sequentially executes the actions of workpiece detection, pre-guidance, positioning, clamping, grinding, loosening and picking up.

[0034] When the workpiece is not detected to be in place or the clamping pressure does not reach the set value, the CNC system of the machine tool prohibits the start of the grinding program; when the grinding wheel is not returned to the safe position, the clamping cylinder cannot perform the clamping action, thereby reducing the risk of malfunction and collision. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a top view of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention without the vortex disk; Figure 4 This is a schematic diagram of the present invention with the positioning support unit and the scroll disk removed; Figure 5 This is a schematic diagram of the vortex disk in the present invention; Figure 6 This is a bottom view of the vortex disk in this invention.

[0036] In the attached diagram, 1 is the tooling base, 2 is the positioning support unit, 21 is the positioning support plate, 22 is the cylindrical positioning pin, 23 is the rhomboid positioning pin, 24 is the grinding wheel clearance through hole, 25 is the support block, 26 is the clamping block, 27 is the positioning block, 3 is the pre-guided feeding unit, 31 is the hydraulic cylinder, 32 is the conical guide push rod, 33 is the conical guide surface, 4 is the circumferential clamping unit, 41 is the clamping cylinder, 42 is the piston rod, 43 is the pressure head, 5 is the supporting protective plate, 51 is the push rod clearance hole, 52 is the limiting post, 6 is the scroll plate, 61 is the scroll top plane, 62 is the reference hole, 63 is the eccentric positioning hole, 64 is the clamping groove, 65 is the positioning groove, 66 is the pressure head groove, 11 is the mounting cavity, and 12 is the protective plate groove. Detailed Implementation

[0037] The present invention will be further described below: Please see Figure 1-6 .

[0038] Example 1: Overall Structure of Tooling This embodiment provides a tooling for the final grinding of a hollow cast iron scroll disk. It is installed on the worktable of a high-precision three-axis vertical machining center and is used to perform final grinding on the scroll disk 6 that has undergone previous end face grinding and reference hole machining.

[0039] The tooling includes a tooling base 1, a positioning support unit 2, a pre-guided feeding unit 3, a circumferential clamping unit 4, a support and protection plate 5, and an oil and gas timing linkage control system.

[0040] The scroll plate 6 to be processed is a hollow cast iron scroll plate, which has a scroll top plane 61, two reference holes 62, an eccentric positioning hole 63 located at the bottom, a clamping groove 64 and a positioning groove 65 set on the outer wall, and a pressure head groove 66 set at the bottom of the outer edge.

[0041] In this embodiment, the preliminary processing of the scroll disk 6 includes: fine grinding of the top plane and opposite end faces of the scroll to achieve the specified flatness and parallelism of both end faces; and machining two reference holes 62 on the top of the scroll disk using drilling and reaming or reaming processes. After completing the above preliminary processing, the tooling of this embodiment is used to perform final grinding of the scroll profile and / or the bottom surface of the scroll.

[0042] 1. Tooling base The tooling base 1 is a hollow square structure with openings at the top and front. The top opening is used to install the positioning support unit 2 and form an operating space for the workpiece and grinding wheel. The front opening facilitates the insertion of the scroll plate 6 and the installation and maintenance of the hydraulic cylinder 31, clamping cylinder 41, support and protective plate 5, and corresponding oil and gas pipelines.

[0043] The tooling base 1 is formed by milling an integral 42CrMo alloy steel plate. In one specific embodiment, the planar dimensions of the tooling base 1 are 450mm × 450mm, and the thickness is 57mm. After machining, the tooling base 1 undergoes overall heat treatment and stress relief to improve its strength, bending stiffness, fatigue resistance, and dimensional stability.

[0044] The mounting reference surface of the tooling base 1 is precision ground, and the flatness can be controlled within 0.01mm. No outwardly protruding reinforcing ribs are provided around the tooling base 1 to avoid the reinforcing structure occupying the movement space of the machine tool grinding wheel and spindle.

[0045] A mounting cavity 11 is provided in the middle of the bottom of the inner cavity of the tooling base 1. The mounting cavity 11 is used to vertically install the pre-guided feeding unit 3. The mounting cavity 11 can be formed by mounting holes, mounting grooves and hydraulic cylinder fixing plates provided at the bottom of the tooling base 1.

[0046] The bottom of the inner cavity of the tooling base 1 is also provided with a protective plate groove 12, which is used to install and support the protective plate 5. The protective plate groove 12 limits the horizontal movement of the protective plate 5 and keeps the installation position of the protective plate 5 stable.

[0047] The tooling base 1 may also be equipped with a concealed pipeline groove, in which hydraulic lines, pneumatic lines, electrical lines and control connectors are at least partially housed. The concealed pipeline groove is isolated from the machine tool's moving area to reduce the possibility of interference between the pipelines and the grinding wheel, spindle or other moving parts of the machine tool.

[0048] 2. Positioning support unit The positioning support unit 2 is located on the top of the tooling base 1 and includes a positioning support plate 21, a cylindrical positioning pin 22, a rhomboid positioning pin 23, a grinding wheel clearance through hole 24, a support block 25, and a positioning block 26.

[0049] The positioning support plate 21 is made of 42CrMo quenched and tempered steel plate. In one specific embodiment, the thickness of the positioning support plate 21 is 20mm, and the positioning reference surface of the positioning support plate 21 is precision ground, with its flatness controllable within 0.005mm. The positioning support plate 21 is fixed to the top of the tooling base 1 by multiple sets of equal-height fasteners. Countersunk bolts are preferred fasteners to prevent the bolt heads from extending into the grinding wheel's moving area.

[0050] A grinding wheel clearance through-hole 24 is provided in the middle of the positioning support plate 21. The grinding wheel clearance through-hole 24 is a circular through-hole adapted to the machining contour of the scroll plate 6. In one specific embodiment, the diameter of the grinding wheel clearance through-hole 24 is 280mm. The diameter of the grinding wheel clearance through-hole 24 should ensure that the grinding wheel can pass through and complete linear interpolation, circular interpolation, or compound trajectory interpolation grinding of the scroll profile and the bottom surface of the scroll.

[0051] Three support blocks 25 are spaced circumferentially on the inner wall of the grinding wheel clearance through hole 24. The lower working surfaces of the three support blocks 25 are set at the same height to fit against the top plane 61 of the scroll plate 6. The three support blocks 25 together form a positioning support surface required for positioning.

[0052] In the clamped state, the scroll plate 6 is located below the positioning support plate 21, and the scroll top plane 61 of the scroll plate 6 is in contact with the lower working surface of the three support blocks 25. As a result, the support blocks 25 restrict the scroll plate 6 from moving upward in the vertical direction and restrict the scroll plate 6 from rotating around two mutually perpendicular horizontal axes.

[0053] The support block 25 can be integrally machined with the positioning support plate 21, or it can be detachably installed on the positioning support plate 21. When the support block 25 has a detachable structure, it can be made of wear-resistant materials such as Cr12MoV, and precision ground after quenching. When the support block 25 wears out, it can be removed and replaced separately without replacing the entire positioning support plate 21.

[0054] Cylindrical locating pins 22 and rhomboid locating pins 23 are respectively installed on the bottom of the two support blocks 25. The cylindrical locating pins 22 and rhomboid locating pins 23 are set vertically downward and respectively cooperate with the two reference holes 62 on the top of the scroll disk 6.

[0055] In one specific embodiment, both reference holes 62 are Φ6H6 holes. The cylindrical locating pin 22 and the rhomboid locating pin 23 are made of SKD11 mold steel, and the hardness after integral quenching is HRC62~65. The locating pins and the reference holes 62 adopt a clearance positioning fit so that the locating pins can be smoothly inserted into the corresponding reference holes 62.

[0056] The cylindrical locating pin 22 is used to restrict the scroll plate 6 from moving in two horizontal directions, and the rhomboid locating pin 23 is used to restrict the scroll plate 6 from rotating around the vertical axis. At the same time, it compensates for the hole spacing deviation of the two reference holes 62 to prevent the workpiece from getting stuck due to double pin positioning.

[0057] The mounting end of the locating pin can be threaded externally and can be detachably locked using double nuts. For scroll plates of different specifications or with different reference hole spacings, locating pins of appropriate size and position can be replaced.

[0058] The inner rear side of the grinding wheel avoidance through hole 24 is also provided with a clamping block 26 and a positioning block 27 adapted to the outer wall structure of the scroll plate 6. In this embodiment, a support block 25 located on the rear side also constitutes the clamping block, and its partial contour is adapted to the clamping groove 64 of the outer wall of the scroll plate 6; the positioning block 27 is adapted to the positioning groove 65 of the outer wall of the scroll plate 6.

[0059] The clamping block 26 and the positioning block 27 are mainly used for auxiliary guidance and preventing incorrect assembly during the workpiece lifting process. A predetermined assembly gap can be maintained between the clamping block 26, the positioning block 27 and the corresponding slot to avoid over-positioning that conflicts with the cylindrical positioning pin 22 and the diamond positioning pin 23; and by setting the clamping block 26 and the positioning block 27, coarse positioning can also be performed at a suitable position when the operator sends the scroll plate 6 into the tooling base 1.

[0060] 3. Pre-guided feeding unit The pre-guided feeding unit 3 includes a hydraulic cylinder 31 and a conical guide push rod 32.

[0061] The hydraulic cylinder 31 is vertically installed in the mounting cavity 11 at the bottom center of the tooling base 1. The axis of the hydraulic cylinder 31 corresponds to the predetermined position of the eccentric positioning hole 63 of the scroll plate 6 to be processed. It should be noted that the eccentric positioning hole 63 is eccentrically set relative to the geometric center of the scroll plate 6. Therefore, the hydraulic cylinder 31 can be installed offset relative to the geometric center of the tooling base 1, or the tapered guide push rod 32 can be aligned with the eccentric positioning hole 63 through an offset connection structure.

[0062] The tapered guide push rod 32 is connected to the output end of the hydraulic cylinder 31. The top of the tapered guide push rod 32 is provided with a tapered guide surface 33, and the tapered angle of the tapered guide surface 33 is 20°. The tapered guide surface 33 is polished, and its surface roughness can be controlled within Ra0.8μm to reduce friction and scratches between the tapered guide push rod 32 and the edge of the eccentric positioning hole 63.

[0063] The hydraulic cylinder 31 is connected to an independent hydraulic pressure regulating module, and its rated output thrust can be set to 100N, with a maximum output thrust not exceeding 120N. The rising speed of the hydraulic cylinder 31 can be set to 5-10mm / s, preferably 8mm / s.

[0064] When the hydraulic cylinder 31 is activated, the conical guide push rod 32 extends upward through the push rod clearance hole 51 on the support and protection plate 5. The conical guide surface 33 first contacts the edge of the eccentric positioning hole 63 at the bottom of the scroll plate 6. As the conical guide push rod 32 continues to rise, the conical guide surface 33 generates axial and radial forces on the edge of the hole, thereby causing the scroll plate 6 to gradually rise and roughly correct its planar position and circumferential direction.

[0065] Because the eccentric positioning hole 63 is offset from the geometric center of the scroll disk 6, the cooperation between the conical guide push rod 32 and the eccentric positioning hole 63 can also provide pre-guidance for the circumferential attitude of the scroll disk 6. However, the conical guide push rod 32 is only used for coarse positioning of the workpiece, and the final position of the workpiece is determined by the support block 25, the cylindrical positioning pin 22, and the rhomboid positioning pin 23.

[0066] 4. Circumferential clamping unit The circumferential clamping unit 4 includes at least three sets of clamping cylinders 41. In this embodiment, the clamping cylinders 41 are configured as three sets, and the three sets of clamping cylinders 41 are arranged at 120° intervals along the circumference of the tooling base 1.

[0067] Each clamping cylinder 41 can be fixed in the tooling base 1 by a cylinder bracket. The piston rod 42 of the clamping cylinder 41 is set towards the top of the tooling, that is, the piston rod 42 can extend in an inclined upward or vertical upward direction so that the pressure head 43 presses against the bottom of the outer edge of the scroll plate 6.

[0068] Preferably, the top cross-section of the pressure head 43 has an arc-shaped structure, so that the force exerted by the pressure head 43 has both an upward axial component and a radial component toward the center of the workpiece. The upward axial component makes the vortex top plane 61 stably fit against the lower working surface of the support block 25, and the radial component is used to improve the clamping stability of the workpiece in the horizontal direction.

[0069] A detachable pressure head 43 is provided at the end of the piston rod 42. The pressure head 43 is made of polyurethane material, and the side of it that contacts the scroll plate 6 has a contact profile adapted to the pressure head groove 66. When clamping, the pressure head 43 enters or abuts against the pressure head groove 66 to prevent the pressure head 43 from sliding relative to the workpiece.

[0070] Each set of clamping cylinders 41 is equipped with a pressure regulating valve, and the working pressure of the cylinder can be adjusted within the range of 0.3 to 0.8 MPa, with the standard working pressure set to 0.5 MPa. The three sets of clamping cylinders 41 operate simultaneously through a synchronous control valve group to reduce the possibility of workpiece displacement caused by asynchronous operation of each clamping point.

[0071] The main function of the clamping cylinder 41 is to press the scroll plate 6 against the positioning support unit 2, keeping the top plane 61 of the scroll plate stable against the support block 25. After clamping, the grinding load is transmitted to the machine tool table through the scroll plate 6, support block 25, positioning support plate 21, and tooling base 1, instead of being borne by the hydraulic cylinder 31.

[0072] 5. Supporting protective panels The support plate 5 is installed in the protection plate groove 12 at the bottom of the inner cavity of the tooling base 1. The support plate 5 is made of PA66 wear-resistant engineering plastic and is fixed in the protection plate groove 12 by bolts, positioning posts or other detachable fastening structures.

[0073] The support plate 5 is used to support the scroll plate 6 during manual loading and unloading, so that the surface of the scroll plate 6 that has been finished does not come into direct contact with the metal surface of the tooling base 1.

[0074] The protective plate 5 has a push rod clearance hole 51 in the middle, which corresponds to the movement area of ​​the mounting cavity 11 and the conical guide push rod 32. The size of the push rod clearance hole 51 is larger than the maximum outer diameter of the conical guide push rod 32, so that the conical guide push rod 32 can move up and down without friction.

[0075] A limiting post 52 is provided at the top rear end of the supporting protective plate 5. When the operator places the scroll plate 6, the outer edge of the workpiece can be brought close to or in contact with the limiting post 52, thereby determining the approximate initial placement position of the workpiece and ensuring that the eccentric positioning hole 63 is within the effective guiding range of the conical guide push rod 32.

[0076] The limiting post 52 is only used for rough positioning during manual loading and is not used as the final positioning reference during the grinding process of the scroll plate 6. After the hydraulic cylinder 31 pushes the scroll plate 6 to rise, the workpiece is separated from the support plate 5 and the limiting post 52 or is in a non-load-bearing state, and the final positioning of the workpiece is completed by the positioning support unit 2.

[0077] The support and protective plate 5 adopts a fixed structure and does not have lifting, pulling, or lateral retraction mechanisms. Its shape and installation position avoid the actual machining trajectory of the grinding wheel so that the support and protective plate 5 remains fixed during grinding and will not interfere with the grinding wheel.

[0078] 6. Oil and gas timing linkage control system The oil-gas timing linkage control system is connected to the hydraulic cylinder 31, the three sets of clamping cylinders 41, and the CNC system of the three-axis vertical machining center.

[0079] The hydraulic cylinder 31 is equipped with a hydraulic pressure regulating valve, a flow control valve, and a directional valve. The hydraulic pressure regulating valve is used to limit the maximum output thrust of the hydraulic cylinder 31, the flow control valve is used to control the rising and falling speed of the conical guide push rod 32, and the directional valve is used to control the extension and retraction of the hydraulic cylinder 31.

[0080] The three sets of clamping cylinders 41 are each equipped with a pneumatic pressure regulating valve and controlled by a synchronous pneumatic control circuit. A pressure sensor or pressure switch can be installed in the pneumatic circuit to detect whether the clamping pressure of the clamping cylinders 41 has reached the set value.

[0081] The oil and gas timing linkage control system is configured with the following detection signals: 1. The workpiece positioning detection signal is used to determine whether the scroll plate 6 has been placed in the designated area of ​​the support and protection plate 5; 2. The hydraulic cylinder position detection signal is used to determine whether the conical guide push rod 32 has reached the predetermined guide position; 3. Clamping pressure detection signal, used to determine whether the clamping cylinder 41 has completed reliable clamping; 4. Grinding wheel safety position detection signal, used to determine whether the grinding wheel has exited the workpiece and tooling area; 5. The release and positioning detection signal is used to determine whether the clamping cylinder 41 has fully retracted.

[0082] When no workpiece positioning signal is detected, hydraulic cylinder 31 cannot perform the lifting action; when the clamping pressure does not reach the set value, the machine tool CNC system prohibits the start of the grinding program; when the grinding wheel does not return to the safe position, clamping cylinder 41 cannot perform the loosening action.

[0083] Example 2: The working process of the tooling The final grinding of a hollow cast iron scroll disc using the above-mentioned tooling includes the following stages.

[0084] Phase 1: Tooling standby and manual component placement When the tooling is in standby mode, the hydraulic cylinder 31 is fully retracted, and the conical guide push rod 32 is located below the support and protection plate 5 or inside the push rod clearance hole 51. All three sets of clamping cylinders 41 are in the retracted state, and the pressure head 43 is away from the workpiece placement area.

[0085] The operator places the pre-processed scroll plate 6 on the support and protective plate 5, and brings the outer edge of the workpiece close to the limiting post 52 at the top rear end of the support and protective plate 5. The limiting post 52 keeps the scroll plate 6 in a predetermined rough position and ensures that the eccentric positioning hole 63 is within the guide range of the conical guide push rod 32.

[0086] At this stage, the scroll plate 6 is supported by the PA66 support plate 5, and the machined surface of the workpiece does not directly contact the 42CrMo tooling base 1. The cylindrical locating pin 22 and the rhomboid locating pin 23 have not yet entered the reference hole 62.

[0087] Phase Two: Hydraulic Pre-guidance and Correction After the workpiece positioning detection element detects that the scroll plate 6 has been placed in position, it sends a positioning signal to the oil-gas timing linkage control system. The control system then activates the hydraulic circuit, and the hydraulic cylinder 31 drives the conical guide push rod 32 to move upward at a speed of approximately 8 mm / s.

[0088] The conical guide push rod 32 extends through the push rod clearance hole 51 in the middle of the support and protection plate 5, and the conical guide surface 33 contacts the edge of the eccentric positioning hole 63 at the bottom of the scroll plate 6.

[0089] As the conical guide push rod 32 continues to rise, the conical guide surface 33 applies a progressive force to the edge of the eccentric positioning hole 63, causing the scroll plate 6 to move away from the supporting protective plate 5 and towards the positioning support unit 2. At the same time, the radial component force generated by the conical guide surface 33 corrects the positional deviation of the scroll plate 6, causing the two reference holes 62 to gradually approach the cylindrical positioning pin 22 and the rhomboid positioning pin 23.

[0090] The maximum thrust of the hydraulic cylinder 31 is limited to no more than 120N to avoid applying excessive concentrated top pressure to the hollow cavity of the scroll plate 6.

[0091] Phase Three: Precise Positioning of One Side and Two Pins As the scroll plate 6 continues to rise, the cylindrical positioning pin 22 and the rhomboid positioning pin 23 respectively enter the two reference holes 62 at the top of the scroll plate 6.

[0092] Once the scroll plate 6 has risen to its position, its top plane 61 aligns with the lower working surfaces of the three support blocks 25. The three support blocks 25 form a positioning plane, and the cylindrical positioning pin 22 and the rhomboid positioning pin 23 form a two-pin positioning structure.

[0093] The positioning support surface restricts the scroll disk 6 from moving vertically and rotating around two horizontal axes; the cylindrical positioning pin 22 and the rhomboid positioning pin 23 restrict the scroll disk 6 from moving in the horizontal plane and rotating around the vertical axis, thereby completing the positioning of the scroll disk 6 in six degrees of freedom.

[0094] Meanwhile, the clamping groove 64 and positioning groove 65 on the outer wall of the scroll plate 6 correspond to the clamping block and positioning block 26 on the rear side, respectively, to help confirm the workpiece assembly direction and reduce the possibility of workpiece reverse assembly.

[0095] Phase 4: Circumferential Three-Point Clamping After positioning is completed, the oil and gas timing linkage control system controls the three sets of clamping cylinders 41 to extend synchronously. The piston rod 42 drives the polyurethane pressure head 43 to move upward, so that the three pressure heads 43 respectively enter or press against the pressure head groove 66 at the bottom of the outer edge of the scroll plate 6.

[0096] The upward component of the force applied to the workpiece by the pressure head 43 causes the top plane 61 of the scroll plate 6 to stably adhere to the three support blocks 25, thereby locking the axial position of the workpiece. The top cross-section of the pressure head 43 has an arc-shaped structure, and the radial component of the force applied to the workpiece cooperates with the two locating pins to improve the workpiece's ability to resist horizontal cutting forces and cutting torques.

[0097] Once the pressure sensor detects that the clamping pressure of all three sets of clamping cylinders 41 has reached the set value, the control system confirms that the clamping is complete. Subsequently, the hydraulic cylinder 31 drives the conical guide push rod 32 to retract, or reduces the hydraulic pressure, so that the conical guide push rod 32 maintains a non-load-bearing contact state only with the eccentric positioning hole 63.

[0098] Therefore, during the subsequent grinding process, the tapered guide push rod 32 does not bear the main positioning load, clamping load and grinding load of the workpiece.

[0099] Fifth stage: Grinding with a grinding wheel After the workpiece positioning and clamping status are qualified, the three-axis vertical machining center starts the grinding program. The grinding wheel enters the grinding wheel avoidance through hole 24 from above the positioning support plate 21, and performs trajectory interpolation grinding on the scroll profile and / or scroll bottom surface of the scroll disk 6 according to the preset CNC program.

[0100] During the grinding process, the grinding wheel can perform linear interpolation, circular interpolation, and composite trajectory interpolation in the X and Y directions. The grinding wheel avoids the inner diameter of the through hole 24 and the arrangement of the support block 25 to avoid the effective machining trajectory of the grinding wheel.

[0101] The axial grinding load of the scroll plate 6 is transmitted to the tooling base 1 through the support block 25 and the positioning support plate 21. The horizontal grinding load and cutting torque are resisted by the cylindrical positioning pin 22, the rhomboid positioning pin 23 and the three sets of clamping cylinders 41.

[0102] The three sets of clamping cylinders 41 maintain a clamped state during grinding, preventing the scroll plate 6 from loosening or shifting slightly due to changes in the direction of the grinding wheel's cutting force. The conical guide push rod 32 does not continuously apply top pressure to the hollow cavity of the workpiece, thereby reducing the risk of clamping deformation of the workpiece.

[0103] Phase 6: Grinding wheel retraction, clamping, and part removal After the grinding program is completed, the grinding wheel first exits the grinding wheel clearance through hole 24 and moves to the machine tool's safe position. The grinding wheel safe position detection element sends a safety signal to the oil-gas timing linkage control system.

[0104] After confirming that the grinding wheel has returned to a safe position, the control system controls the three sets of clamping cylinders 41 to retract synchronously, so that the arc-shaped pressure head 43 disengages from the arc-shaped pressure head groove 66 and releases the clamping of the scroll plate 6.

[0105] When necessary, the hydraulic cylinder 31 can control the conical guide push rod 32 to descend slowly, so that the finished scroll plate 6 can fall back smoothly to the support and protection plate 5; or the scroll plate 6 can be disengaged from the cylindrical positioning pin 22 and the rhomboid positioning pin 23 and fall to the support and protection plate 5 through a special unloading mechanism.

[0106] The finished scroll plate 6 is finally supported by the support and protective plate 5. The operator removes the scroll plate 6 from the front opening or the top operating area of ​​the tooling base 1, completing one processing cycle.

[0107] Example 3: Main Parameters The following parameters can be used for each structure in this embodiment: 1. The tooling base 1 has an external dimension of 450mm×450mm and a thickness of 57mm. It is made of 42CrMo alloy steel and is integrally machined and subjected to heat treatment to relieve stress. 2. The positioning support plate 21 has a thickness of 20mm and is made of 42CrMo quenched and tempered steel. The flatness of its positioning reference surface is no greater than 0.005mm. 3. The diameter of the grinding wheel clearance through hole 24 is 280mm; 4. The cylindrical locating pin 22 and the rhomboid locating pin 23 are made of SKD11 material, with a quenching hardness of HRC62~65, and are fitted with the Φ6H6 reference hole 62. 5. The cone angle of the tapered guide surface 33 is 20°, and the surface roughness is not greater than Ra0.8μm; 6. The rated thrust of hydraulic cylinder 31 is 100N, and the maximum output thrust is no more than 120N; 7. The rising speed of the conical guide push rod 32 is 8 mm / s; 8. Three sets of clamping cylinders 41 are arranged at 120° intervals along the circumference, with a standard working air pressure of 0.5MPa and an adjustable range of 0.3~0.8MPa; 9. The arc-shaped pressure head 43 is made of polyurethane material; 10. The supporting protective plate 5 is made of PA66 engineering plastic and is fixedly installed in the protective plate groove 12.

[0108] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A tooling for final grinding of hollow cast iron scroll disks, characterized in that: It includes a tooling base (1), a positioning support unit (2), a pre-guided feeding unit (3), and a circumferential clamping unit (4); The tooling base (1) is a hollow square structure with openings at the top and front. The bottom of the inner cavity of the tooling base (1) is provided with an installation cavity (11) for installing the pre-guided feeding unit (3). The positioning support unit (2) is located on the top of the tooling base (1) and includes a positioning support plate (21), a cylindrical positioning pin (22) and a rhombic positioning pin (23). The positioning support plate (21) is used to support the top plane (61) of the vortex disk (6). The middle part of the positioning support plate (21) is provided with a grinding wheel clearance through hole (24) for the grinding wheel to pass through. The cylindrical positioning pin (22) and the rhombic positioning pin (23) are located at the bottom of the inner wall of the grinding wheel clearance through hole (24). The cylindrical positioning pin (22) and the rhombic positioning pin (23) respectively cooperate with the two reference holes (62) on the top of the vortex disk (6) to restrict the translation and rotation of the vortex disk (6) in the horizontal plane, and together with the positioning support plate (21) restrict the six degrees of freedom of the vortex disk (6). The pre-guided feeding unit (3) includes a hydraulic cylinder (31) disposed in the mounting cavity (11) and a conical guide push rod (32) connected to the output end of the hydraulic cylinder (31). The conical guide push rod (32) matches the eccentric positioning hole (63) at the bottom of the scroll plate (6) and is used to perform center correction and pre-guide the scroll plate (6) after it is placed in place. The circumferential clamping unit (4) includes at least three sets of clamping cylinders (41) arranged circumferentially along the tooling base (1). The piston rod (42) of each clamping cylinder (41) is arranged facing the top of the tooling, and the end of the piston rod (42) is provided with a pressure head (43) for pressing against the bottom of the outer edge of the scroll plate (6).

2. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The grinding wheel clearance through hole (24) matches the outer diameter of the vortex disk (6). The inner wall of the grinding wheel clearance through hole (24) has three support blocks (25) arranged in a ring. The bottom of the two support blocks (25) is provided with a cylindrical positioning pin (22) and a rhomboid positioning pin (23) extending toward the vortex disk (6).

3. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The bottom of the inner cavity of the tooling base (1) is provided with a protective plate groove (12) for installing the support protective plate (5). The middle part of the support protective plate (5) is provided with a push rod clearance hole (51) that matches the inner diameter of the mounting cavity (11). The rear end of the top of the support protective plate (5) is provided with a limiting post (52).

4. The tooling for final grinding of hollow cast iron scroll disks according to claim 3, characterized in that, The tooling base (1) is an integrally machined 42CrMo alloy steel base; the supporting protective plate (5) is made of PA66 engineering plastic.

5. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The inner wall of the grinding wheel clearance through hole (24) is provided with a clamping block (26) and a positioning block (27) that match the clamping groove (64) and positioning groove (65) on the outer wall of the vortex disk (6).

6. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The top of the conical guide push rod (32) is provided with a conical guide surface (33), the cone angle of the conical guide surface (33) is 20°, the conical guide surface (33) is polished, and is used to contact the hole edge of the eccentric positioning hole (63) at the bottom of the scroll plate (6) and to perform radial correction on the scroll plate (6).

7. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The clamping cylinders (41) are configured in three groups, and the three groups of clamping cylinders (41) are evenly arranged at 120° intervals along the circumference of the tooling base (1); the pressure head (43) is made of polyurethane material, and the pressure head (43) is matched with the pressure head groove (66) at the bottom of the outer edge of the scroll plate (6).

8. The tooling for final grinding of hollow cast iron scroll disks according to claim 1, characterized in that, The hydraulic cylinder (31) and the clamping cylinder (41) are respectively connected to the oil-gas timing linkage control system, which is used to control the position detection, pre-guidance, positioning, clamping, loosening and picking up of the scroll plate (6) after grinding according to the preset timing. The oil-gas timing linkage control system is connected to the machine tool CNC system and is equipped with workpiece position detection signal, clamping pressure detection signal and grinding wheel safety position detection signal. When the workpiece is not detected to be in place or the clamping pressure does not reach the set value, the machine tool CNC system prohibits the start of the grinding program.

9. A method for final grinding of a hollow cast iron scroll disk using the tooling described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Fully retract the hydraulic cylinder (31) and keep the support plate (5) in a fixed state, and place the scroll plate (6) to be processed on the support plate (5); S2. After the vortex disk (6) is placed in place, start the hydraulic cylinder (31) to make the conical guide push rod (32) rise at low speed. The vortex disk (6) performs radial correction under the action of the conical guide surface (33) and rises axially to the positioning position of the positioning support unit (2). S3. Continue to raise the conical guide push rod (32) at low speed, so that the cylindrical positioning pin (22) and the rhomboid positioning pin (23) enter the two reference holes (62) of the scroll plate (6) respectively, and make the scroll top plane (61) of the scroll plate (6) fit with the positioning support surface of the three support blocks (25) to complete the positioning of one side and two pins. S4. Start the three sets of clamping cylinders (41) so that the pressure head (43) presses against the pressure head groove (66) at the bottom of the outer edge of the scroll plate (6) in a synchronous manner to complete the circumferential clamping of the scroll plate (6); S5. After confirming that the positioning is completed and the clamping pressure reaches the set value, start the three-axis vertical machining center and use the grinding wheel to pass through the grinding wheel avoidance through hole (24) to perform CNC trajectory grinding on the volute profile and / or the bottom surface of the volute disk (6). S6. After grinding is completed, the grinding wheel is returned to the safe position; the conical guide push rod (32) is raised to the workpiece receiving position. After confirming that the conical guide push rod (32) has reliably received the scroll plate (6), the three sets of clamping cylinders (41) are controlled to retract synchronously; then the conical guide push rod (32) is lowered at a low speed to place the scroll plate (6) stably on the support protective plate (5), and then the operator removes the finished scroll plate (6).

10. The processing method according to claim 9, characterized in that, In steps S2 and S3, the thrust applied by the hydraulic cylinder (31) to the scroll plate (6) is no greater than 120 N; after clamping is completed in step S4, the conical guide push rod (32) retracts or only maintains a non-load-bearing contact state with the scroll plate (6) to reduce the risk of deformation of the hollow cavity of the scroll plate (6) due to continuous concentrated force.

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