Precise grinding tool and method for inner hole of high-hardness material assembly

Abstract

The invention provides a high-hardness material assembly inner hole precision grinding tool and method, the high-hardness material assembly inner hole precision grinding tool comprises a base plate, a balance weight, a positioning assembly and a locking assembly, the base plate is connected with an inner hole grinding machine, alignment is conducted through an alignment belt, one side of the base plate is connected with the balance weight through a screw, and a positioning mandrel is installed on the base plate on the opposite side of the balance weight; the positioning mandrel penetrates through the end face of a seat body of the part and is locked and fixed through a locking assembly, one side, located under a piston cylinder of the part, of the rhombic pin is arranged in a pin hole of the base plate, and the other side of the rhombic pin is arranged in a lower hole of the piston cylinder. The tool is simple in structure, convenient to operate and high in product machining quality. The clamping mode is good in repeatability, only one-time clamping alignment needs to be carried out on the tool, the consistency of workpiece clamping positions is guaranteed through cooperation of a positioning face and a positioning pin subsequently, and efficient machining of batch products is achieved; the center distance of the holes can be guaranteed through a tool and is not affected by manual operation factors.

Description

Technical Field

[0001] The invention belongs to the technical field of precision grinding of inner holes of high-hardness material parts, and in particular relates to a tool and a processing method for precision grinding of inner holes of high-hardness material assembly parts. Background Art

[0002] In the field of aviation and aerospace, high-strength steel and other high-hardness materials are widely used. The high-hardness material seat assembly is a key part of a certain type of aerospace product of our company. The material is 30CrMnSiNi2A. The hardness of the material after quenching can reach 55HRC-60HRC, and its size and shape tolerance requirements are relatively strict. Due to the special process requirements of the product, it is required to process the inner holes on both sides of the piston cylinder parts after the seat body (middle piece) and the piston cylinder (two side pieces) are combined. The diameter tolerance of the hole is not more than 0.03mm, the length is nearly 60mm, and there are half holes in some parts. There is discontinuous cutting during processing, and the roughness of the hole is required to be within Ra0.4. Due to the special structure of the product and the mechanical processing characteristics of high hardness and chip breaking processing, it is urgent to find a suitable process solution to meet the technical index requirements of the product. Summary of the invention

[0003] The technical problem solved by the present invention is to provide a tooling and processing method for precision grinding of inner holes of high-hardness material assemblies, and propose a precision grinding solution for discontinuous deep holes of high-hardness material seat assemblies, solving the problem that conventional processing cannot meet the requirements of product technical indicators.

[0004] The technical solution adopted by the present invention is: a tool for precision grinding of inner holes of high-hardness material assemblies, including a chassis, a counterweight, a positioning assembly, and a locking assembly. The positioning assembly includes a positioning mandrel and a diamond pin for positioning parts. The chassis is a disc structure, and the chassis is connected to an inner hole grinder and aligned by an alignment belt. One side of the chassis is connected to the counterweight by screws, and a positioning mandrel is installed on the chassis on the opposite side of the counterweight. The positioning mandrel passes through the end face of the seat body of the part and is locked and fixed by the locking assembly. The diamond pin is located directly below the piston cylinder of the part, one side is placed in the pin hole of the chassis, and the other side is placed in the hole below the piston cylinder for circumferential positioning of the part and the chassis.

[0005] Preferably, the locking assembly includes an open washer and a nut, the open washer passes through the positioning core shaft, one end face of the open washer is pressed against the end face of the seat body of the part, and the other end face of the open washer is locked by a nut threaded on the positioning core shaft.

[0006] Preferably, it also includes a tool rod used in conjunction with the processing tooling, the tool rod comprising a threaded section, a positioning section, a transition section and a connecting section from left to right, the threaded section of the tool rod being a threaded column connected to the tool holder, the positioning section of the tool rod being a cylinder, the outer circle of which cooperates with the inner hole of the tool holder for positioning, the transition section of the tool rod being a stepped cylinder, a countersunk groove being machined on the side connected to the positioning section, an internal thread being machined on the end face of the connecting section of the tool rod for connection with a grinding wheel, the diameter of the connecting section of the tool rod being adapted to the inner hole diameter of the workpiece, and the grinding wheel being made of 80# white corundum with a hardness type of L.

[0007] Preferably, the counterweight is an arc-shaped protrusion, and the upper surface of the counterweight is trimmed to ensure that the processing tooling reaches a dynamic balance state.

[0008] Preferably, the arbor is made of alloy steel Cr12MoVA with a quenching hardness of 55HRC-60HRC.

[0009] Preferably, the distance between the center of the chassis and the center of the diamond pin is equal to the distance between the centers of the holes of the two piston cylinders of the part.

[0010] Preferably, the part is clearance-fitted with the positioning mandrel and the diamond pin.

[0011] A method for precision grinding the inner hole of a high-hardness material assembly is disclosed. The inner hole of a high-hardness material assembly is machined using the above-mentioned machining tool and tool bar. The assembly includes a seat body and a piston cylinder installed on both sides of the seat body. After the seat body and the piston cylinder are assembled, the inner holes on both sides of the piston cylinder are machined. The specific machining steps are as follows:

[0012] a) Install the processing tooling and align it, and the runout of the alignment belt should not exceed 0.005;

[0013] b) Clamp the parts, press them tightly, and check that the hole runout is no more than 0.05;

[0014] c) Rough grinding: reserve 0.05mm-0.1mm margin for rough grinding; rough grinding parameters: spindle speed: 100r / min; grinding wheel speed: 10000-15000r / min; each feed: 0.03mm-0.05mm;

[0015] d) Fine grinding; spindle speed: 150r / min; grinding wheel speed: 15000r / min-20000r / min; feed per time: 0.005mm-0.01mm;

[0016] e) Parts inspection;

[0017] f) Process the piston cylinder on the other side of the part, rotate the part 180 degrees and press it;

[0018] g) repeat steps c) and d);

[0019] h) Disassemble the parts and blow them clean;

[0020] i) Parts inspection.

[0021] The beneficial effects of the present invention are as follows: the tooling structure of the present invention is simple and easy to operate, and it is suitable for the inner hole processing of this type of seat assembly parts, which solves the problem that the size and roughness of the workpieces in the intermittent processing of turning (milling) do not meet the requirements, and the tool cost is high, and the processing quality of the product is high. The clamping method of the present invention has good repeatability, and only needs to be clamped and aligned once for the tooling, and then the consistency of the workpiece clamping position is ensured by the positioning surface and the positioning pin, so that the efficient processing of batch products can be realized; the center distance of the hole can be guaranteed by the tooling, and is not affected by human operation factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the assembly structure of the tooling for precision grinding of inner holes of high-hardness material assemblies.

[0023] Figure 2 This is the front view of the tooling for precision grinding of inner holes of high-hardness material assemblies.

[0024] Figure 3 Schematic diagram of the tool bar structure.

[0025] Figure markings: 1-counterweight, 2-screw, 3-chassis, 4-positioning spindle, 5-diamond pin, 6-open washer, 7-nut, 8-part, 9-tool bar, 901-threaded section, 902-positioning section, 903-transition section, 904-connecting section. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The present invention is specially designed for the special process requirements of the key parts of a certain type of aerospace products of our company. The material is 30CrMnSiNi2A, and the hardness of the material can reach 55HRC-60HRC after quenching. It requires that the inner holes on both sides of the piston cylinder parts be processed after the seat body (middle piece) and the piston cylinder (two side pieces) are combined. The diameter tolerance of the hole is not more than 0.03mm, the length is nearly 60mm, and there are half holes in some parts. There is discontinuous cutting during processing, and the roughness of the hole is required to be within Ra0.4.

[0028] The main technical problems to be solved include the following two aspects: 1) In view of the particularity of the part structure, it is necessary to design a special tooling fixture that can not only ensure the clamping requirements of the parts, but also meet the eccentricity problem when the tooling rotates with the equipment; 2) Explore the processing plan for grinding high-hardness materials, including the design of the tool bar, the selection of the grinding wheel, the design of the grinding allowance and the grinding parameters.

[0029] like Figure 1 and Figure 2 As shown, a tool for precision grinding of inner holes of high-hardness material assemblies includes a chassis 3, a counterweight 1, a positioning assembly, and a locking assembly. The positioning assembly includes a positioning mandrel 4 and a diamond pin 5 for positioning a part 8. The chassis 3 is a disc structure. The chassis 3 is connected to the inner hole grinder and aligned by an alignment belt. One side of the chassis 3 is connected to the counterweight 1 by a screw 2. The counterweight 1 is an arc-shaped protrusion. The upper surface of the counterweight 1 is trimmed to ensure that the processing tool reaches a dynamic balance state. A positioning mandrel 4 is installed on the chassis 3 on the opposite side of the counterweight 1. The positioning mandrel 4 passes through the end face of the seat body of the part 8 and is locked and fixed by the locking assembly. The locking assembly includes an open washer 6 and a nut 7. The open washer 6 passes through the positioning mandrel 4. One end face of the open washer 6 is pressed against the end face of the seat body of the part 8, and the other end face of the open washer 6 is locked by a nut 7 screwed on the positioning mandrel 4. The diamond pin 5 is located directly below the piston cylinder of the part 8, with one side placed in the pin hole of the chassis 3 and the other side placed in the hole below the piston cylinder for circumferential positioning of the part 8 and the chassis 3. The distance between the center of the chassis 3 and the center of the diamond pin 5 is equal to the distance between the centers of the holes of the two piston cylinders of the part 8.

[0030] The part 8 is clearance-fitted with the positioning mandrel 4 and the diamond pin 5 .

[0031] like Figure 3As shown, it also includes a tool bar 9 used in conjunction with the processing tooling. The tool bar 9 is made of alloy steel Cr12MoVA with a quenching hardness of 55HRC-60HRC. The tool bar 9 is composed of a threaded section 901, a positioning section 902, a transition section 903 and a connecting section 904 from left to right. The threaded section 901 of the tool bar 9 is a threaded column connected to the tool holder. The positioning section 902 of the tool bar 9 is a cylinder, and the outer circle is positioned in conjunction with the inner hole of the tool holder. The transition section 903 of the tool bar 9 is a stepped cylinder, and a recessed groove is machined on the side connected to the positioning section 902. The end face of the connecting section 904 of the tool bar 9 is machined with an internal thread connected to the grinding wheel. The diameter of the connecting section 904 of the tool bar 9 is adapted to the inner hole diameter of the part 8. The selected grinding wheel features are as follows: a) Abrasive type. The abrasive is white corundum material, because white corundum has a relatively high hardness, the abrasive grains are not easy to be blunted, and the cutting performance is good; and the toughness of white corundum is relatively low, and the abrasive grains are easy to break during grinding to form new cutting edges, so the cutting edge is sharper, which can reduce the grinding force and grinding heat. b) Abrasive particle size. Considering the comprehensive processing efficiency and the surface roughness of the workpiece Ra0.8, the particle size of the grinding wheel is selected to be 60#-80#. c) Hardness. When grinding high-hardness steel, the hardness of the grinding wheel should be higher than that of the grinding wheel for grinding carbon steel, so that the abrasive grains fall off and obtain self-sharpening. Generally, the grinding wheel hardness of JN is selected, and the medium-soft K and L are the most commonly used. The present invention finally determined the grinding wheel of white corundum 80# and hardness type L through experimental exploration.

[0032] A method for precision grinding the inner hole of a high-hardness material assembly is disclosed. The inner hole of a high-hardness material assembly is processed by using the above-mentioned processing tooling and tool rod. The assembly includes a seat body and a piston cylinder installed on both sides of the seat body. After the seat body and the piston cylinder are combined, the inner holes on both sides of the piston cylinder are processed. The process includes: design of the tool rod → selection of the grinding wheel → selection of the grinding allowance → design of the grinding parameters.

[0033] The specific processing steps are as follows:

[0034] a) Install the processing tooling and align it, and the runout of the alignment belt should not exceed 0.005;

[0035] b) Clamp part 8, press it tightly, and check that the hole runout is no more than 0.05;

[0036] c) Rough grinding: reserve 0.05mm-0.1mm margin for rough grinding; rough grinding parameters: spindle speed: 100r / min; grinding wheel speed: 10000-15000r / min; each feed: 0.03mm-0.05mm;

[0037] d) Fine grinding; spindle speed: 150r / min; grinding wheel speed: 15000r / min-20000r / min; feed per time: 0.005mm-0.01mm;

[0038] e) Part 8 inspection;

[0039] f) Process the piston cylinder on the other side of part 8, rotate the part 180 degrees and press it tightly;

[0040] g) repeat steps c) and d);

[0041] h) Disassemble and blow clean part 8;

[0042] i) Part 8 inspection.

[0043] The above are specific embodiments of the present invention and the technical principles used. Any modifications and equivalent changes based on the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A tool for precision grinding of inner holes of high-hardness material assemblies, characterized by: It includes a chassis, a counterweight, a positioning assembly, and a locking assembly. The positioning assembly includes a positioning spindle and a diamond pin for positioning parts. The chassis is a disc structure, connected to an inner hole grinder, and aligned through an alignment belt. One side of the chassis is connected to the counterweight by screws, and a positioning spindle is installed on the chassis on the opposite side of the counterweight. The positioning spindle passes through the end face of the seat body of the part and is locked and fixed by the locking assembly. The diamond pin is located directly below the piston cylinder of the part, one side is placed in the pin hole of the chassis, and the other side is placed in the hole below the piston cylinder for circumferential positioning of the part and the chassis.

2. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 1, characterized in that: The locking assembly includes an open washer and a nut. The open washer passes through the positioning core shaft, one end face of the open washer is pressed against the end face of the seat body of the part, and the other end face of the open washer is locked by a nut screwed on the positioning core shaft.

3. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 1, characterized in that: It also includes a tool rod used in conjunction with the processing tooling, the tool rod comprising a threaded section, a positioning section, a transition section and a connecting section from left to right, the threaded section of the tool rod being a threaded column connected to the tool holder, the positioning section of the tool rod being a cylinder, the outer circle of which cooperates with the inner hole of the tool holder for positioning, the transition section of the tool rod being a stepped cylinder, a countersunk groove being machined on the side connected to the positioning section, an internal thread being machined on the end face of the connecting section of the tool rod for connection with a grinding wheel, the diameter of the connecting section of the tool rod being adapted to the inner hole diameter of the workpiece, and the grinding wheel being made of 80# white corundum with a hardness type of L.

4. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 1, characterized in that: The counterweight is an arc-shaped convex block, and the upper surface of the counterweight is trimmed to ensure that the processing tooling reaches a dynamic balance state.

5. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 3 is characterized by: The knife bar is made of alloy steel Cr12MoVA with a quenching hardness of 55HRC-60HRC.

6. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 1, characterized in that: The distance between the center of the chassis and the center of the rhombus pin is equal to the distance between the centers of the holes of the two piston cylinders of the part.

7. The tooling for precision grinding inner holes of high-hardness material assemblies according to claim 1, characterized in that: The parts are clearance-matched with the positioning mandrel and the diamond pin.

8. A method for precision grinding of inner holes of high-hardness material assemblies, characterized in that: The inner hole of a high-hardness material assembly is processed by using the processing tool and the tool rod described in claim 3. The assembly includes a seat body and a piston cylinder installed on both sides of the seat body. After the seat body and the piston cylinder are combined, the inner holes on both sides of the piston cylinder are processed. The specific processing steps are as follows: a) Install the processing tooling and align it, and the runout of the alignment belt should not exceed 0.005; b) Clamp the parts, press them tightly, and check that the hole runout is no more than 0.05; c) Rough grinding: reserve 0.05mm-0.1mm margin for rough grinding; rough grinding parameters: spindle speed: 100r / min; grinding wheel speed: 10000-15000r / min; each feed: 0.03mm-0.05mm; d) Fine grinding; spindle speed: 150r / min; grinding wheel speed: 15000r / min-20000r / min; feed per time: 0.005mm-0.01mm; e) Parts inspection; f) Process the piston cylinder on the other side of the part, rotate the part 180 degrees and press it; g) repeat steps c) and d); h) Disassemble the parts and blow them clean; i) Parts inspection.

Images