Linear cutting tool and method for tiny rectangular groove in outer contour of liquid rocket engine nozzle

Abstract

The invention provides a linear cutting tool and method for a tiny rectangular groove in the outer contour of a liquid rocket engine nozzle. The tool is of a cuboid structure and comprises a round hole, positioning teeth and a fastener. The round hole is formed in the cuboid structure, a gap between the round hole and a to-be-machined outer circle of the nozzle rectangular groove is not smaller than 2 mm, positioning teeth are arranged in the round hole, the positioning teeth and a non-machined part of the nozzle rectangular groove are positioned in a matched mode, and the fastener is used for installing the nozzle into the round hole and fixing the nozzle after the nozzle is matched with the positioning teeth. According to the linear cutting tool and method for the tiny rectangular groove of the engine nozzle, compared with traditional numerical control milling machining, the tool cost is greatly reduced, deburring treatment is not needed after machining, and the total cost is only 10%-20% of the numerical control milling machining.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical manufacturing, and relates to an efficient and low-cost processing technology for micro-rectangular grooves on the outer contour of a nozzle made of difficult-to-machine materials for a liquid rocket engine. Background Art

[0002] The nozzle is a precision injection element that affects the combustion efficiency and stability of a liquid rocket engine. Some are made of difficult-to-machine materials such as superalloys, and have a micro-circular array rectangular groove structure (groove width ≤ 1 mm) on the outer contour. When using numerical control milling for processing, the tool wear is serious and the cost is high. The slow wire electrical discharge machining technology is an effective technical means to achieve precision machining of micro-groove products made of difficult-to-machine materials, but it is generally used for machining rectangular grooves on the inner contour or end face of products. Because when machining rectangular grooves on the outer contour, due to the interference between the clamping fixture and the cutting trajectory, multiple clamping operations are required, the machining is cumbersome and the accuracy is poor. The precision and efficient cutting of rectangular grooves on the outer contour is a machining technical problem in the mechanical manufacturing industry, which limits the application of this technology in the machining of micro-rectangular groove products on the outer contour. Summary of the Invention

[0003] The technical problem solved by the present invention is: aiming at the problems of large tool wear and high cost in the numerical control milling of micro-rectangular grooves (groove width ≤ 1 mm) on the outer contour of a nozzle made of difficult-to-machine materials for a liquid rocket engine, the slow wire electrical discharge machining technology is adopted, and a self-centering square groove cutting tooling is used in cooperation. The machining of rectangular grooves on the outer contour is realized in one clamping, greatly reducing the machining cost of micro-rectangular groove nozzles made of such difficult-to-machine materials, improving the machining efficiency, and achieving burr-free machining, which is suitable for large-scale production and has significant economic benefits.

[0004] The technical solution adopted by the present invention to solve the problem is: a wire cutting tooling for micro-rectangular grooves on the outer contour of a liquid rocket engine nozzle. The tooling is of a cuboid structure and includes a round hole, positioning teeth, threaded holes and fasteners;

[0005] The round hole is arranged on the cuboid structure. The clearance between the round hole and the outer circle of the nozzle rectangular groove to be machined is not less than 2 mm. Positioning teeth are arranged in the round hole, and the positioning teeth are used for positioning in cooperation with the non-machined part of the nozzle rectangular groove. The fasteners are used to fix the nozzle to be machined.

[0006] Preferably, there are generally 3 positioning teeth in the round hole. The clearance between the positioning teeth and the non-machined part of the nozzle rectangular groove is between 0.003 and 0.008 mm, which facilitates the loading and unloading of parts while achieving high-precision self-centering of the nozzle.

[0007] Preferably, the tooth width of the positioning teeth is at least 0.1 mm narrower than the width of the non-machined part between adjacent rectangular grooves to ensure that the positioning teeth will not be machined by electrical discharge.

[0008] Preferably, the fasteners are copper screws.

[0009] Preferably, the fastener avoids the positioning teeth from the side of the cuboid structure to fix the nozzle to be processed and the tooling.

[0010] Preferably, the cuboid structure and its positioning teeth are made of rust-resistant materials, including stainless steel or titanium alloy.

[0011] A method for wire cutting of a micro-rectangular groove on the outer contour of a liquid rocket engine nozzle, comprising:

[0012] Fix the self-centering square groove cutting tooling on the machine tool crossbeam, level and fix it by dial indicator.

[0013] Place the nozzle to be processed into the circular hole of the tooling and fix it with fasteners.

[0014] Use the three-point centering function of the wire electrical discharge machining machine to center the outer circle of the nozzle and determine the origin of the workpiece coordinate system.

[0015] Divide the integral ring rectangular groove into multiple parts with the positioning teeth and fasteners as the boundaries; during the cutting process, after each part of the rectangular groove is cut, automatically cut the wire and re-thread it to process the next part of the rectangular groove until all the rectangular grooves are processed.

[0016] Preferably, during batch processing, when the outer diameter of the nozzle rectangular groove to be processed is kept consistent, after replacing the nozzle, there is no need to center again, and the program can be directly run for processing.

[0017] The beneficial effects of the present invention compared with the prior art are as follows:

[0018] (1) Low processing cost. For the processing of micro-rectangular grooves (groove width ≤ 1 mm) on the outer contour of nozzles made of difficult-to-machine materials, the wire cutting tooling and method for micro-rectangular grooves of an engine nozzle designed by the present invention can greatly reduce the tool cost compared with traditional CNC milling, and there is no need for deburring treatment after processing. The overall cost is only 10% - 20% of that of CNC milling.

[0019] (2) High processing efficiency. Using the self-centering square groove cutting tooling, all rectangular grooves can be processed in one clamping, without multiple clamps, with high automation and high processing efficiency.

[0020] (3) Simple processing process, suitable for mass production. After each part replacement, there is no need to align the part and center it, greatly reducing the process preparation time such as part clamping alignment and tool setting, and being suitable for batch production. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of nozzle processing according to the present invention

[0022] Figure 2 It is a schematic diagram of the rectangular groove on the outer contour of the nozzle according to the present invention;

[0023] Figure 3 Schematic structural diagram of the self-centering square groove wire cutting tooling of the present invention;

[0024] Figure 4 Schematic diagram of the programmed cutting trajectory of the present invention. Specific embodiments

[0025] The present invention will be further described below in conjunction with embodiments.

[0026] The self-centering square groove cutting tooling 2 has a cuboid structure and is generally made of corrosion-resistant materials such as stainless steel or titanium alloy.

[0027] There are 3 positioning teeth 22 in the circular hole 21 of the self-centering square groove cutting tooling, and the teeth are matched with the non-machined part 12 of the nozzle rectangular groove, and the matching clearance ≤ 0.008 mm.

[0028] For the 3 positioning teeth of the self-centering square groove cutting tooling, the tooth width 22 is at least 0.1 mm narrower than the width 12 of the non-machined part between adjacent rectangular grooves.

[0029] The side of the circular hole of the self-centering square groove cutting tooling is provided with an M2 threaded hole 23, and the fastener 24 is used to fix the precision nozzle to the tooling from the side of the cuboid structure while avoiding the positioning teeth.

[0030] A wire cutting processing method for a micro rectangular groove of a liquid rocket engine nozzle, the steps of the method include:

[0031] (1) Fix the self-centering square groove cutting tooling 2 on the machine tool crossbeam, level and fix it by dial indicator;

[0032] (2) Install the nozzle 1 to be processed into the circular hole of the tooling and fix it with the fastener 24;

[0033] (3) Use the three-point centering function of the wire cut EDM machine to center on the outer circle of the nozzle 1 to determine the origin of the workpiece coordinate system;

[0034] (4) Divide the integral ring rectangular groove into 4 parts with 3 positioning teeth 22 and the fastener 24 as the boundaries, and compile 4 sub-programs 31, 32, 33, 34.

[0035] (5) When running the program for cutting, after cutting a part of the rectangular groove 31, automatically cut the wire and re-thread the wire to process the next part of the rectangular groove 32 until all the rectangular grooves are processed;

[0036] (6) During batch processing, after replacing the parts, there is no need to center again, and the program can be directly run for processing.

[0037] Example:

[0038] The self-centering square groove cutting tooling 2 has a block structure and is made of stainless steel.

[0039] The self-centering square groove cutting tooling has a circular hole 21 in the middle, and the clearance between the circular hole and the outer circle 12 of the nozzle rectangular groove to be machined is 3 mm.

[0040] There are 3 positioning teeth 22 in the circular hole 21 of the self-centering square groove cutting tooling, and the teeth are matched with the non-machined part 12 of the nozzle rectangular groove, and the matching clearance is 0.005 mm.

[0041] The widths of the 3 positioning teeth of the self-centering square groove cutting tooling are 0.2 mm narrower than the width of the non-machined part between adjacent rectangular grooves 12.

[0042] The side of the circular hole of the self-centering square groove cutting tooling is provided with an M2 threaded hole 23, and the nozzle is fixed to the tooling by using a copper screw 24.

[0043] A wire cutting method for micro rectangular grooves of a liquid rocket engine nozzle, the steps of the method include:

[0044] (1) Fix the self-centering square groove cutting tooling 2 on the machine tool crossbeam, use a dial indicator to align and fix it;

[0045] (2) Install the nozzle 1 to be machined into the circular hole of the tooling and fix it with a copper screw 24;

[0046] (3) Use the three-point centering function of the wire cut electric discharge machine tool to center on the outer circle of the nozzle 1 to determine the origin of the workpiece coordinate system;

[0047] (4) Divide the integral ring rectangular groove into 4 parts with 3 positioning teeth 22 and the screw 24 as the boundaries, and compile a machining program including cutting diagrams 31, 32, 33, and 34.

[0048] (5) When running the program for cutting, after cutting a part of the rectangular groove 31, automatically cut the wire and re-thread the wire to machine the next part of the rectangular groove 32 until all the rectangular grooves are machined;

[0049] (6) During batch processing, after replacing the parts, there is no need to center again, and the program can be directly run for machining.

[0050] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention all fall within the protection scope of the technical solution of the present invention.

Claims

1. A tool for cutting tiny rectangular grooves on the outer contour of a liquid rocket engine nozzle, characterized in that: The tooling is a rectangular parallelepiped structure, including a circular hole, a positioning tooth and a fastener; The circular hole is arranged on the rectangular structure, and the gap between the circular hole and the outer circle to be processed of the nozzle rectangular groove is not less than 2mm. Positioning teeth are arranged in the circular hole, and the positioning teeth cooperate with the non-processed part of the nozzle rectangular groove for positioning. The fastener is used to install the nozzle into the circular hole and fix it after cooperating with the positioning teeth.

2. The tooling according to claim 1, characterized in that: The matching clearance between the positioning teeth and the non-processed part of the nozzle rectangular groove is between 0.003 and 0.008 mm.

3. The tooling according to claim 1, characterized in that: The tooth width of the positioning teeth is at least 0.1 mm narrower than the width of the non-processed portion between adjacent rectangular grooves.

4. The tooling according to claim 1, characterized in that: The fastener is a copper screw.

5. The tooling according to claim 1, characterized in that: The fastener avoids the positioning teeth from the side of the rectangular structure to achieve the fixation of the nozzle to be processed and the tooling.

6. The tooling according to claim 1, characterized in that: The rectangular structure and its positioning teeth are made of corrosion-resistant materials, including stainless steel or titanium alloy.

7. A method for wire cutting of tiny rectangular grooves on the outer contour of a liquid rocket engine nozzle, characterized in that include: Fix the self-centering square groove cutting tool described in claim 1 to the crossbeam of the machine tool, align it by dialing and fix it; Install the nozzle to be processed into the circular hole of the tooling and fix it with fasteners; Use the three-point centering function of the EDM wire cutting machine to find the center of the nozzle outer circle and determine the origin of the workpiece coordinate system; The entire rectangular groove is divided into multiple parts with the positioning teeth and the fasteners as the boundaries; during the cutting process, after each part of the rectangular groove is cut, the wire is automatically cut and the wire is re-threaded to process the next part of the rectangular groove until all the rectangular grooves are processed.

8. The method according to claim 7, characterized in that: During batch processing, after replacing the nozzle to be processed, there is no need to find the center again, and the program can be run directly for processing.

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