Multifunctional micro-metering hole EDM fixture

Abstract

The invention discloses a multifunctional electrospark machining fixture for fine metering holes, which comprises: a base, a clamping block I and a clamping block II; a variable diameter hole is provided at the center of the base, in which the diameter of the upper hole is smaller than the diameter of the lower hole; a positioning shaft I is provided at the bottom of the clamping block I, the diameter of the positioning shaft I matches the diameter of the upper hole, an eccentric sliding valve installation groove is provided at the top of the clamping block I, and the sliding valve to be processed is installed in the sliding valve installation groove; a positioning shaft II is provided at the bottom of the clamping block II, the diameter of the positioning shaft II matches the diameter of the upper hole, an eccentric valve block installation groove is provided at the top of the clamping block I, and the valve block to be processed is installed in the valve block installation groove; when the clamp is used to process the sliding valve, the clamping block I is installed on the base, and the sliding valve is installed in the clamping block I; when the valve block is processed, the clamping block II is installed on the base, and the valve block is installed in the clamping block II. The fixture assembly of the invention has a simple structure, is fast for the operator to clamp, has strong processability, reasonably limits the degree of freedom of part processing, and is easy to ensure the dimensional accuracy of the parts.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing and relates to a multifunctional electrospark processing fixture for micro-metering holes. Background Art

[0002] The new generation of armored assault equipment power systems represented by the high power density of fourth-generation tanks and high-speed amphibious diesel engines are the core of my country's future army weapons and equipment. They have the typical characteristics of high power density, high mobility in all areas, large flow, and ultra-short injection duration. With the gradual improvement of my country's army equipment level, it is an inevitable requirement for the new generation of armored assault equipment power systems to choose a high-pressure common rail fuel supply system. An important indicator that affects the performance of the injector in this system is the response time of the core key component, the slide valve pair, to the solenoid valve. The solenoid valve cannot directly control the opening and closing of the needle valve pair. The opening and closing of the needle valve is controlled by the slide valve pair. The ratio of the flow rate of the inlet and outlet metering holes of the slide valve pair determines the opening and closing rate of the needle valve. Therefore, the manufacturing technology of the slide valve pair is the key to improving the basic process capabilities. The slide valve pair is composed of Figure 1 The slide valve, slide valve sleeve and Figure 2 The valve block shown in the figure is mainly used to drive the needle valve pair to complete fuel injection under the drive of the solenoid valve according to the ECU command. Among them, the poor consistency of the machining accuracy of the two parts, the slide valve inlet / leakage hole and the valve block inlet / leakage hole, leads to poor consistency of the slide valve pair inlet / leakage ratio, which is one of the main influencing factors. The machining accuracy consistency of the slide valve pair inlet / leakage hole includes two comprehensive indicators: the consistency of the diameter of the micro-metering hole (hereinafter referred to as micro-hole) and the related related dimensions (hereinafter referred to as dimensions) of the slide valve and valve block (hereinafter referred to as valve parts). In actual production, our factory is relatively weak in the precision machining technology of micro-holes of high-hardness materials for valve parts. Traditional needle valve body machining technology and experience have no reference for high-precision micro-hole machining of valve parts (slide valve material 9CrWMn tool steel, hardness requirement 62~65HRC; valve block material W6Mo5Cr4V2 alloy steel, hardness requirement 62~66HRC).

[0003] Most domestic manufacturers have two main solutions for micro-hole processing of parts:

[0004] The first is drilling. This technology is further divided into two processes: ordinary high-speed drilling and micro-hole processing by high-precision machine tools with ultrasonic vibration. The ordinary high-speed drilling technology has many defects: 1. The micro-holes are processed before heat treatment, and the micro-holes are easy to change after heat treatment, and the amount of change is not fixed; 2. The processing accuracy is low and the size consistency is poor; 3. The diameter of the micro-holes processed by high-speed drilling is generally between φ0.15mm and φ0.50mm, and the drill bit is thin and easy to break. The second processing technology has the advantage of strong micro-hole consistency, and the defects are: 1. The micro-holes are processed before heat treatment, and the micro-holes are easy to change after heat treatment, and the amount of change is not fixed; 2. High-frequency ultrasonic vibration produces mechanical processing stress, which affects the accuracy of the machine tool worktable. The drill bit is easy to break due to the rebound force of ultrasonic vibration. The drill bit used in this process costs 1,200 yuan each, and the production cost is high.

[0005] The second is electric spark drilling, which has the advantages of no machining stress, high precision, no burrs, and avoiding heat treatment deformation.

[0006] The drilling process is done by electric sparks, and the fixture used in the process is the clamping system configured on the electric spark machine itself. Figure 3 As shown in the figure, the machine tool fixture structure consists of a spring and a φ5.5mm spindle. The spring is fixed to the upper end of the rotary table with an M3 set screw to clamp it; the φ5.5mm spindle is fixed to the center of the rotary table with an M5 set screw to position it.

[0007] Processing principle: Figure 4 The hole in the needle valve body is fixed with a φ5.5mm mandrel, and the spring clamps the needle valve body shoulder. Input the angle, quantity, and distance between the guide electrode wire and the nozzle hole on the work panel, and then issue a command for the machine to start processing the nozzle hole. The needle valve body is rotated by the rotary table so that the angle between the nozzle hole and the rotation center of the electrode wire meets the angle of 77.5°±1° specified in the product drawing. The operator adjusts the machine guide to find the coordinate position (processing distance) of the nozzle entrance from the fixture rotation center, and uses the electrode wire to rotate at a uniform speed to process the nozzle hole by progressive electro-erosion.

[0008] Our factory uses existing EDM equipment to carry out micro-hole processing of valve parts. We can innovate the ultra-precision processing technology of micro-holes of valve parts and understand the technical mechanism of EDM micro-holes, which is an important guarantee for breaking through the key technology of improving the flow ratio of the inlet / drain holes of sliding valve parts.

[0009] The clamping system of the EDM drilling machine is a rigid configuration specially designed for machine tools, and its defects are as follows:

[0010] 1. Adapt to a single product: Figure 3 As shown, the existing clamping structure of the machine tool is only for the needle valve body part, and the type of processed products is single; there is no interchangeable clamping tooling, and it cannot meet the processing needs of other types of parts with different needle valve body structures.

[0011] 2. The processing quality is poorly stable, and the coincidence between the micro-hole of the part and the processing center of the electrode wire is poor: the positioning element of the machine tool fixture is a φ5.5 (+0.01 / 0) mm mandrel (hereinafter referred to as the mandrel), and the center hole of the needle valve body is the positioning reference, with a size between φ5.6mm and φ5.9mm. The large dispersion of the positioning size of the part causes uncertainty in the size of the gap with the mandrel. The positioning reference error during processing causes the center of the center hole to deviate from the center of the guide electrode wire. When the worktable under the machine tool rotates, the distance between the processing point of the needle valve body and the center of the guide electrode wire is different, and there are slight differences in the discharge time and pulse voltage, which makes the nozzle hole size out of tolerance, the nozzle holes are unevenly distributed, and the angle out of tolerance. Summary of the invention

[0012] (I) Purpose of the invention

[0013] The purpose of the present invention is to provide an accurate, fast and multifunctional micro-metering hole electrospark machining fixture to achieve the purpose of quickly and accurately machining micro-holes of valve parts with different structural sizes and ensuring the size.

[0014] (II) Technical solution

[0015] In order to solve the above technical problems, the present invention provides a multifunctional fine metering hole electrospark machining fixture, which includes: a base 1, a clamping block I2 and a clamping block II3; a reducing hole is opened in the center of the base 1, and the diameter of the upper hole in the reducing hole is smaller than the diameter of the lower hole; a positioning shaft I is arranged at the bottom of the clamping block I2, and the diameter of the positioning shaft I matches the diameter of the upper hole; an eccentric sliding valve mounting groove is arranged on the upper part of the clamping block I2, and the sliding valve to be processed is installed in the sliding valve mounting groove; a positioning shaft II is arranged at the bottom of the clamping block II3, and the diameter of the positioning shaft II matches the diameter of the upper hole; an eccentric valve block mounting groove is arranged on the upper part of the clamping block I2, and the valve block to be processed is installed in the valve block mounting groove; when using the fixture to process the sliding valve, the clamping block I2 is installed on the base 1, and the sliding valve is installed in the clamping block I2; when processing the valve block, the clamping block II3 is installed on the base 1, and the valve block is installed in the clamping block II3.

[0016] Among them, a positioning pin hole is radially opened on the side wall of the sliding valve installation groove of the clamping block I2, and the positioning pin hole is coaxially aligned with the pin hole on the sliding valve to be processed, and the positioning pin 3 is inserted to position the sliding valve to be processed.

[0017] Among them, a processing hole is opened at the bottom of the sliding valve installation groove of the clamping block I2, and the processing hole is located on the central axis of the clamping block I2 and is used to process holes at different positions on the sliding valve.

[0018] A positioning hole is radially opened on the side wall of the valve block installation groove of the clamping block II3, and a fixing block is installed in the positioning hole. The end face of the fixing block is pressed against the side wall of the valve block to limit the valve block.

[0019] Wherein, the base 1 is made of 18Cr2Ni4WA and heat treated at ≥60~64HRC.

[0020] Wherein, the clamping block II3 is made of Cr15 and heat treated at 54-58HRC.

[0021] Wherein, the clamping block I2 is made of Cr15 and heat treated at 54-58HRC.

[0022] Wherein, the fixing block is made of Cr2 and heat treated at 60-64HRC.

[0023] (III) Beneficial effects

[0024] The multifunctional micro-metering hole electrospark machining fixture provided by the above technical solution has the following beneficial effects:

[0025] 1. Fix the guide positioning system of the upper worktable of the machine tool: add a component base to connect the machine tool positioning element spindle, the base aperture is φ5.5 (+0.02 / +0.015) mm, the base and the spindle are precisely matched, the positioning reference error is eliminated during processing, the center of the part processing hole coincides with the center of the electrode wire, and the problem of center deviation of the guide positioning system is solved.

[0026] 2. Fixed processing zero point and processing distance: When processing different valve parts, quickly replace the corresponding clamping blocks. After assembly, the component size is the same as the predetermined processing distance of the machine tool. It only takes 1 minute to replace the fixture.

[0027] 3. Good consistency of part size: The fixture assembly is designed with a simple structure, the operator can clamp quickly, the processability is strong, the freedom of part processing is reasonably limited, the part size accuracy is easy to guarantee, and the product qualification rate is 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 -Simplified diagram of a slide valve in the prior art.

[0029] Figure 2 -Simplified diagram of valve block in the prior art.

[0030] Figure 3 -Simplified diagram of the fixture structure in the prior art.

[0031] Figure 4 -Simplified diagram of a needle valve body in the prior art.

[0032] Figure 5 -Simplified diagram of the fixture structure of the present invention. Figure A and Figure B are two different test objects.

[0033] Figure 6 -Simplified diagram of the base.

[0034] Figure 7 -Simplified diagram of clamping block II.

[0035] Figure 8 -Simplified diagram of clamping block I.

[0036] Fig. 9 -Fixed block diagram.

[0037] Fig.10 -Simplified diagram of fixture installation. DETAILED DESCRIPTION

[0038] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0039] Reference Figures 5 to 10 As shown, the clamp of the present invention comprises: a base 1, a clamping block I2 and a clamping block II3; a reducing hole is opened at the center of the base 1, in which the diameter of the upper hole is smaller than the diameter of the lower hole; a positioning shaft I is arranged at the bottom of the clamping block I2, the diameter of the positioning shaft I matches the diameter of the upper hole, an eccentric sliding valve mounting groove is arranged at the top of the clamping block I2, and the sliding valve to be processed is installed in the sliding valve mounting groove; a positioning shaft II is arranged at the bottom of the clamping block II3, the diameter of the positioning shaft II matches the diameter of the upper hole, an eccentric valve block mounting groove is arranged at the top of the clamping block I2, and the valve block to be processed is installed in the valve block mounting groove; when the clamp is used to process the sliding valve, the clamping block I2 is installed on the base 1, and the sliding valve is installed in the clamping block I2, and when the valve block is processed, the clamping block II3 is installed on the base 1, and the valve block is installed in the clamping block II3.

[0040] A positioning pin hole is radially provided on the side wall of the slide valve installation groove of the clamping block 12. The positioning pin hole is coaxially aligned with the pin hole on the slide valve to be processed, and the positioning pin 3 is inserted to position the slide valve to be processed.

[0041] A processing hole is provided at the bottom of the slide valve installation groove of the clamping block I2. The processing hole is located on the central axis of the clamping block I2 and is used to process holes at different positions on the slide valve.

[0042] A positioning hole is radially provided on the side wall of the valve block installation groove of the clamping block II3, and a fixing block is installed in the positioning hole. The end face of the fixing block is pressed against the side wall of the valve block to limit the valve block.

[0043] Figure 5 As shown: the fixture of the present invention is a manually adjusted combined structure, which can process valve parts with different structures, achieve the purpose of fast and accurate processing, improve positioning accuracy, and enhance product quality.

[0044] Fig.10 As shown: the base is a positioning element, with a precise clearance fit with the spindle, and the spring presses the upper end face of the base. The clamping block is a clamping element, with a small outer circle and a clearance fit with the φ5 hole of the base. In the clamping block, the parts are clamped by a fixing pin (or fixing block), which plays a fixing and clamping role.

[0045] Base processing precision parameters: material 18Cr2Ni4WA; heat treatment ≥60~64HRC; processing machine tools include turning center, CNC gun drilling machine, high-precision CNC internal grinder, high-precision external grinder, high-precision CNC surface grinder; verticality is φ0.01; coaxiality is φ0.01, runout is 0.04, and surface roughness is 0.4.

[0046] Processing accuracy parameters of clamping block II: material Cr15; heat treatment 54~58HRC; processing machine tools include turning center, vertical machining center, high-precision tool grinder, high-precision CNC cylindrical grinder, high-precision CNC surface grinder; verticality is φ0.01; parallelism is 0.01, and surface roughness is 0.4.

[0047] Processing accuracy parameters of clamping block I: material Cr15; heat treatment 54~58HRC; processing machine tools include turning center, vertical machining center, high-precision tool grinder, high-precision CNC cylindrical grinder, high-precision CNC surface grinder; verticality is φ0.01; parallelism is φ0.01, and surface roughness is 0.4.

[0048] The machining accuracy parameters of the fixed block are: material Cr2; heat treatment 60~64HRC; the machining machine is a vertical machining center and a high-precision CNC surface grinder; the verticality is 0.005; the parallelism is 0.005, and the surface roughness is 0.2.

[0049] Fig.10 As shown: After the machine tool has processed the needle valve body spray hole with a diameter of φ6mm and a processing distance of 52.05mm, the slide valve is processed by EDM with a diameter of φ0.12±0.005 ( Figure 3 ) Micro hole, the base and the mandrel match, the upper bottom end face of the base is close to the machine tool worktable, the spring presses the upper end face of the base, the φ5 hole of the base and the clamping element clamping block II equipped with a slide valve match, and the center of the micro hole and the center of the electrode wire automatically coincide. After adjustment, micro hole processing is carried out according to the existing program of the machine tool.

[0050] When machining the φ0.4 (+0.02 / 0) micro-hole of the valve block, the steps are as follows: First, replace the corresponding specification of carbide wire according to the diameter of the micro-hole to be machined on the part; second, install the clamping element clamping block I into the valve block, insert the horizontal groove of the clamping block I into the fixed block, and the side end face of the fixed block presses the plane of the valve block; third, replace the clamping block, and the center of the micro-hole and the center of the electrode wire automatically coincide. After the adjustment is completed, the micro-hole machining is carried out according to the existing program of the machine tool.

[0051] The nature of the machine tool clamping system of the present invention is changed from rigidity to flexibility and multifunctionality. The structural design of the base and the clamping shaft is reasonable and simple, which eliminates the unfavorable processing conditions caused by the deviation between the center of the micro hole of valve parts and the center of the guide electrode wire due to positioning errors, avoids the related related dimensions of the micro metering holes from exceeding the tolerance, and removes the unfavorable factors of the original clamping system. The operator can replace the product effectively and timely, and the adjustment time required for part processing is shortened from 0.5 hours to 1 minute, saving time and effort. In terms of fixture manufacturing accuracy, the simple processing means and the reasonable use of high-precision machine tools ensure the accuracy of the fixture. It is suitable for the processing of micro metering holes of different positions and diameters of valve parts, and realizes rapid adjustment of machine tool production changes.

[0052] It can be seen from the above technical solution that the present invention has the following significant features:

[0053] 1. The base and the clamping block have a clearance fit, the base hole φ5 (+0.02 / +0.01) mm and the small outer circle of the clamping block φ5±0.005 mm, the fit accuracy is high, the surface roughness of the fit contact surface is 0.4, the processing accuracy is high, the coincidence of the central axis is good, and it is easy to ensure the qualified rate of parts processing.

[0054] 2. The positioning element base that matches the machine tool spindle is unique. When replacing the product, only the corresponding clamping axis needs to be replaced, which realizes the characteristics of rapid production change, fixed processing zero point, and flexible processing.

[0055] 3. The base and the machine tool spindle have high matching accuracy. The φ5.5 (+0.02 / +0.015) mm base hole and the spindle φ5.5 (+0.01 / 0) mm match to form a positioning element. The positioning reference is unified and the matching gap is small, which improves the positioning accuracy of the fixture and achieves the purpose of accurate production.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multifunctional micro-metering hole electrospark machining fixture, characterized in that: include: A base (1), a clamping block I (2) and a clamping block II (3); a reducing hole is provided at the center of the base (1), in which the diameter of the upper hole is smaller than the diameter of the lower hole; a positioning shaft I is provided at the bottom of the clamping block I (2), the diameter of the positioning shaft I matches the diameter of the upper hole, an eccentric sliding valve installation groove is provided at the top of the clamping block I (2), and the sliding valve to be processed is installed in the sliding valve installation groove; a positioning shaft II is provided at the bottom of the clamping block II (3), the diameter of the positioning shaft II matches the diameter of the upper hole, an eccentric valve block installation groove is provided at the top of the clamping block I (2), and the valve block to be processed is installed in the valve block installation groove; when the clamp is used to process the sliding valve, the clamping block I (2) is installed on the base (1), and the sliding valve is installed in the clamping block I (2); when the valve block is processed, the clamping block II (3) is installed on the base (1), and the valve block is installed in the clamping block II (3).

2. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 1, characterized in that: A positioning pin hole is radially provided on the side wall of the slide valve installation groove of the clamping block 1 (2), and the positioning pin hole is coaxially aligned with the pin hole on the slide valve to be processed, and the positioning pin is inserted to position the slide valve to be processed.

3. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 2, characterized in that: A processing hole is provided at the bottom of the slide valve installation groove of the clamping block 1 (2), and the processing hole is located on the central axis of the clamping block 1 (2) and is used to process holes at different positions on the slide valve.

4. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 1, characterized in that: A positioning hole is radially opened on the side wall of the valve block installation groove of the clamping block II (3), and a fixing block is installed in the positioning hole. The end face of the fixing block is pressed tightly against the side wall of the valve block to limit the position of the valve block.

5. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 1, characterized in that: The base (1) is made of 18Cr2Ni4WA and has a heat treatment temperature of ≥60-64HRC.

6. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 1, characterized in that: The clamping block II (3) is made of Cr15 and heat treated to 54-58 HRC.

7. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 1, characterized in that: The clamping block I (2) is made of Cr15 and heat treated to 54-58 HRC.

8. The multifunctional micro-metering hole electrospark machining fixture as claimed in claim 4, characterized in that: The fixing block is made of Cr2 and heat treated at 60-64HRC.

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