Device and technological method for cold and hot press fitting of primary seat assembly

Abstract

The invention relates to the field of machining, in particular to a device and process method for cold and hot press fitting of a first-stage base assembly, the device comprises a first-stage base, a first-stage base clamp and a heating platform, the first-stage base clamp is arranged on the heating platform, the heating platform heats the first-stage base clamp, and a mounting groove is formed in the first-stage base clamp; a mounting groove is formed in the first-stage seat, a clamp positioning pin mounting hole is formed in the mounting groove, a clamp positioning pin is arranged in the clamp positioning pin mounting hole and is in clearance fit with the clamp positioning pin mounting hole, a seat hole is formed in the first-stage seat, and the clamp positioning pin penetrates through the seat hole in the first-stage seat. Stress concentration and the dynamic performance of the electro-hydraulic servo valve in the pressing process of the first-stage seat assembly can be improved, the frequency of repeated disassembly and assembly of the first-stage seat assembly is reduced, the machining cost is reduced, and the one-time assembly and adjustment qualification rate of the servo valve is improved.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing, and in particular to a device and a process method for cold and hot press-fitting a primary seat component. Background Art

[0002] In the jet deflector valve, the first-stage seat assembly is a core component and a key component for controlling the flow rate of the pre-stage. The processing quality of the first-stage seat assembly determines the quality of the servo valve and the qualified rate of the product's one-time assembly and adjustment. The current processing method of the first-stage seat assembly is to use a mechanical method to press the upper and lower pressure blocks of the jet sheet into the first-stage seat through extrusion deformation. The friction of the interference fit surface is completely guaranteed by extrusion deformation. During the mechanical pressing process, the upper and lower pressure blocks will rotate at a certain angle, affecting the symmetry of the first-stage seat assembly, thereby affecting the servo performance. The morphology of the interference fit surface will be destroyed during the rotation, which will cause the servo valve to drift under high temperature conditions. Summary of the invention

[0003] The purpose of the present invention: In order to solve the problems existing in the prior art, the present invention proposes a device and process method for cold and hot pressing of a first-level seat assembly. First, the first-level seat is processed to a fine processing state and the corresponding protrusion amount is matched with the thickness of the upper and lower pressure blocks and the jet sheet. Then the inner hole of the first-level seat is ground to match a certain amount of interference with the upper and lower pressure blocks. The first-level seat is placed on an electric heating platform for heating, and the upper and lower pressure blocks and the jet sheet are placed in a low-temperature cooling solution for insulation. When the heating time of the first-level seat meets the clearance requirements, the upper and lower pressure blocks and the jet sheet are placed in the first-level seat and knocked flat with a wooden stick. The first-level seat assembly is processed by cold and hot pressing to make the original interference fit become a clearance fit. After cooling, the friction of the interference bonding surface is increased according to the elastic deformation to ensure that the deformation stress of the interference bonding surface is reduced. The performance of the servo valve is more stable under high temperature conditions, and the one-time adjustment pass rate of the servo valve is steadily improved.

[0004] The present invention can improve stress concentration during the pressing process of the first-stage seat assembly and the dynamic performance of the electro-hydraulic servo valve, reduce the frequency of repeated disassembly and installation of the first-stage seat assembly, reduce processing costs, and improve the one-time assembly and adjustment qualification rate of the servo valve.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A device for hot and cold pressing a first-level seat assembly comprises a first-level seat, a first-level seat fixture and a heating platform, wherein the first-level seat fixture is arranged on the heating platform, and the heating platform heats the first-level seat fixture, and an installation groove is arranged inside the first-level seat fixture, a fixture locating pin installation hole is arranged in the installation groove, a fixture locating pin is arranged in the fixture locating pin installation hole, and the fixture locating pin and the fixture locating pin installation hole are clearance-matched, a seat hole is arranged on the first-level seat, and the fixture locating pin passes through the seat hole on the first-level seat.

[0007] Furthermore, there are two positioning pins of the fixture, which match the positions and sizes of the two positioning holes on the part assembly.

[0008] Furthermore, the device also includes a wooden pressing head.

[0009] Furthermore, the first-stage seat is fixed in the mounting groove of the first-stage seat fixture by mounting screws, the flatness of the upper and lower surfaces of the first-stage seat is within 0.005, the parallelism of the upper and lower surfaces of the first-stage seat is within 0.005, the seat hole size on the first-stage seat matches the outer circle of the part assembly and satisfies a certain interference fit.

[0010] Furthermore, the first-stage seat fixture is made of a material with a low thermal expansion coefficient and strong heat transfer performance.

[0011] A process method for hot and cold pressing a first-level seat assembly using the device, the method comprising the following steps:

[0012] Step 1: Prepare individual parts of the parts assembly, including an upper pressing block, a lower pressing block, a jet sheet, and two locating pins;

[0013] Step 2: Install the first-level seat fixture on the heating platform, heat the heating platform to T1 temperature, keep it warm for t hours, combine the upper and lower pressing blocks and the jet sheet with process positioning pins to form a parts assembly, and place the parts assembly in a low-temperature cooling solution;

[0014] Step 3: Take the parts assembly out of the low-temperature cooling solution, align the two process positioning pins on the parts assembly with the two fixture positioning pins on the first-stage seat fixture. At this time, the lower pressing block is located above the jet sheet, and the upper pressing block is located below the jet sheet. Tap the lower pressing block on the process positioning pin to make the upper pressing block, jet sheet and lower pressing block slide onto the fixture positioning pin. Continue to tap the lower pressing block to knock the parts assembly into the seat hole of the first-stage seat to form a first-stage seat assembly. At this time, the temperature of the first-stage seat assembly rises to the same temperature as the first-stage seat.

[0015] Step 4: After the first-stage seat assembly cools to room temperature, align the two locating pins prepared in step 1 with the two fixtures for positioning. Use the process press of the vertical drilling machine to press the two locating pins into the two positioning holes of the first-stage seat assembly. At the same time, the two fixture locating pins are squeezed out by the locating pins. Then, use a wooden press to knock the lower pressing block so that the surface of the lower pressing block is flush with the upper surface of the first-stage seat.

[0016] Furthermore, the method further comprises:

[0017] Step 5: Place the first-stage seat assembly under a 30x tool microscope to check whether the symmetry and verticality meet the requirements; Step 6: Perform a pressure test on the first-stage seat assembly that meets the requirements in step 5 on a pressure test bench to ensure that the pressure in the two chambers of the first-stage seat assembly meets the design indicators.

[0018] Furthermore, in step 4, after the first-stage seat assembly is cooled to room temperature, the upper and lower pressing blocks are checked to ensure that they are not allowed to fall off, and the parallelism between the surface of the upper pressing block and the surface of the first-stage seat is measured to ensure that it meets the requirements.

[0019] Further, in step 4, the first-stage seat fixture with the first-stage seat assembly installed is installed on the vise of the vertical drilling machine, and two locating pins are pressed into the two locating holes of the first-stage seat assembly by the process press head. At the same time, the two fixture locating pins are squeezed out by the locating pins.

[0020] Compared with the existing servo valve hydraulic amplifier structure, the present invention has the following advantages:

[0021] The present invention combines the first-level seat components by cold and hot pressing, so that the original interference fit is changed into a clearance fit. After cooling, the friction force of the interference bonding surface is increased according to the elastic deformation, so as to ensure that the deformation stress of the interference bonding surface is reduced. The performance of the servo valve is more stable under high temperature conditions, and the qualified rate of the servo valve in one installation and adjustment is steadily improved. Specifically, it has the following advantages:

[0022] (1) The present invention proposes a process method for cold and hot pressing a first-stage seat assembly, which comprises two parts: one part is to heat the first-stage seat by a heating platform so that the inner hole size becomes larger, but the performance of the overall component is not affected, wherein the heating platform is an electric heating platform; the other part is to place the upper and lower pressing blocks and the jet sheet in a cooling solution with a combination of process positioning pins for cooling, so as to ensure that the outer diameter of the upper and lower pressing blocks becomes smaller, and to use the gap to install the upper and lower pressing blocks and the jet sheet in the first-stage seat assembly.

[0023] (2) The present invention prepares a finely machined first-level seat, grinds both the upper and lower surfaces of the first-level seat flat, ensures that the flatness is within 0.005 and the parallelism is within 0.005, and grinds the seat hole to a certain size to match the outer circle of the upper and lower pressing blocks and meet a certain interference fit. The sizes are matched one by one and marked to prevent confusion in the installation of parts.

[0024] (3) The present invention proposes that the first-stage seat is installed in a first-stage seat fixture and then placed in an electric heating platform for heating. The electric heating platform has a certain heat preservation effect. The first-stage seat is fixed in the fixture with positioning screws, so that the size of the inner hole of the first-stage seat is enlarged within an acceptable range.

[0025] (4) In the present invention, the upper and lower pressing blocks and the jet sheet are combined together by process pins and immersed in a cooling solution to cool down, so that their outer diameter is not affected by the ambient temperature and the size can be reduced to the micron level, making it easier to install the upper and lower pressing blocks and the jet sheet in the seat hole of the first-level seat.

[0026] (5) The device of the present invention is composed of a primary seat fixture, a fixture locating pin, a mounting screw, a process fixture locating pin, a wooden pressure head, etc. The fixture locating pin is installed in the primary seat fixture, has a clearance fit with the mounting hole of the primary seat fixture, and passes through the seat hole of the primary seat, mainly playing the role of positioning and preventing rotation.

[0027] (6) The first-stage seat, fixture positioning pin, and first-stage seat fixture of the present invention are all processed together on an electric heating platform. The first-stage seat fixture is required to be made of a material with a low thermal expansion coefficient and strong heat transfer performance. The low thermal expansion coefficient is to prevent the first-stage seat fixture from expanding and interfering with the position of the first-stage seat.

[0028] (7) The two mounting holes for the clearance mounting fixture locating pins in the first-stage fixture of the present invention are processed by slow-moving machining to ensure the size and position accuracy of the fixture locating pin holes.

[0029] (8) The function of the two fixture locating pins in the first-stage seat fixture of the present invention is to prevent the upper and lower pressure blocks and the jet sheet from rotating when the upper and lower pressure blocks and the jet sheet are installed, and also to guide the installation of the upper and lower pressure blocks and the jet sheet.

[0030] (9) When installing the cooling upper and lower pressure blocks and jet plates, use a wooden pressure head to knock the lower pressure block to ensure that the upper and lower pressure blocks and the jet plate are in contact with the surface of the first-stage seat fixture, and to ensure that the upper and lower pressure blocks are level in the first-stage seat assembly without tilting.

[0031] (10) After installing the upper and lower pressure blocks and the jet sheet, place the first-stage seat assembly in room temperature to cool to normal temperature, and check that the upper and lower pressure blocks are not allowed to fall off. Measure the parallelism between the surface of the lower pressure block and the surface of the first-stage seat. When using process pins to combine the upper and lower pressure blocks, pay attention to the upper pressure block at the bottom and the lower pressure block at the top. The first-stage seat is installed in the first-stage seat positioning block with the word "up" engraved on it and installed downward, facing yourself, to prevent the upper and lower pressure blocks from being pressed in reverse.

[0032] (11) Place the first-stage seat fixture on the vise and use the process press to press out the fixture positioning pin, and press the positioning pin into the positioning holes of the upper and lower pressure blocks.

[0033] (12) Install the first-stage seat assembly in the test bench to test whether the pressures in the two chambers of the first-stage seat assembly are equal, and verify whether there are any problems with the cold and hot press assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a schematic diagram of the process flow of a process method for cold and hot pressing a first-level seat component.

[0035] Figure 2 It is a schematic diagram of the compression structure of the first-stage seat assembly of the present invention.

[0036] Figure 3 It is a schematic diagram of the heating structure of multiple groups of first-stage seats of the present invention.

[0037] Figure 4 It is a schematic diagram of the structure of installing upper and lower pressing blocks and jet sheets of the present invention.

[0038] Figure 5 It is a schematic diagram of the structure of the upper and lower pressing blocks and the jet sheet of the present invention being placed in a low-temperature cooling solution for refrigeration.

[0039] Figure 6 It is a schematic diagram of the structure of the first-stage seat assembly of the present invention.

[0040] Figure 7 It is a schematic diagram of the cross-sectional structure of the first-level seat fixture of the present invention;

[0041] Figure 8 yes Figure 7 Cross-sectional view along AA direction;

[0042] Fig. 9 It is a structural schematic diagram of the process of installing the positioning pin of the present invention.

[0043] Among them, 1-electric heating platform, 2-process positioning pin, 3-first-level seat fixture, 4-wooden pressure head, 5-mounting screw, 6-upper pressure block, 7-jet sheet, 8-first-level seat, 9-clamp positioning pin, 10-lower pressure block, 11-positioning pin. DETAILED DESCRIPTION

[0044] In order to more intuitively and clearly describe the structural principles and working methods in the examples of the present invention, the embodiments will be introduced in conjunction with relevant drawings. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] The present invention proposes a device for hot and cold pressing a first-level seat component, comprising a first-level seat, a first-level seat clamp, a wooden pressure head and a heating platform, wherein the first-level seat clamp is arranged on the heating platform, the heating platform heats the first-level seat clamp, and the heating platform is an electric heating platform. An installation groove is arranged inside the first-level seat clamp, a clamp locating pin installation hole is arranged in the installation groove, a clamp locating pin is arranged in the clamp locating pin installation hole, the clamp locating pin and the clamp locating pin installation hole are clearance-matched, a seat hole is arranged on the first-level seat, the clamp locating pin passes through the seat hole on the first-level seat, there are two clamp locating pins, which match the positions and sizes of the two locating holes on the parts assembly; the present invention combines the first-level seat assembly by hot and cold pressing, so that the original interference fit is changed into a clearance fit, and the friction force of the interference bonding surface is increased according to the elastic deformation after cooling, so as to ensure that the deformation stress of the interference bonding surface is reduced, the performance of the servo valve is more stable under high temperature conditions, and the one-time assembly and adjustment qualified rate of the servo valve is steadily improved. Specifically, a heating platform is used to heat the first-level seat to increase the size of its inner hole, but it does not affect the performance of the entire component. The heating platform uses an electric heating platform, and the other part is to place the upper and lower pressing blocks and the jet sheet in a cooling solution with a combination of process positioning pins for cooling, ensuring that the outer circle size of the upper and lower pressing blocks becomes smaller, and using the gap to install the upper and lower pressing blocks and the jet sheet in the first-level seat assembly.

[0046] Among them, the first-level seat is installed in the first-level seat fixture, and then placed in the electric heating platform for heating. The electric heating platform has a certain heat preservation effect. The first-level seat is fixed in the first-level seat fixture with positioning screws.

[0047] Among them, the first-level seat is fixed in the mounting groove of the first-level seat fixture by mounting screws. The flatness of the upper and lower surfaces of the first-level seat is within 0.005, and the parallelism of the upper and lower surfaces of the first-level seat is within 0.005. The seat hole size on the first-level seat matches the outer circle of the part assembly and satisfies a certain interference fit. The sizes are matched one by one and marked to prevent confusion in the installation of parts.

[0048] Among them, the two mounting holes in the first-stage seat fixture for clearance installation of the fixture locating pins are processed by slow walking to ensure the size and position accuracy of the fixture locating pin holes; the function of the two fixture locating pins in the first-stage seat fixture is to prevent the upper and lower pressure blocks and the jet sheet from rotating when installing them, and it also serves as a guide for installing the upper and lower pressure blocks and the jet sheet.

[0049] Among them, the first-level seat, fixture positioning pin, and first-level seat fixture of the present invention are all processed together on an electric heating platform, requiring the first-level seat fixture to be made of a material with a low thermal expansion coefficient and strong heat transfer performance. The low thermal expansion coefficient prevents the first-level seat fixture from expanding and interfering with the position of the first-level seat.

[0050] The present invention proposes a process method for hot and cold pressing a first-stage seat assembly using the device, wherein the method comprises the following steps:

[0051] Step 1: Prepare individual parts of the parts assembly, including an upper pressing block, a lower pressing block, a jet sheet, and two locating pins;

[0052] Step 2: Install the first-stage seat fixture on the heating platform, heat the heating platform to T1 temperature, keep it warm for t hours, combine the upper and lower pressure blocks and the jet sheet with process positioning pins to form a parts assembly, and place the parts assembly in a low-temperature cooling solution; the upper and lower pressure blocks and the jet sheet are combined together with process pins and immersed in the cooling solution to cool down, so that their outer circle size is not affected by the ambient temperature, and the size can be reduced to the micron level, making it easier to install the upper and lower pressure blocks and the jet sheet in the seat hole of the first-stage seat.

[0053] Step 3: Take the parts assembly out of the low-temperature cooling solution, align the two process positioning pins on the parts assembly with the two fixture positioning pins on the first-stage seat fixture. At this time, the lower pressing block is located above the jet sheet, and the upper pressing block is located below the jet sheet. Tap the lower pressing block on the process positioning pin to make the upper pressing block, jet sheet and lower pressing block slide onto the fixture positioning pin. Continue to tap the lower pressing block to knock the parts assembly into the seat hole of the first-stage seat to form a first-stage seat assembly. At this time, the upper and lower pressing blocks and the jet sheet are in contact with the surface of the first-stage seat fixture. At this time, the temperature of the first-stage seat assembly rises to the same temperature as the first-stage seat.

[0054] Step 4: After the first-level seat assembly is cooled to room temperature, align the two locating pins prepared in step 1 with the two fixtures for positioning, install the first-level seat fixture with the first-level seat assembly installed on the vise of the vertical drilling machine, and press the two locating pins into the two locating holes of the first-level seat assembly through the process press head. At the same time, the two fixture locating pins are squeezed out by the locating pins; then, use a wooden press head to knock the lower pressing block so that the surface of the lower pressing block is flush with the upper surface of the first-level seat; install the first-level seat fixture with the first-level seat in the vise, use the medium-deep groove of the vise to avoid the spatial interference caused by the extrusion of the fixture locating pin, then align the locating pin with the fixture locating pin, use the elastic chuck of the vertical drilling machine to clamp the process press head, and press the locating pin, press the locating pin until it is flush with the first-level seat, press the two locating pins in turn, and take out the first-level seat assembly after all the two locating pins are pressed in.

[0055] Among them, in this step, after the first-stage seat assembly cools to room temperature, check that the upper and lower pressing blocks are not allowed to fall off, and measure whether the parallelism between the surface of the upper pressing block and the surface of the first-stage seat meets the requirements.

[0056] Step 5: Place the first-stage seat assembly under a 30x tool microscope to check whether the symmetry and verticality meet the requirements;

[0057] Step 6: Perform a pressure test on the first-stage seat assembly that meets the requirements in step 5 on a pressure test bench to ensure that the pressure in the two chambers of the first-stage seat assembly meets the design specifications.

[0058] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A device for hot and cold pressing of a first-stage seat assembly, characterized in that: It includes a first-level seat, a first-level seat fixture and a heating platform. The first-level seat fixture is arranged on the heating platform, and the heating platform heats the first-level seat fixture. A mounting groove is arranged inside the first-level seat fixture, a fixture locating pin mounting hole is arranged in the mounting groove, a fixture locating pin is arranged in the fixture locating pin mounting hole, and the fixture locating pin and the fixture locating pin mounting hole have a clearance fit. A seat hole is arranged on the first-level seat, and the fixture locating pin passes through the seat hole on the first-level seat.

2. The device for hot and cold pressing of a first-stage seat assembly according to claim 1, characterized in that: There are two fixture locating pins, which match the positions and sizes of the two locating holes on the part assembly.

3. The device for hot and cold pressing of a first-stage seat assembly according to claim 2, characterized in that: The device also includes a wooden pressing head.

4. The device for hot and cold pressing of a first-stage seat assembly according to claim 3, characterized in that: The first-stage seat is fixed in the mounting groove of the first-stage seat fixture by mounting screws. The flatness of the upper and lower surfaces of the first-stage seat is within 0.005, the parallelism of the upper and lower surfaces of the first-stage seat is within 0.005, and the seat hole size on the first-stage seat matches the outer circle of the part assembly and satisfies a certain interference.

5. The device for hot and cold pressing of a first-stage seat assembly according to claim 4, characterized in that: The first-stage seat fixture is made of a material with a low thermal expansion coefficient and strong heat transfer performance.

6. A process for hot and cold pressing a first-stage seat assembly using the device as claimed in claim 5, characterized in that: The method comprises the following steps: Step 1: Prepare individual parts of the parts assembly, including an upper pressing block, a lower pressing block, a jet sheet, and two locating pins; Step 2: Install the first-level seat fixture on the heating platform, heat the heating platform to T1 temperature, keep it warm for t hours, combine the upper and lower pressing blocks and the jet sheet with process positioning pins to form a parts assembly, and place the parts assembly in a low-temperature cooling solution; Step 3: Take the parts assembly out of the low-temperature cooling solution, align the two process positioning pins on the parts assembly with the two fixture positioning pins on the first-stage seat fixture. At this time, the lower pressing block is located above the jet sheet, and the upper pressing block is located below the jet sheet. Tap the lower pressing block on the process positioning pin to make the upper pressing block, jet sheet and lower pressing block slide onto the fixture positioning pin. Continue to tap the lower pressing block to knock the parts assembly into the seat hole of the first-stage seat to form a first-stage seat assembly. At this time, the temperature of the first-stage seat assembly rises to the same temperature as the first-stage seat. Step 4: After the first-stage seat assembly cools to room temperature, align the two locating pins prepared in step 1 with the two fixtures for positioning. Use the process press of the vertical drilling machine to press the two locating pins into the two positioning holes of the first-stage seat assembly. At the same time, the two fixture locating pins are squeezed out by the locating pins. Then, use a wooden press to knock the lower pressing block so that the surface of the lower pressing block is flush with the upper surface of the first-stage seat.

7. The process according to claim 6, characterized in that: The method also includes step 5: placing the first-stage seat assembly under a 30x tool microscope to check whether the symmetry and verticality meet the requirements.

8. The process according to claim 7, characterized in that: The method further includes step 6: performing a pressure test on the first-stage seat assembly that meets the requirements in step 5 on a pressure test bench to ensure that the pressures in the two chambers of the first-stage seat assembly meet the design specifications.

9. The process according to claim 8, characterized in that: In step 4, after the first-stage seat assembly cools to room temperature, check that the upper and lower pressing blocks are not allowed to fall off, and measure whether the parallelism between the surface of the upper pressing block and the surface of the first-stage seat meets the requirements.

10. The process according to claim 9, characterized in that: In step 4, the first-stage seat fixture with the first-stage seat assembly installed is installed on the vise of the vertical drilling machine, and two locating pins are pressed into the two locating holes of the first-stage seat assembly by the process press head. At the same time, the two fixture locating pins are squeezed out by the locating pins.

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