Part end face pin assembling device and method based on thermal expansion and cold contraction principle

Abstract

The application is a kind of part end face pin assembly device and assembly method based on the principle of thermal expansion and cold contraction, characterized in that it comprises a pin pressing mechanism (1), a positioning pin guide sleeve (3) and an electric heating sheet (4); the lower end side of the pin pressing mechanism (1) is fixed to the side of the workpiece (5) to be assembled with the positioning pin; the positioning pin guide sleeve (3) is used for guiding and limiting the positioning pin (2) and can also be made into an integral part connected with the lower end surface of the pressing rod (16) of the pin pressing mechanism (1); the electric heating sheet (4) is used for being attached to the vicinity of the positioning pin hole (51) of the workpiece (5) to be assembled with the positioning pin, for heating the surrounding area of the positioning pin hole (51), and the electric heating sheet (4) is provided with a hole in the middle; the application realizes the rapid and accurate assembly of the pin by controlling the temperature change of the material around the assembly hole, reduces the damage to the pin, the assembly hole and the parts such as the material around the assembly hole, and improves the assembly precision and efficiency.

Description

Technical Field

[0001] This invention relates to the field of mechanical assembly technology, specifically to a device and assembly method for assembling pins using the principle of thermal expansion and contraction. Background Technology

[0002] In mechanical assembly, pins are commonly used to position components. Traditional pin-hole fits are usually transition fits or interference fits, and assembly methods include hammering and pressure assembly. These methods can easily lead to deformation or damage of components, especially in high-precision assembly. Summary of the Invention

[0003] The purpose of this invention is to provide a part end face pin assembly device and assembly method based on the principle of thermal expansion and contraction. By controlling the temperature change of the material around the assembly hole, the pin can be assembled quickly and accurately, reducing damage to the pin, assembly hole and surrounding materials, and improving assembly accuracy and efficiency.

[0004] A part end face pin assembly device based on the principle of thermal expansion and contraction is characterized by comprising a pin pressing mechanism 1, a positioning pin guide sleeve 3, and an electric heating element 4; the lower side of the pin pressing mechanism 1 is fixed to the side of the workpiece 5 to be assembled with the positioning pin; the positioning pin guide sleeve 3 is used for guiding and limiting the positioning pin 2, and it is a handheld part, or it can be made into a part that is integrated with the lower end face of the pressing rod 16 of the pin pressing mechanism 1; the electric heating element 4 is used to attach to the vicinity of the positioning pin hole 51 of the workpiece 5 to be assembled with the positioning pin, and is used for heating the area around the positioning pin hole 51. The electric heating element 4 has a hole in the middle, and the diameter of the hole is larger than that of the positioning pin 2, so that the positioning pin 2 can pass through the hole when it is pushed by the pin pressing mechanism 1.

[0005] The pressing pin mechanism 1 includes a push rod 11, a base 12, a support 13, multiple connecting pins 14, two connecting rods 15, a pressing rod 16, and a workpiece fixing pin 17;

[0006] The push rod 11 includes a handle 113 and a rod arm 114. The rod arm 114 is connected to the lower end of the handle 113. The rod arm 114 is L-shaped and has two connecting holes, namely a first connecting hole 111 and a second connecting hole 112.

[0007] The base 12 includes a double lug connector 121, a back plate 122, a connecting post 123, and a sleeve 124; the double lug connector 121 is disposed on the upper part of the connecting post 123, the sleeve 124 is disposed on the lower part of the connecting post 123, the back plate 122 is disposed on the other side of the connecting post 123, and the back plate 122 is provided with a plurality of screw holes.

[0008] The support 13 includes a square plate 131, a vertical plate 132, and an arc-shaped plate 133. The square plate 131 is located at the upper end of the vertical plate 132, and the arc-shaped plate 133 is located at the lower end of the vertical plate 132. The square plate 131 has multiple screw holes 134, and the hole positions of the screw holes 134 correspond to the screw holes on the back plate 122 of the base 12. Each end of the arc-shaped plate 133 has a positioning hole 135. The screw holes allow the arc-shaped plate 133 to be connected to the workpiece 5 to be assembled with the positioning pin through the workpiece fixing pin 17.

[0009] Connecting rod 15 is a Z-shaped part with a through hole at each end;

[0010] The pressure rod 16 is a cylindrical part with a flat end at the top and a transverse through hole.

[0011] The back plate 122 on the base 12 is fixedly connected to the square plate 131 of the support 13 by screws; the first connecting hole 111 of the rod arm 114 of the push rod 11 is hinged to the double lug connecting seat 121 of the base 12 by connecting nail 14; the second connecting hole 112 of the rod arm 114 of the push rod 11 is hinged to the holes at the upper ends of the two connecting rods 15 by connecting nail 14; the pressure rod 16 is installed in the sleeve 124 of the base 12, and the pressure rod 16 can slide up and down in the sleeve 124; the lower ends of the two connecting rods 15 are hinged to the holes at the upper ends of the pressure rod 16.

[0012] During operation, the arc-shaped plate 133 of the support 13 is fixed to the side wall of the workpiece 5 to be assembled with the positioning pin using the workpiece fixing nail 17. Then, the electric heating plate 4 is attached to the positioning pin hole and surrounding area of ​​the workpiece 5 to be assembled with the positioning pin, and the hole on the electric heating plate 4 is made concentric with the positioning pin hole. Then, the electric heating plate 4 is heated. After the positioning pin hole and surrounding area of ​​the workpiece 5 to be assembled with the positioning pin reach the set temperature, the positioning pin 2 is inserted into the positioning pin hole of the workpiece 5 to be assembled with the positioning pin through the guide sleeve 3. Then, the push rod 11 is rotated so that the pressure rod 16 presses on the positioning pin 2. When the positioning pin 2 is pressed into the positioning pin hole and the positioning pin 2 reaches the set position, the positioning pin guide sleeve 3 and the electric heating plate 4 are removed, the pressing mechanism 1 is disassembled, and the assembly of the positioning pin 2 is completed.

[0013] The method for assembling pins using a part end-face pin assembly device based on the principle of thermal expansion and contraction is characterized by comprising the following steps:

[0014] Step 1: Determine the heating temperature range based on the temperature resistance range of the pin hole material, calculate the expansion amount of the pin hole diameter after heating, and compare it with the interference of the pin hole fit; there are two cases: Case 1: The expansion amount of the pin hole is greater than the maximum interference of the fit, the positioning pin 2 is directly installed into the pin hole without pressing the pin mechanism 1; Case 2: The expansion amount of the pin hole is less than or equal to the maximum interference, the positioning pin 2 must be assembled using the pin mechanism 1; the following are the steps for using the pin mechanism 1.

[0015] Step 2: Fix the pressing pin mechanism 1 to the side wall of the workpiece 5 to be assembled with the positioning pin using the workpiece fixing pin 17;

[0016] Step 3: Fix the electric heating element 4 on the surface of the workpiece 5 where the positioning pin is to be assembled. Set the heating temperature of the electric heating element 4 to heat the area around the pin hole of the workpiece 5 to be assembled, so that the pin hole expands.

[0017] Step 4: When the electric heating element 4 heats up to the set temperature, insert the locating pin 2 at room temperature into the guide hole of the locating pin guide sleeve 3, so that it is aligned with the locating pin hole of the workpiece 5 to be assembled with the locating pin.

[0018] Step 5: Use the pressing mechanism 1 to press the positioning pin 2 into the positioning pin hole of the workpiece 5 to be assembled with the positioning pin, and then remove the positioning pin guide sleeve 3 and the electric heating element 4.

[0019] Step 6: After assembly, cool the workpiece 5 with the locating pin to room temperature by air cooling or natural cooling.

[0020] Step 7: Disassemble the pressing pin mechanism 1 and assemble the positioning pin 2.

[0021] Beneficial effects of this invention:

[0022] 1. This invention pioneers a new method for installing interference fit locating pins. By utilizing the principle of thermal expansion and contraction, the locating pins are installed, which greatly improves the quality of products equipped with locating pins and achieves extremely high product precision. This provides a method for products that must use interference fits with locating pins to achieve a very precise interference fit.

[0023] 2. This invention achieves rapid and precise assembly of pins by controlling the temperature change of the material around the assembly hole, reducing damage to the pins, assembly holes, and surrounding materials, and improving assembly accuracy and efficiency.

[0024] 3. For assemblies requiring interference fit, this invention greatly improves the assembly precision, and is particularly suitable for products in the fields of aerospace, precision instruments and other fields. Attached Figure Description

[0025] Figure 1 A schematic diagram of the working state of the device of the present invention (including positioning pins and workpieces);

[0026] Figure 2 A schematic diagram of the pressing pin mechanism of the present invention;

[0027] Figure 3 A schematic diagram of the push rod structure of the present invention;

[0028] Figure 4 A schematic diagram of the base structure of this invention;

[0029] Figure 5 A schematic diagram of the connecting rod structure of the present invention;

[0030] Figure 6 A schematic diagram of the pressure bar structure of the present invention;

[0031] (a) A perspective view of the pressure bar structure of the present invention;

[0032] (b) Front view of the pressure bar structure of the present invention;

[0033] (c) Left view of Figure (b);

[0034] Figure 7 A schematic diagram of the support structure of the present invention. Detailed Implementation

[0035] 1. Application of the principle of thermal expansion and contraction

[0036] Before assembly, the material near the pin hole is heated to a certain temperature (usually 100℃ to 150℃ for aluminum alloys and magnesium alloys, and 200℃ to 400℃ for titanium alloys and stainless steel, the specific temperature is determined according to the interference fit of the pin and the temperature range of the material), so that the diameter of the pin hole expands due to heat. Then, the pin at room temperature is inserted into the pin hole. After the pin hole cools down, its diameter shrinks, forming a tight fit with the pin.

[0037] 2. Pressure assembly method

[0038] Pressure assembly is a supplementary assembly method for pin assembly, primarily considered when the diameter expansion of the pin hole after heating to a specific temperature is still less than the interference fit between the pin and the hole. That is, after the pin hole diameter increases due to heating to a specific temperature, a special fixture or pressure equipment is used to press the pin into the hole.

[0039] 3. Cooling process control

[0040] After assembly, the pin hole is cooled by natural cooling or air cooling to ensure its fit with the pin.

[0041] 4. Positioning pin heating and pressing device

[0042] This invention provides a heating and pressing device for assembling positioning pins on the surface of a workpiece, which is used to achieve non-destructive assembly of positioning pins on the surface of a workpiece.

[0043] The schematic diagram of this device is shown in the attached drawing, which includes a pressing mechanism 1, a positioning pin guide sleeve 3, and an electric heating element 4. The pressing mechanism 1 is fixed to the side of the workpiece using a workpiece fixing pin 17; the positioning pin guide sleeve 3 is used for guiding and limiting the positioning pin, and is a handheld part, or it can be made into a part integrated with the pressing mechanism; the electric heating element 4 is attached to the vicinity of the positioning pin hole of the workpiece for heating the area around the positioning pin hole. The electric heating element has a hole in the middle, which is slightly larger than the pin, so that the pin can pass through the hole when it is pushed by the pressing mechanism.

[0044] The aforementioned pressing mechanism mainly consists of a push rod 11, a base 12, a support 13, a connecting pin 14, a connecting rod 15, a pressing rod 16, and a workpiece fixing pin 17. The push rod 11 can rotate around the base 12 when pushed by hand, and drives the pressing rod 16 to move up and down along the sleeve axis of the base 12 through the connecting rod 15.

[0045] The push rod 11 has a handle and a rod arm. The handle and the rod arm are at a certain angle (90° in the schematic diagram), and the handle can be round or other shapes. The rod arm has two connecting holes. The connecting hole 112 is hinged to one end of the connecting rod 15 through the connecting pin 14, and the other hole 111 is hinged to the hole at the upper end of the base 12 through the connecting pin 14.

[0046] The upper end of the base 12 has a connecting hole for the connecting nail 14 to pass through and fix the push rod; the lower end has a pressure tube sleeve through which the pressure rod can pass and reciprocate along the axis of the sleeve; the base has a back plate with four holes.

[0047] The upper end of the support 13 has a square plate with four holes. The hole positions are consistent with the four holes on the back plate of the base 12. The support 13 is fixed to the back plate of the base 12 by screws and nuts. The lower end of the support 13 is the workpiece fixing part. The shape conforms to the surface of the workpiece and is either curved or flat (the schematic diagram shows a curved surface). There are also no less than two through holes, which are consistent with the holes on the workpiece, and are used to fix the support 13 to the workpiece.

[0048] The connecting rod 15 is a Z-shaped part with a through hole at each end. One end is connected to the through hole 112 of the push rod 11 through the connecting pin 14, and the other end is connected to the upper connecting hole of the pressure rod 16 through the connecting pin 14.

[0049] The pressure rod 16 is a cylindrical part with a flat upper end and a transverse through hole. The through hole is used to achieve hinge connection with the lower through hole of the connecting rod 15 through the connecting nail 14.

[0050] The workpiece fixing pin 17 is a fixing screw, and its diameter matches the hole on the workpiece 5 to be assembled with the positioning pin.

[0051] The method of the present invention

[0052] Step 1: Determine the heating temperature range based on the temperature resistance range of the pin hole material, calculate the expansion amount of the pin hole diameter after heating, and compare it with the interference fit of the pin hole. If the expansion amount of the pin hole is less than the maximum interference fit, then fix the pin pressing mechanism 1 of this device to the part where the pin hole is located.

[0053] Step 2: Fix the heating module (built-in electric heating element) of this device onto the surface where the pin hole is located, set the heating temperature, and heat the pin hole to expand its diameter.

[0054] Step 3: Insert the pin at room temperature into the pin hole (if the expansion of the pin hole is less than the maximum interference fit, use the pin pressing mechanism 1 of this device to press the pin into the heated pin hole).

[0055] Step 4: After assembly, allow the pin holes to cool to room temperature using air cooling or natural cooling.

[0056] Step 5: Disassemble the pin assembly.

[0057] Example 1:

[0058] The pin and pin hole fit is φ5H6 / n5.

[0059] For the pin hole, its upper limit dimension is 5.008 mm, and its lower limit dimension is 5.000 mm.

[0060] For the pin, its upper limit dimension is 5.013mm and its lower limit dimension is 5.008mm.

[0061] Lower limit dimension of pin hole - Upper limit dimension of pin = 5.000 - 5.013 = -0.013 (mm) = -13 (μm)

[0062] Upper limit dimension of the pin hole - Lower limit dimension of the pin = 5.008 - 5.008 = 0

[0063] Therefore, the pin-hole fit is an interference fit with a maximum interference of 13 μm and a minimum interference of 0.

[0064] The part containing the pin hole is made of aluminum alloy, and the coefficient of linear expansion of aluminum alloy is taken as 23.6 × 10⁻⁶. -6 / ℃, calculated based on heating to 150℃ (room temperature 20℃, temperature rise 130℃), its expansion amount = 23.6 × 10 -6 ×130×5×10 3 =15.34 (μm).

[0065] The expansion of the pin hole after heating (15.34μm) is greater than the maximum interference (13μm). That is, after the pin hole is heated to the preset temperature, the interference fit is changed to a clearance fit, and the pin can be directly inserted into the pin hole.

[0066] Example 2:

[0067] The pin and pin hole fit is φ5H6 / p5.

[0068] For the pin hole, its upper limit dimension is 5.008 mm, and its lower limit dimension is 5.000 mm.

[0069] For the pin, its upper limit dimension is 5.017 mm and its lower limit dimension is 5.012 mm.

[0070] Lower limit dimension of pin hole - Upper limit dimension of pin = 5.000 - 5.017 = -0.017 (mm) = -17 (μm)

[0071] Upper limit dimension of the pin hole - lower limit dimension of the pin = 5.008 - 5.012 = -0.004 (mm) = -4 (μm)

[0072] Therefore, the pin-hole fit is an interference fit with a maximum interference of 17 μm and a minimum interference of 4 μm.

[0073] The part containing the pin hole is made of titanium alloy, and the coefficient of linear expansion of titanium alloy is taken as 8.6 × 10⁻⁶. -6 / ℃, calculated based on heating to 220℃ (room temperature 20℃, temperature rise 200℃), its expansion amount = 8.6 × 10 -6 ×200×5×10 3 =8.6 (μm).

[0074] The minimum interference fit (4μm) < the expansion of the pin hole after heating (8.6μm) < the maximum interference fit (17μm). That is, after the pin hole is heated to the preset temperature, the interference fit changes to the transition fit. The pin cannot be directly inserted into the pin hole. It is necessary to adjust the preset temperature or use the pin pressing mechanism 1 to press the pin into the heated pin hole.

Claims

1. A part end face pin assembly device based on the principle of thermal expansion and contraction, characterized in that, It includes a pressing pin mechanism (1), a positioning pin guide sleeve (3), and an electric heating element (4); the lower side of the pressing pin mechanism (1) is fixed to the side of the workpiece (5) to be assembled with the positioning pin; the positioning pin guide sleeve (3) is used for guiding and limiting the positioning pin (2), and it is a handheld part, or it can be made into a part connected to the lower end face of the pressing rod (16) of the pressing pin mechanism (1); the electric heating element (4) is used to be attached to the vicinity of the positioning pin hole (51) of the workpiece (5) to be assembled with the positioning pin, and is used for heating the area around the positioning pin hole (51). The electric heating element (4) has a hole in the middle, and the diameter of the hole is larger than that of the positioning pin (2) so that the positioning pin (2) can pass through the hole when it is pushed by the pressing pin mechanism (1); The pressing pin mechanism (1) includes a push rod (11), a base (12), a support (13), multiple connecting pins (14), two connecting rods (15), a pressing rod (16), and a workpiece fixing pin (17). The push rod (11) includes a handle (113) and a rod arm (114), with the rod arm (114) connected to the lower end of the handle (113). The rod arm (114) is L-shaped and has two connecting holes, namely a first connecting hole (111) and a second connecting hole (112). The base (12) includes a double lug connector (121), a back plate (122), a connecting post (123), and a sleeve (124); the double lug connector (121) is located on the upper part of the connecting post (123), the sleeve (124) is located on the lower part of the connecting post (123), the back plate (122) is located on the other side of the connecting post (123), and the back plate (122) is provided with multiple screw holes; The support (13) includes a square plate (131), a vertical plate (132), and an arc-shaped plate (133). The square plate (131) is located at the upper end of the vertical plate (132), and the arc-shaped plate (133) is located at the lower end of the vertical plate (132). The square plate (131) has multiple screw holes (134), and the hole positions of the screw holes (134) correspond to the screw holes on the back plate (122) of the base (12). The arc-shaped plate (133) has a positioning hole (135) at each end. The screw holes can connect the arc-shaped plate (133) to the workpiece (5) to be assembled with the positioning pin through the workpiece fixing pin (17). The connecting rod (15) is a Z-shaped part with (1) through hole at each end; The pressure rod (16) is a cylindrical part with a flat end at the top and a transverse through hole. The back plate (122) on the base (12) is fixedly connected to the square plate (131) of the support (13) by screws; the first connecting hole (111) of the rod arm (114) of the push rod (11) is hinged to the double lug connecting seat (121) of the base (12) by connecting nail (14); the second connecting hole (112) of the rod arm (114) of the push rod (11) is hinged to the hole at the upper end of the two connecting rods (15) by connecting nail (14); the pressure rod (16) is installed in the sleeve (124) of the base (12), and the pressure rod (16) can slide up and down in the sleeve (124); the lower end of the two connecting rods (15) is hinged to the hole at the upper end of the pressure rod (16); During operation, the arc plate (133) of the support (13) is fixed to the side wall of the workpiece (5) to be assembled with the positioning pin using the workpiece fixing nail (17). Then, the electric heating plate (4) is attached to the positioning pin hole and surrounding area of ​​the workpiece (5) to be assembled with the positioning pin, and the hole on the electric heating plate (4) is concentric with the positioning pin hole. Then, the electric heating plate (4) is heated. After the positioning pin hole and surrounding area of ​​the workpiece (5) to be assembled with the positioning pin reach the set temperature, the positioning pin (2) is inserted into the positioning pin hole of the workpiece (5) to be assembled with the positioning pin through the guide sleeve (3). Then, the push rod (11) is rotated so that the pressure rod (16) presses on the positioning pin (2). When the positioning pin (2) is pressed into the positioning pin hole and the positioning pin (2) reaches the set position, the positioning pin guide sleeve (3) and the electric heating plate (4) are removed, the pressing mechanism (1) is disassembled, and the assembly of the positioning pin (2) is completed.

2. The method for assembling pins using the part end-face pin assembly device based on the principle of thermal expansion and contraction as described in claim 1, characterized in that... Includes the following steps: Step 1: Determine the heating temperature range based on the temperature resistance range of the pin hole material, calculate the hole diameter expansion after heating, and compare it with the interference fit of the pin hole; there are two cases: Case 1: the expansion of the pin hole is greater than the maximum interference fit, the positioning pin (2) is not pressed in without the pin pressing mechanism (1), and the positioning pin (2) is directly installed into the pin hole; Case 2: the expansion of the pin hole is less than or equal to the maximum interference fit, the pin pressing mechanism (1) must be used to assemble the positioning pin (2); the following are the steps for using the pin pressing mechanism (1); Step 2: Use workpiece fixing pins (17) to fix the pressing pin mechanism (1) to the side wall of the workpiece (5) to be assembled with the positioning pin; Step 3: Fix the electric heating element (4) on the surface of the pin hole of the workpiece (5) to be assembled with the positioning pin, set the heating temperature of the electric heating element (4) to heat the area around the pin hole of the workpiece (5) to be assembled with the positioning pin, so that the pin hole expands. Step 4: When the electric heating element (4) is heated to the set temperature, insert the locating pin (2) at room temperature into the guide hole of the locating pin guide sleeve (3) so that it is aligned with the locating pin hole of the workpiece (5) to be assembled with the locating pin. Step 5: Use the pressing mechanism (1) to press the positioning pin (2) into the positioning pin hole of the workpiece (5) to be assembled with the positioning pin, and then remove the positioning pin guide sleeve (3) and the electric heating element (4). Step 6: After assembly, cool the workpiece (5) to be assembled with the positioning pin to room temperature by air cooling or natural cooling. Step 7: Disassemble the pressing pin mechanism (1) and assemble the positioning pin (2).

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