A thermal expansion mold and a rapid processing method of a thermal expansion type part

Abstract

The application discloses a thermal expansion type mold and a rapid processing method of thermal expansion type parts, and the thermal expansion type mold comprises a lower mold plate, a top plate, a cone, an expansion petal, an upper mold plate, an embedded block, an adjusting piece, a guide key, a first screw, a bolt, a cylindrical pin, a second screw, a lifting bolt and a third screw. The cone and the top plate are in sliding fit, the top plate and the expansion petal are in inclined plane sliding fit, and the cone and the expansion petal are in inclined plane sliding fit. The cone, the top plate and the expansion petal are all designed on the side close to the lower mold plate. The thermal expansion type mold is used, and thermal expansion type parts can be processed in batches after the mold is heated once. When pressing, the top plate is separated from the expansion petal, the pressing force is small, rapid pressing can be realized, the processing cost is low, the processing flexibility is high, semi-automatic part loading and taking are realized, and the thermal expansion type mold only needs to be installed once.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a rapid machining method for thermal expansion molds and thermal expansion type parts. Background Technology

[0002] The machining of many large rotating parts relies on thermal expansion under high-temperature conditions, such as the machining of aluminum, copper, and titanium alloy parts. Aluminum and copper alloy rotating parts are widely used in everyday life and the automotive industry, while titanium alloy rotating parts are extensively used in key components of aero-engines. Currently, the mainstream thermal expansion type parts (such as...) Figure 1 The single-piece processing of this method involves a process of mold installation, heating, pressing, cooling, and mold removal, which is time-consuming, labor-intensive, and costly. Currently, no publicly available literature on this type of rapid processing method has been found, either domestically or internationally. Summary of the Invention

[0003] This invention aims to provide a rapid processing method for thermal expansion molds and thermal expansion-type parts, enabling rapid processing of thermal expansion-type parts, meeting the requirements of efficient, fast, and reliable processing. The pressing force during expansion is small, and rapid pressing can be achieved. The optimal processing time can be selected according to the actual material to achieve the best performance of the parts. Semi-automatic loading and unloading of parts is achieved, and the mold only needs to be installed once.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A thermal expansion mold, comprising: The lower template has through holes for lifting and lowering the top rod; A cone is installed on the upper end face of the lower template. The outer surface of the cone includes a cylindrical surface and a plurality of first inclined planes located above the cylindrical surface. The plurality of first inclined planes are centrally symmetrically distributed with the axis of the cylindrical surface as the center. The outer diameter formed by the upper end of the plurality of first inclined planes is smaller than the outer diameter formed by the lower end of the plurality of first inclined planes. A guide key is installed on the first inclined plane. The guide key is in the shape of a cuboid. The top plate is an annular component that is fitted onto the cylindrical surface of the cone through the inner annular hole of the annular component to form a sliding fit with the cylindrical surface. The upper end surface of the top plate includes multiple second inclined planes, which are centrally symmetrically distributed with the axis of the inner annular hole of the annular component as the center. The outer diameter formed by the lower end of the multiple second inclined planes is smaller than the outer diameter formed by the upper end of the multiple second inclined planes. The expansion flap has a surface including an outer expansion surface, an inner third inclined plane, a guide groove, and a lower fourth inclined plane. The third inclined plane and the first inclined plane form a planar sliding fit, the guide groove and the guide key form a sliding fit, the cross-section of the guide groove is U-shaped, and the fourth inclined plane and the second inclined plane form a planar sliding fit. The upper template is located above the expansion valve.

[0005] As one option, the thermal expansion mold also includes an insert mounted on the expansion flap, the insert having a raised ridge on its outer surface for pressing out a angular marker on the surface of the part.

[0006] As one option, the thermal expansion mold also includes an adjusting plate installed between the top plate and the lower template. The outer diameter of the expansion flap is adjusted by changing the thickness of the adjusting plate.

[0007] As one option, the top plate, cone, and expansion flap are made of medium silicon molybdenum ductile iron.

[0008] As one solution: The number of the expansion valves is 4 to 16; The planar sliding fit angle between the third inclined plane and the first inclined plane is 30° to 80°; The cone angle of the first inclined plane is 5° to 30°.

[0009] As one solution: A guide key mounting groove is provided on the first inclined plane, and the guide key is mounted in the guide key mounting groove by a first screw; Bolts are installed on the circumferential surface of the upper template; The cone is mounted on the lower template by a cylindrical pin and a second screw; Lifting bolts are installed on the lower template.

[0010] A rapid machining method for thermally expandable parts, comprising: Step 1, preparing raw material: After retaining a certain allowance and expansion amount based on the final size of the part, unfold it to obtain the unfolded material for thermal expansion of the part. Then, the unfolded material is rolled and welded to form an initial rotating body. The end face of the initial rotating body is provided with lifting lugs for picking up the part. Step 2: Heat the thermal expansion mold as described in the claim to a predetermined temperature. Use the ejector rod to lift the top plate upwards. The top plate drives the expansion petals to move closer to the cone, reducing the diameter of the expansion mold composed of multiple expansion petals. Fit the initial rotating body into the multiple expansion petals. The ejector rod descends, and the top plate moves down accordingly. The multiple expansion petals fall under their own weight, thereby expanding the diameter of the expansion mold until the initial rotating body is fully expanded. The top plate moves down to the bottom and is kept at the temperature for a period of time. Then, drive the upper template to press down to the bottom (the upper template drives the expansion petals to press down until the expansion petals are pressed tightly against the top plate). Use the ejector rod to lift the top plate upwards, reducing the diameter of the expansion mold composed of multiple expansion petals. Remove the completed thermal expansion molded part.

[0011] As one possible approach, in step one, the lifting lugs are either pre-reserved on the unfolded material or welded after the initial rotating body is formed.

[0012] As one possible solution, in step two, a retrieval cart is used to retrieve the parts. The retrieval cart includes: A vehicle frame, with rollers mounted on its lower end; An electric lifter, wherein the electric lifter is mounted on the upper end of the vehicle frame; A push rod, which is slidably mounted on an electric lifter, has a crossbeam at its end; The hooks, at least two of which are mounted on the crossbeam of the push rod, are adjustable in spacing.

[0013] As one approach, in step two, when the final rotating cross-sectional shape of the bulging part is complex, before heating the thermal expansion mold to a predetermined temperature, the concave mold corresponding to the rotating cross-sectional shape is first installed on the outside of the bulging petals.

[0014] The thermal expansion mold of the present invention has the following characteristics: (1) The cone and the expansion flap are both designed at the bottom (near the lower template side), which effectively reduces the opening and closing height; (2) Make the upper surface of the top plate into an inclined plane. When pressing, the expansion petals slide down the cone by their own weight and expand. After the part cylinder wall is tightened, the top plate is moved to the bottom. The top plate does not participate in the pressing process and is only used when the material is unloaded. This reduces the pressing force and the friction of the expansion petals, reduces the pressing time and pressing force, and reduces mold wear. (3) The expansion flap adopts a slanted plane design. During the entire pressing process, the expansion flap is fully slanted plane in contact with the cone, the expansion flap is evenly stressed, and there is no risk of tipping over. (4) The expansion flap adopts a rectangular cross-section guide key (cubic prism) design, which not only avoids the traditional "T" shaped key jamming at high temperature, but also plays a guiding role, making the expansion flap expansion more stable and preventing uneven force from causing the expansion flap to tilt.

[0015] In traditional thermal expansion molding methods, each mold produces one piece per furnace, resulting in a long processing time per piece. The process typically involves heating (5-10 hours), pressing (0.5-2 hours), cooling (10-15 hours), and unloading (1 hour). During pressing, the expansion blocks move on a horizontal top plate, requiring significant force and minimal displacement under hot conditions, leading to long pressing times and high costs for labor, electricity, and equipment. Since the parts are processed in the furnace, the time cannot be freely controlled, potentially affecting the physical, chemical, and mechanical properties of the parts. Each piece requires loading and unloading the mold, necessitating repeated mold hoisting. The expansion flaps require manual contraction and retraction, which can easily damage the connecting guide keys.

[0016] Compared to traditional thermal expansion methods, the thermal expansion mold of this invention offers several advantages in processing time. After a single heating of the mold, batch production is possible, and the processing time for each part is controllable, depending on the actual process requirements, with a minimum completion time of 5 minutes. During pressing, the top plate detaches from the expansion flaps, resulting in lower pressing force and enabling rapid pressing. Regarding processing costs, this invention offers relatively low costs. In terms of part quality, the processing method allows for optimal processing time selection based on the actual material, achieving the best part performance. Finally, this invention enables semi-automatic part loading and unloading, requiring only one mold installation. Attached Figure Description

[0017] Figure 1 It is a planar sketch of a part that requires thermal expansion. Figure 2 This is a schematic diagram of the thermal expansion mold structure in this invention; Figure 3 This is a schematic diagram of the pickup vehicle in this invention; Figure 4 This is a part cutting diagram. The two unfolded pieces in the diagram are welded together to form a conical cylinder. Figure 5 yes Figure 4 The initial rotating body formed by welding two pieces of unfolded material together; Figure 6 This is a diagram of the expanded flap structure in this invention; Figure 7 This is a diagram of the cone structure in this invention; Figure 8 This is a diagram of the top plate structure in this invention; Figure 9 This is a structural diagram of the guide key in this invention; Figure 10 This is a diagram of the block structure in this invention; In the diagram, 1. Lower template; 2. Top plate; 3. Cone; 4. Expansion flap; 5. Upper template; 6. Insert; 7. Adjusting plate; 8. Guide key; 9. First screw; 10. Bolt; 11. Cylindrical pin; 12. Second screw; 13. Lifting bolt; 14. Third screw; 15. Frame; 16. Push rod; 17. Electric lifter; 18. Hook; 31. Cylindrical surface; 32. First inclined plane; 21. Second inclined plane; 41. Third inclined plane; 42. Fourth inclined plane. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0019] To improve the processing efficiency of thermally expandable parts, the thermally expandable mold is designed as follows: Figure 2 This structure allows for automatic demolding of parts. After demolding, a parts retrieval trolley is used... Figure 3 Loading and unloading parts enables rapid processing.

[0020] The objective of this invention is achieved through the following technical solution: (1) Making thermal expansion molds: Figure 2 The structure makes the top plate 2 into an inclined plane, and uses the self-weight of the expansion flap 4 to automatically shrink under heat, thereby realizing automatic demolding and expansion of the parts.

[0021] (2) Fabrication of a parts retrieval cart: After the parts are demolded, a parts retrieval cart is used to achieve rapid loading and unloading at high temperatures. The structure of the parts retrieval cart is as follows: Figure 3 .

[0022] (3) Raw material preparation: Based on the part dimensions, prepare the initial rotating body raw material after reserving a certain allowance and bulging amount. Taking two weld seams as an example... Figure 4 .

[0023] (4) Parts processing: After the mold is heated to the predetermined temperature, the parts are sent in by the part removal cart. The pressing time is selected according to the actual part process. The parts are taken out and placed in the designated position. Then the processing of the next part is repeated.

[0024] Making thermal expansion molds: a. Selection of main materials: The selection is based on the actual processing temperature, batch size, and cost. This invention uses medium-silicon molybdenum ductile iron as an example, which can operate stably in environments ranging from 650℃ to 820℃. It offers high cost-effectiveness. Other materials, such as screws and pins, are made of 1Cr18Ni9Ti.

[0025] b. Mold structure: For details of the thermal expansion mold structure and its main components, please see [link to details]. Figures 2 to 10 .

[0026] 1. Inflatable valve 4 (e.g.) Figure 6The number of expansion petals 4 depends on the diameter and height of the part and the diameter of the given blank. Generally, they are divided into 4 to 16 pieces. After the part and blank are de-ejected, the more pieces of expansion petals 4 there are, the smaller the volume, the lower the strength, and the smaller the gap between the expansion petals. In this example, 8 pieces are selected. The coefficient of thermal expansion of the expansion petal 4 is determined by the material of the part, the material of the mold, and the processing temperature. In this example, the part being processed is TA15, 720℃, and the main material of the mold is silicon molybdenum ductile iron. Therefore, the coefficient of thermal expansion is selected as 0.996. The height of expansion petal 4 is composed of the height of the blank and the height of the fourth inclined plane 42. The third inclined plane 41 and the first inclined plane 32 of the cone 3 are matched, while the fourth inclined plane 42 and the second inclined plane 21 of the top plate 2 are matched. The fourth inclined plane 42 is one of the keys to realizing the contraction of expansion petal 4. By being pushed upward by the top plate 2, expansion petal 4 will slide downward and towards the axis due to its own weight, thereby realizing the contraction of expansion petal 4. The larger the angle between the fourth inclined plane 42 and the top plate 2, the smoother the sliding of the expansion petal 4. However, the height between the expansion petal 4 and the top plate 2 will also increase. If the angle is too small, sliding will not be possible. A 30° angle is usually chosen. 0 ~80 0 In this example, considering the equipment height and the actual mold height, a 30mm mold is selected. 0 The guide groove is U-shaped instead of T-shaped to prevent the expansion flap from getting stuck due to thermal expansion and contraction. The size of the expansion flap gap is selected as 28mm according to the size of the raw material.

[0027] 2. The cone angle of cone 3 is generally 5°. 0 ~30 0 Between these two values, a larger cone angle results in greater friction and easier self-locking, while a smaller cone angle leads to a longer stroke and increases the mold height. In this example, a 15mm cone angle is selected. 0 The cone angle and cone surface are designed with a first inclined plane of 32° to increase the contact area and reduce wear. Figure 7 .

[0028] 3. The top plate 2 adopts the design of the second inclined plane 21, such as... Figure 8 In conjunction with the expansion valve 4, this is one of the keys to the expansion valve 4 achieving self-weight contraction.

[0029] 4. The guide key 8 adopts a cuboid design instead of the traditional T-shaped key design. This provides smooth guidance for the expansion flap 4 while avoiding jamming caused by thermal expansion and contraction. It is also a key factor in achieving automatic retraction of the expansion flap 4. Figure 9 .

[0030] 5. Adjusting piece 7 is used to adjust the diameter of expansion flap 4, thereby adjusting the external dimensions of the part. Usually, 10 to 50 mm is selected according to the required adjustment amount. In this example, 20 mm is selected.

[0031] 6. Insert 6 is used for scribing. For asymmetrical rotating bodies requiring angular positioning, it allows for scribing while hot, facilitating angular positioning in the next process. Insert 6 is mounted on the upper end of the expansion flap 4 near the upper template 5 using the third screw 14. Figure 10 There is a raised ridge on the right side of the insert 6, which is used for engraving lines.

[0032] 7. When the cross-section of the rotating body is relatively complex or there are bosses or other surfaces on the rotating body, it is only necessary to install the die outside the expansion petal 4. However, it is necessary to consider that the part cannot be stuck on the die. If necessary, an avoidance groove can be opened to facilitate material removal.

[0033] (2) Making a pickup cart: such as Figure 2 The retrieval cart consists of a frame 15, a push rod 16, an electric lift 17, and a hook 18. The push rod 16 is placed on a rectangular support rod (a frame with rectangular holes). The two ends of the rectangular support rod are guided by pulleys to ensure that the push rod 16 can extend and retract freely. The rectangular support rod and the tray of the electric lift 17 are connected by bearings for easy free rotation. The hook 4 can be adjusted by sliding on the crossbeam according to the size of the part and is locked by the screw at the top. The frame 15 is equipped with heat insulation plates according to the actual situation for heat insulation during high-temperature part retrieval, which are not shown in the figure.

[0034] (3) Preparation of raw material: Based on the size of the part, after reserving a certain allowance and bulging amount, prepare the initial rotating body unfolding material. Taking two welds as an example, such as Figure 3 Then, the part is formed into an initial rotating body through processes such as bending and welding. To facilitate part removal, two lifting lugs need to be placed symmetrically on the rotating body. These lugs can be cut directly during blanking or welded on after the initial rotating body is formed. Figure 4 .

[0035] (4) Parts machining: Figure 2 After the thermal expansion mold is heated to the predetermined temperature, the ejector rod passes through the through hole on the lower template 1 to lift the top plate 2 and shrink the expansion petal 4. The part is sent in by the part picker and placed on the expansion petal 4. The top plate 2 is slowly lowered, allowing the expansion petal 4 to move down freely and expand. The part is tightened and the top plate 2 is lowered to the bottom (in contact with the adjusting plate 7 or the lower template 1). After keeping it at the temperature for a certain period of time according to the process requirements, the upper template 5 (which has a central hole to avoid the cone 3) is used to press the expansion petal 4 down to the bottom (in contact with the top plate 2). Then the mold is opened, the ejector rod lifts the top plate 2, and the expansion petal 4 automatically shrinks under the action of gravity. The part is taken out by the part picker and placed in the designated position. The next part is processed repeatedly.

[0036] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A thermal expansion mold, characterized in that, include: The lower template (1) has through holes for lifting the top rod; The cone (3) is installed on the upper end face of the lower template (1). The outer surface of the cone (3) includes a cylindrical surface (31) and a plurality of first inclined planes (32) located above the cylindrical surface (31). The plurality of first inclined planes (32) are centrally symmetrically distributed with the axis of the cylindrical surface (31) as the center. The outer diameter formed by the upper end of the plurality of first inclined planes (31) is smaller than the outer diameter formed by the lower end of the plurality of first inclined planes (31). A guide key (8) is installed on the first inclined plane (31). The guide key (8) is in the shape of a cuboid. The top plate (2) is an annular part, which is fitted onto the cylindrical surface (31) of the cone (3) through the inner annular hole of the annular part to form a sliding fit with the cylindrical surface (31). The upper end surface of the top plate (2) includes multiple second inclined planes (21). The multiple second inclined planes (21) are centrally symmetrically distributed with the axis of the inner annular hole of the annular part as the center. The outer diameter formed by the lower end of the multiple second inclined planes (21) is smaller than the outer diameter formed by the upper end of the multiple second inclined planes (21). The expansion flap (4) has a surface including an expansion surface on the outer side, a third inclined plane (41) on the inner side, a guide groove, and a fourth inclined plane (42) at the lower end. The third inclined plane (41) and the first inclined plane (31) form a planar sliding fit, the guide groove and the guide key (8) form a sliding fit, the cross section of the guide groove is U-shaped, and the fourth inclined plane (42) and the second inclined plane (21) form a planar sliding fit. Upper template (5), which is located above the expansion petal (4).

2. The thermal expansion mold according to claim 1, characterized in that: It also includes an insert (6) which is mounted on the expansion flap (4) and has a raised ridge on its outer surface for pressing out as an angular marker on the surface of the part.

3. The thermal expansion mold according to claim 1, characterized in that: It also includes an adjustment piece (7), which is installed between the top plate (2) and the lower template (1). The outer diameter of the expansion flap (4) is adjusted by changing the thickness of the adjustment piece (7).

4. The thermal expansion mold according to claim 1, characterized in that: The top plate (2), cone (3) and expansion flap (4) are made of medium silicon molybdenum ductile iron.

5. A thermal expansion mold according to claim 1, characterized in that: The number of the inflatable lobes (4) is 4 to 16; The planar sliding engagement angle between the third inclined plane (41) and the first inclined plane (31) is 30° to 80°; The cone angle of the first inclined plane (32) is 5° to 30°.

6. The thermal expansion mold according to claim 1, characterized in that: A guide key mounting groove is provided on the first inclined plane (31), and the guide key (8) is installed in the guide key mounting groove by the first screw (9); Bolts (10) are installed on the circumferential surface of the upper template (5); The cone (3) is mounted on the lower template (1) by a cylindrical pin (11) and a second screw (12); Lifting bolts (13) are installed on the lower template (1).

7. A rapid machining method for thermally expandable parts, characterized in that, include: Step 1, preparing raw material: After retaining a certain allowance and expansion amount based on the final size of the part, unfold it to obtain the unfolded material for thermal expansion of the part. Then, the unfolded material is rolled and welded to form an initial rotating body. The end face of the initial rotating body is provided with lifting lugs for picking up the part. Step 2: Heat the thermal expansion mold as described in claim 1 to a predetermined temperature, and lift the top plate (2) upwards using the push rod. The top plate (2) drives the expansion petals (4) to move closer to the cone (3), reducing the expansion diameter composed of multiple expansion petals (4). The initial rotating body is fitted into multiple expansion petals (4). The push rod descends, and the top plate (2) moves down accordingly. Multiple expansion petals (4) fall under their own weight, thereby expanding the expansion diameter until the initial rotating body is fully expanded. The top plate (2) moves down to the bottom and is kept warm for a period of time. Then, the upper template (5) is driven down to the bottom. The top plate (2) is lifted upwards using the push rod, reducing the expansion diameter composed of multiple expansion petals (4). The completed thermal expansion part is then removed.

8. A rapid machining method for thermally expandable parts according to claim 7, characterized in that: In step one, the lifting lugs are either pre-reserved on the unfolded material or welded after the initial rotating body is formed.

9. A rapid machining method for thermally expandable parts according to claim 7, characterized in that: In step two, a retrieval cart is used to remove the parts. The retrieval cart includes: The frame (15) has rollers installed at its lower end; An electric lifter (17) is mounted on the upper end of the frame (15); Push rod (16), which is slidably mounted on electric lifter (17), and has a crossbeam at the end of push rod (16); Hooks (18), at least two of the hooks (18) are mounted on the crossbeam of the push rod (16), and the spacing between the hooks (18) is adjustable.

10. A rapid machining method for thermally expandable parts according to claim 7, characterized in that: In step two, when the final rotating cross-sectional shape of the bulging part is complex, before heating the thermal expansion mold to the predetermined temperature, the concave mold corresponding to the rotating cross-sectional shape is first installed on the outside of the bulging petal (4).

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