Pressureless sintering forming die and forming method for impact cylinder

Abstract

The application discloses a pressureless sintering forming die and forming method of a bearing cylinder, and belongs to the technical field of powder metallurgy sintering dies. The positioning base plate of the die is embedded in the bottom wall of the bottom die, a centering spindle is inserted into the center hole of the bottom wall, rectangular bearing spray sides and wedge-shaped bearing spray sides are respectively inserted into the spray side ports on the two sides, and hard alloy blocks are attached to the surfaces of the two spray sides. The die core is inserted into the top end of the centering spindle, and the outer surface of the die core is spaced apart and attached with polycrystalline diamond. The bottom of the double-ear plate is bonded and positioned with the wedge-shaped bearing spray side, and the upper part is attached with the die core. The warehouse plate circular ring is arranged on the top of the die core, and the die sleeve is arranged on the bottom die. During forming, the material is uniformly distributed through assembly, multiple filling and vibration, the warehouse plate circular ring is removed, and then pressureless sintering is carried out. After sintering, the external components are removed, the internal graphite components are removed through drilling, turning or razor removal, and the lower part of the film sand body ear plate is crushed and removed. The application realizes integrated forming of the multi-cavity bearing cylinder, and has the characteristics of high positioning precision, good wear resistance and convenient demolding.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy sintering mold technology, specifically to a pressureless sintering mold for a hydraulic impactor bearing cylinder, and a forming method for achieving integrated sintering of the bearing cylinder using the mold. Background Technology

[0002] The impact cylinder is a key component in a hydraulic impactor. Serving as a guide cavity for the high-speed reciprocating motion of the piston / impact hammer, it contains multiple internal chambers in addition to a nozzle on its end face. Figure 1 and Figure 2 As shown. Under long-term high-speed friction working conditions, the impact cylinder needs to have high wear resistance, impact resistance and dimensional accuracy at the same time.

[0003] Currently, the conventional manufacturing process for impact cylinders involves using high-strength alloy steel and processing it through heat treatment, rough and finish machining, and cold inlay of hard alloy strips. However, this traditional process has the following prominent problems:

[0004] First, because the cylinder has multiple cavities and complex shapes, especially irregular holes and multi-step internal cavity structures, conventional machining methods are difficult to achieve one-piece molding. It often needs to be processed separately and then assembled, which not only involves many processes, but also makes it difficult to guarantee the coaxiality and positional accuracy between the cavities.

[0005] Secondly, under long-term high-speed friction conditions, the inner wall of the alloy steel impact cylinder is prone to severe wear. When lubrication fails, the impact hammer piston and the inner cavity are easily damaged or even seized, seriously affecting the service life and operational reliability of the impactor. In addition, the alloy steel body is also prone to oxidation and corrosion under humid or corrosive conditions.

[0006] Third, traditional processes require multiple complex and costly machining steps, such as deep hole machining and irregular hole machining, resulting in long production cycles, low material utilization, and are not conducive to mass production and low-cost manufacturing.

[0007] To address the aforementioned technical issues, it is necessary to develop a new type of mold and molding process that can achieve integrated molding of multiple cavities in a punching cylinder, in order to simplify the production process and improve the precision and overall performance of the product. Summary of the Invention

[0008] In view of this, the present invention provides a pressureless sintering molding die and molding method for a bearing cylinder, aiming to solve the above-mentioned technical problems.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A pressureless sintering mold for a bearing cylinder, used to achieve the sintering and forming of the bearing cylinder of a hydraulic impactor, comprising: The bottom mold has a positioning pad embedded in its inner cavity bottom wall. The positioning pad has a central insertion hole at its center. Spray-bearing square insertion ports are formed on both sides of the positioning pad and on both sides of the central insertion hole. Slots for the plate are formed along both sides of the positioning pad. A centering shaft is inserted into the central insertion hole. A rectangular spray-bearing square and a wedge-shaped spray-bearing square are respectively inserted into the two spray-bearing square insertion ports. The outer surface of the rectangular spray-bearing square and the lower outer surface of the wedge-shaped spray-bearing square are used to attach hard alloy blocks. Through-plates are inserted into the two slots for the plate. The mold core has a countersunk hole on its bottom surface that fits into the top of the centering shaft, and the bottom surface of the mold core abuts against the top surface of the rectangular spraying block; the outer surface of the mold core is used for intermittently laying polycrystalline diamond. The double ear plate has its bottom part bonded and positioned to the top surface of the wedge-shaped spray bearing. The lower part of the double ear plate is made of coated sand material, and the upper double ear window is made of high-strength dense graphite. The upper double ear window is attached to the outer surface of the mold core. A bin plate ring is sleeved on the top of the mold core, and its bottom end face abuts against the top surface of the upper double ear window of the double ear plate. A mold sleeve is fitted onto the bottom mold. The inner diameter of the mold sleeve is the same as the inner diameter of the bottom mold. The inner wall of the mold sleeve is in contact with the outer walls of the two through-hole plates and forms a gap with the outer wall of the annular plate for the filling of the unpressurized tire powder.

[0010] Through the above technical solution, this invention achieves integrated pressureless sintering of the multi-cavity punching cylinder by using a composite structural design of a bottom mold, positioning pad, rectangular and wedge-shaped spraying blocks, a through-hole plate, a mold core, double ear plates, a plate ring, and a mold sleeve. This eliminates the need for multiple complex processes such as deep hole machining and irregular hole machining in traditional processes, significantly shortening the production cycle and reducing manufacturing costs. By applying hard alloy blocks to the surfaces of the rectangular and wedge-shaped spraying blocks and spacing polycrystalline diamonds on the outer surface of the mold core, the sintered punching cylinder... The working surface of the cavity has extremely high hardness and wear resistance, effectively solving the problems of wear, scoring and seizing that traditional alloy steel punching cylinders are prone to under long-term high-speed friction conditions. At the same time, the double-ear plate split design is used. The lower part of the double-ear plate is made of coated sand material. The characteristic of the coated sand reducing strength after sintering makes it easy to demold. With the coaxial clearance fit between the centering shaft and the positioning pad, and the close fit and positioning between the double ear windows on the upper part of the double ear plate and the mold core, the coaxiality and positional accuracy between the cavities are effectively guaranteed, improving the dimensional consistency and yield of sintered products.

[0011] Preferably, in the pressureless sintering molding die for the above-mentioned bearing cylinder, the rectangular bearing plate is an elongated rectangular structure, and the wedge-shaped bearing plate is integrally composed of a bottom rectangular structure and an upper wedge-shaped structure.

[0012] Preferably, in the pressureless sintering mold of the above-mentioned bearing cylinder, the hard alloy block on the rectangular bearing plate has the same height as the rectangular bearing plate, and the hard alloy block on the wedge-shaped bearing plate has the same height as the rectangular structure of the wedge-shaped bearing plate, and the upper part is rounded.

[0013] Preferably, in the pressureless sintering mold of the above-mentioned impact cylinder, there is a gap between the lower part of the double ear plate and the outer wall of the mold core.

[0014] Preferably, in the pressureless sintering mold of the above-mentioned impact cylinder, the top inner wall surface of the through-hole plate is in contact with the outer wall surface of the plate ring.

[0015] Preferably, in the pressureless sintering molding die for the above-mentioned impact cylinder, the top wall thickness of the die sleeve is less than the bottom wall thickness, so that the inner wall of the die sleeve forms a funnel-shaped structure, and the funnel-shaped structure is located above the through-hole plate.

[0016] Preferably, in the pressureless sintering molding die for the above-mentioned impact cylinder, the two end faces of the die core are provided with annular hollow grooves along the axial direction.

[0017] Preferably, in the pressureless sintering molding die for the above-mentioned impact cylinder, the outer diameter of the die sleeve is larger than the outer diameter of the bottom die, and the bottom of the die sleeve has an insertion countersunk hole that is interference-fitted with the bottom die.

[0018] This invention also discloses a pressureless sintering molding method for a bearing cylinder, based on the aforementioned mold, comprising the following steps: S1: Insert the positioning pad into the inner wall of the bottom cavity of the bottom mold with interference fit, then insert the centering shaft into the center hole of the positioning pad, insert the rectangular spraying square and the wedge-shaped spraying square with hard alloy block attached into the two spraying square sockets of the positioning pad respectively, and insert the through plate into the slot of the positioning pad. S2: Polycrystalline diamonds are intermittently laid on the outer surface of the mold core, and the bottom countersunk hole of the mold core is inserted into the top of the centering shaft so that the bottom surface of the mold core abuts against the top surface of the rectangular spraying block. S3: Bond the bottom of the double ear plate to the top surface of the wedge-shaped spray container and position it, and make the upper double ear window of the double ear plate fit with the outer surface of the mold core to achieve coaxial positioning; S4: Place the bin plate ring on the top of the mold core, so that the bottom end face of the bin plate ring abuts against the top surface of the upper double ear window of the double ear plate. Then place the mold sleeve on the bottom mold, so that the inner wall of the mold sleeve fits against the outer wall of the two through bin plates and forms a gap with the outer wall of the bin plate ring. S5: Fill the mold with unpressurized tire powder through the gap between the mold sleeve and the silo plate ring. After filling, remove the silo plate ring. S6: The assembled and filled mold is sent into the sintering furnace for pressureless sintering. After sintering, the mold sleeve, mold core, positioning pad, centering shaft, through chamber plate, rectangular spraying square, wedge-shaped spraying square and upper double ear window of the double ear plate are removed. The lower part of the double ear plate can be crushed into powder and removed by taking advantage of the characteristic that the strength of the coated sand material is reduced after sintering.

[0019] Through the above technical solutions, this invention integrates mold assembly, powder filling, pressureless sintering, and step-by-step demolding into a single process flow, achieving one-step molding of complex multi-cavity structures for punch cylinders. This eliminates the need for multiple cumbersome processes such as deep hole machining and irregular hole machining in traditional machining, significantly shortening the production cycle and reducing processing costs. By dividing the pressureless mold body powder into multiple fillings and coordinating with vibration or shaking to even out the material, the uniformity and fullness of the powder filling in complex cavities are effectively guaranteed, thereby improving the uniformity of the structure and the consistency of the dimensions of the sintered products. At the same time, by utilizing the characteristic that the strength of the coated sand material decreases significantly after high-temperature sintering, the lower part ear plate can be easily crushed and demolded, solving the technical problem of difficult demolding of irregular cavities, effectively avoiding damage to the products caused by forced demolding, and improving the yield and demolding efficiency.

[0020] Preferably, in the above-mentioned pressureless sintering molding method for a bearing cylinder, the pressureless body powder is filled in multiple batches, and is mixed with vibration or shaking to achieve uniformity and fullness of the overall filling.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a pressureless sintering molding die and molding method for a bearing cylinder, which has the following beneficial effects: 1. This invention achieves integrated pressureless sintering molding of multi-cavity punch cylinders by using a composite structure design of bottom mold, positioning pad, mold core, double ear plate, chamber plate ring and mold sleeve, as well as the embedded cooperation of rectangular spray receiving square, wedge-shaped spray receiving square and through chamber plate. This eliminates many complex processes such as deep hole processing and irregular hole processing in traditional processes, significantly shortens the production cycle and reduces manufacturing costs.

[0022] 2. This invention applies hard alloy blocks to the surface of rectangular and wedge-shaped injection blocks and applies polycrystalline diamonds at intervals to the outer surface of the mold core, so that the working surface of the inner cavity of the fired injection cylinder has extremely high hardness and wear resistance. This effectively solves the problem that traditional alloy steel injection cylinders are prone to wear, scoring and seizing under long-term high-speed friction conditions, and greatly extends the service life of the injection cylinder.

[0023] 3. The present invention adopts a split structure with double ear plates. The lower split ear plate is made of coated sand material, and the upper double ear window is made of high-strength dense graphite. Taking advantage of the characteristic that the strength of coated sand is significantly reduced after high-temperature sintering, it can be easily removed by crushing. This effectively solves the technical problem of difficult demolding of complex irregular cavities and improves demolding efficiency and yield.

[0024] 4. This invention achieves coaxial positioning between the mold core and each spraying unit by cooperating with the centering shaft and the center insertion hole of the positioning pad, and by fitting the upper double ear window of the double ear plate with the outer surface of the mold core. This ensures the coaxiality and positional accuracy between the cavities of the punching cylinder, and effectively improves the dimensional consistency of the sintered products.

[0025] 5. The present invention effectively balances thermal stress during sintering by using annular hollow grooves on both ends of the mold core, preventing deformation or cracking of the mold core due to high-temperature thermal expansion, and extending the service life of the mold.

[0026] 6. This invention ensures the uniformity and fullness of the powder filling inside the mold by dividing the pressureless mold body powder into multiple fillings and coordinating with vibration or shaking to achieve uniformity, thereby improving the uniformity of the structure and the consistency of the performance of the sintered product; at the same time, the pressureless sintering process under vacuum or inert gas protective atmosphere avoids product oxidation and further improves product quality. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 The attached figure is a structural schematic diagram of the impact cylinder provided by the present invention from a bottom view angle; Figure 2 The attached figure is a top view of the structure of the impact cylinder provided by the present invention; Figure 3 The attached figure is a schematic diagram of the external structure of the pressureless sintering molding die for the impact cylinder provided by the present invention; Figure 4 The attached figure is a cross-sectional view of the pressureless sintering molding die for the impact cylinder provided by the present invention; Figure 5 The attached figure is a cross-sectional view of the pressureless sintering molding die for the impact cylinder provided by the present invention from another angle; Figure 6 The attached figure is a top view of the pressureless sintering molding die for the impact cylinder provided by the present invention. Figure 7The attached figure is provided by the present invention. Figure 3 The diagram shows the structure after the mold sleeve has been removed. Figure 8 The attached figure is provided by the present invention. Figure 7 The diagram shows the structure after the bottom formwork has been removed. Figure 9 The attached figure is provided by the present invention. Figure 8 The diagram shows the structure after the through-type silo panel has been removed. Figure 10 The attached figure is provided by the present invention. Figure 9 The diagram shows the structure after the bin plate ring has been removed. Figure 11 The attached figure is provided by the present invention. Figure 10 The diagram shows the structure after the double-ear plate has been removed. Figure 12 The attached figure is provided by the present invention. Figure 11 The diagram shows the structure after the mold core has been removed. Figure 13 The attached figure is a schematic diagram of the positioning pad provided by the present invention; Figure 14 The attached figure is a schematic diagram of the structure of the mold core provided by the present invention; Figure 15 The attached figure is a schematic diagram of the connection between the wedge-shaped spray nozzle and the double ear plate provided by the present invention.

[0029] in: 1-Punching cylinder; 2-Bottom mold; 3-Mold core; 4-Double ear plate; 5-Block plate ring; 6-Mold sleeve; 7-Positioning pad; 31-Counterhead hole on the bottom surface; 32-Polycrystalline diamond; 33-Annular hollow groove; 41-Lower part ear plate; 42-Upper part double ear window; 61-Funnel-shaped structure; 62-Interlocking countersunk hole; 71-Center socket; 72-Spraying square socket; 73-Blouse plate slot; 74-Centering shaft; 75-Rectangular spraying square; 76-Wedge-shaped spraying square; 77-Hard alloy block; 78-Through-through lobe plate. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: See appendix Figure 3 To be continued Figure 15 This invention discloses a pressureless sintering molding die for a hydraulic impactor, which is used to achieve pressureless sintering and integrated molding of the hydraulic impactor's cylinder 1.

[0032] As attached Figure 3 and attached Figure 4 As shown, the mold mainly includes a bottom mold 2, a mold core 3, a double-ear plate 4, a chamber plate ring 5, a mold sleeve 6, and a positioning pad 7. Among them, the bottom mold 2 serves as the base of the entire mold, and the positioning pad 7 is embedded in the bottom wall of its inner cavity. The positioning pad 7 and the bottom wall of the inner cavity of the bottom mold 2 are interference fit to ensure that the positioning pad 7 does not shift during the sintering process.

[0033] See appendix Figure 13 The positioning pad 7 has a central insertion hole 71 at its center, into which a centering shaft 74 is inserted. The centering shaft 74 and the central insertion hole 71 are coaxially clearance fitted, with a tolerance range of 0.05mm to 0.08mm. On both sides of the central insertion hole 71, the positioning pad 7 has spray-bearing square insertion ports 72, into which a rectangular spray-bearing square 75 and a wedge-shaped spray-bearing square 76 are respectively inserted. On both sides of the positioning pad 7, there are plate slots 73, into which through-plates 78 are respectively inserted.

[0034] The rectangular spray-bearing square 75 has an overall elongated rectangular structure, while the wedge-shaped spray-bearing square 76 is integrally composed of a rectangular bottom structure and an upper wedge-shaped top structure. Both the outer surface of the rectangular spray-bearing square 75 and the lower outer surface of the wedge-shaped spray-bearing square 76 are covered with cemented carbide blocks 77, which are used to improve wear resistance. The cemented carbide blocks 77 on the rectangular spray-bearing square 75 have the same height as the rectangular spray-bearing square 75, and the cemented carbide blocks 77 on the wedge-shaped spray-bearing square 76 have the same height as the rectangular structure of the wedge-shaped spray-bearing square 76, with rounded corners at the top to avoid stress concentration.

[0035] As attached Figure 4 and attached Figure 14 As shown, the bottom surface of the mold core 3 has a countersunk hole 31, which is inserted into the top of the centering shaft 74, so that the mold core 3 and the centering shaft 74 are coaxially positioned. The bottom surface of the mold core 3 abuts against the top surface of the rectangular bearing 75. Polycrystalline diamond 32 is applied to the outer surface of the mold core 3 at intervals. The polycrystalline diamond 32 is used to improve the wear resistance of the inner hole of the sintered bearing cylinder. Annular hollow grooves 33 are also formed on both end faces of the mold core 3 along the axial direction. The annular hollow grooves 33 are used to balance the sintering stress during the sintering process and prevent the mold core 3 from deforming or cracking due to thermal stress.

[0036] See appendix Figure 4 and attached Figure 15The bottom of the double-ear plate 4 is bonded and positioned to the top surface of the wedge-shaped spray receiving square 76 using an adhesive. The double-ear plate 4 is a split-type composite structure, including a lower separate ear plate 41 and an upper double-ear window 42. The lower separate ear plate 41 is made of coated sand material, and the upper double-ear window 42 is made of high-strength dense graphite; the two are sintered into a single unit at a temperature of 200℃~260℃. The upper double-ear window 42 is fitted to the outer surface of the mold core 3 to achieve coaxial positioning between the mold core 3 and the wedge-shaped spray receiving square 76. There is a gap between the lower separate ear plate 41 of the double-ear plate 4 and the outer wall of the mold core 3.

[0037] The silo plate ring 5 is fitted on the top of the mold core 3, and the bottom end face of the silo plate ring 5 abuts against the top surface of the upper double ear window 42 of the double ear plate 4. The top inner wall surface of the through silo plate 78 fits against the outer wall surface of the silo plate ring 5 to achieve radial positioning between the through silo plate 78 and the silo plate ring 5.

[0038] See appendix Figure 4 and attached Figure 5 The mold sleeve 6 is fitted onto the bottom mold 2. The outer diameter of the mold sleeve 6 is larger than that of the bottom mold 2, and a countersunk hole 62 is formed at the bottom of the mold sleeve 6. The countersunk hole 62 is interference-fitted with the bottom mold 2 to achieve a fixed connection between the mold sleeve 6 and the bottom mold 2. The inner wall diameter of the mold sleeve 6 is the same as that of the inner cavity of the bottom mold 2, and the inner wall of the mold sleeve 6 fits against the outer wall of the two through-hole plates 78, forming a gap with the outer wall of the plate ring 5 for the filling of the unpressurized tire powder.

[0039] As attached Figure 4 As shown, the top wall thickness of the mold sleeve 6 is less than the bottom wall thickness, which forms a funnel-shaped structure 61 on the inner wall of the mold sleeve 6. The funnel-shaped structure 61 is located above the through-hole plate 78. The funnel-shaped structure 61 facilitates the filling of unpressurized powder, allowing the powder to flow smoothly into the gap between the mold sleeve 6 and the plate ring 5.

[0040] Example 2: Based on the pressureless sintering molding die for the punching cylinder provided in Embodiment 1 above, the present invention also discloses a pressureless sintering molding method for the punching cylinder, specifically including the following steps: S1: Insert the positioning pad 7 into the inner cavity bottom wall of the bottom mold 2 with an interference fit of 0.02mm to 0.05mm. Then, insert the centering shaft 74 into the center insertion hole 71 of the positioning pad 7. The centering shaft 74 and the center insertion hole 71 are coaxially clearance fits with a tolerance range of 0.05mm to 0.08mm. Insert the rectangular spray receiving square 75 and the wedge-shaped spray receiving square 76, which are pre-attached with hard alloy blocks 77, into the two corresponding spray receiving square insertion slots 72 of the positioning pad 7. The rectangular spray receiving square 75 and the wedge-shaped spray receiving square 76 are respectively interference fits with the corresponding spray receiving square insertion slots 72. Insert the through-hole plate 78 into the plate slot 73 of the positioning pad 7. The through-hole plate 78 and the plate slot 73 are coaxially clearance fits with a tolerance range of 0.05mm to 0.08mm.

[0041] S2: Polycrystalline diamond 32 is laid alternately on the outer surface of the mold core 3. The spacing of the polycrystalline diamond 32 is determined according to the wear resistance requirements of the actual inner hole of the punching cylinder. Then, the bottom countersunk hole 31 of the mold core 3 is inserted into the top of the centering shaft 74, so that the bottom surface of the mold core 3 abuts against the top surface of the rectangular punching block 75. The centering shaft 74 and the bottom countersunk hole 31 are interference fit, with an interference amount of 0.02mm to 0.05mm.

[0042] S3: The bottom of the double ear plate 4 (i.e. the bottom of the lower body ear plate 41) is bonded and positioned to the top surface of the wedge-shaped spraying container 76 with adhesive, and the upper double ear window 42 of the double ear plate 4 is attached to the outer surface of the mold core 3, thereby achieving coaxial positioning between the mold core 3 and the wedge-shaped spraying container 76.

[0043] S4: Place the silo plate ring 5 on top of the mold core 3, so that the bottom end face of the silo plate ring 5 abuts against the top surface of the upper double ear window 42 of the double ear plate 4. Then, place the mold sleeve 6 on the bottom mold 2, so that the insertion countersunk hole 62 at the bottom of the mold sleeve 6 is interference-fitted with the bottom mold 2, and at the same time, make the inner wall of the mold sleeve 6 fit against the outer wall of the two through silo plates 78, and form a gap with the outer wall of the silo plate ring 5 for filling powder.

[0044] S5: Fill the mold with unpressurized tire powder through the gap between the mold sleeve 6 and the hopper ring 5. During filling, the unpressurized tire powder is filled in multiple times, and after each filling, it is vibrated or shaken to even out the material, thereby achieving uniformity and fullness of the overall filling. After filling is completed, remove the hopper ring 5.

[0045] S6: The assembled and filled mold is sent into the sintering furnace for pressureless sintering at a temperature of 1000℃~1600℃ in a vacuum or inert gas atmosphere for 2h~6h. After sintering, the mold sleeve 6, mold core 3, positioning pad 7, centering shaft 74, through chamber plate 78, rectangular spraying square 75, wedge-shaped spraying square 76, and the upper double ear window 42 of the double ear plate 4 are removed. The lower part of the double ear plate 4, the separate ear plate 41, utilizes the characteristic that the strength of the coated sand material is significantly reduced after sintering. It is crushed into powder using tools and removed from the mold, thus achieving complete demolding of the punching cylinder 1.

[0046] Example 3: In a preferred embodiment of the present invention, the materials of the various components of the mold are selected as follows: The mold sleeve 6, bottom mold 2, positioning pad 7, mold core 3, and upper double-ear window 42 of the double-ear plate 4 are all made of high-density graphite material. The bending strength of this high-density graphite material is not less than 45MPa, and the maximum withstand temperature is not less than 1650℃, so as to meet the application requirements of pressureless sintering temperature of 1000℃~1600℃.

[0047] The lower part of the double ear plate 4, the ear plate 41, is made of coated sand material. The strength of the coated sand is significantly reduced after high-temperature sintering, making it easy to crush and remove after sintering.

[0048] The hard alloy blocks 77 attached to the surfaces of the rectangular and wedge-shaped spray bearing blocks 75 and 76 are made of hard alloy material with a hardness of not less than HRA85 to ensure the wear resistance of the working surface of the cylinder cavity.

[0049] The polycrystalline diamond 32 that is intermittently laid on the outer surface of the mold core 3 has better wear resistance than cemented carbide, which can further improve the wear life of the inner hole of the impact cylinder.

[0050] Example 4: In a preferred embodiment of the present invention, the bin plate ring 5 is fitted on the top of the mold core 3 before loading, and its bottom end face abuts against the top surface of the upper double ear window 42 of the double ear plate 4. At the same time, the top inner wall surface of the through bin plate 78 is in contact with the outer wall surface of the bin plate ring 5, thereby achieving radial positioning of the through bin plate 78.

[0051] During loading, the unpressurized tire powder is poured into the gap between the mold sleeve 6 and the bin plate ring 5 through the funnel-shaped structure 61 of the mold sleeve 6. After loading is completed, since the bin plate ring 5 is positioned only by the fit and is not fixedly connected to other parts, the bin plate ring 5 can be easily pulled out and removed from the top of the mold core 3.

[0052] It should be noted that the silo plate ring 5 is used to position the through silo plates 78 on both sides. When the unpressurized tire powder is filled to the height of the silo plate ring 5, the unpressurized tire powder can ensure the stable position of the through silo plate 78. Therefore, the silo plate ring 5 can be removed and the empty space of the removed silo plate ring 5 can be filled with unpressurized tire powder.

[0053] Example 5: See appendix Figure 14 In a preferred embodiment of the present invention, annular perforated grooves 33 are formed on both end faces of the mold core 3 along the axial direction. During the pressureless sintering process, the entire mold is heated to 1000℃~1600℃, and the components will undergo different degrees of thermal expansion due to their different coefficients of thermal expansion. The annular perforated grooves 33 provide the mold core 3 with a certain amount of deformation clearance space when heated, which can effectively absorb and balance the thermal stress generated during the sintering process, prevent the mold core 3 from cracking or breaking due to stress concentration, thereby ensuring the service life of the mold core 3 and the forming accuracy of the stamping cylinder products.

[0054] Example 6: After sintering, the punch cylinder 1 product is encased inside the mold. Demolding is performed in the following sequence: First, remove the mold sleeve 6 from the bottom mold 2. Since the mold sleeve 6 and the bottom mold 2 are interference-fitted through the countersunk hole 62, the bottom mold 2 can be pressed out of the mold sleeve 6 using a press. Then, separate the bottom mold 2 from the positioning pad 7 and pull out the two through-hole plates 78. At this point, the mold sleeve 6, bottom mold 2, through-hole plates 78, and positioning pad 7 have been disassembled as a reusable mold assembly.

[0055] Then, the mold components that cannot be directly removed and are encased inside the punching cylinder 1 are destructively removed. Specifically, the mold core 3, centering shaft 74, rectangular nozzle 75, and wedge-shaped nozzle 76 are all encased in the matrix material after sintering and cannot be completely removed. They need to be drilled and broken apart one by one before removal. Among them, after the centering shaft 74 is drilled through, positioning graphite material is used to weld and fill the gap, restoring the structure of that position to be consistent with the surrounding matrix material.

[0056] Regarding the double-ear plate 4, its upper double-ear window 42 is made of high-strength dense graphite, which retains high strength after sintering. However, because it is embedded inside the corresponding cavity of the receiving cylinder 1, it cannot be directly removed and must be removed manually with a razor. The lower double-ear plate 41 is made of coated sand material. During the sintering process, it experienced high temperatures of 1000℃ to 1600℃. The binder of the coated sand material has decomposed, and its strength has been significantly reduced. After crushing it with a metal rod, the debris can be poured out from the corresponding cavity of the receiving cylinder 1.

[0057] In summary, all graphite components embedded inside the stamping cylinder 1 (including the mold core 3, centering shaft 74, rectangular spray nozzle 75, wedge-shaped spray nozzle 76, and upper double-ear window 42) are removed by turning, drilling, or manual shaving, ultimately obtaining a sintered product of the stamping cylinder 1 with a complete internal cavity structure. Although this demolding method damages some mold components, it effectively ensures that the complex multi-cavity structure of the stamping cylinder can be completely formed after sintering, avoiding cracking or deformation of the product caused by forced demolding.

[0058] It should be noted that since the mold core 3 originally has an annular hollow groove 33, during the drilling and crushing process, the hollow groove structure can serve as a stress release area, reducing the impact of drilling on the surrounding body material, which is beneficial to ensuring the integrity and surface quality of the inner wall of the impact cylinder 1.

[0059] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0060] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pressureless sintering mold for a bearing cylinder, used to achieve the sintering of the bearing cylinder (1) of a hydraulic impactor, characterized in that, include: The bottom mold (2) has a positioning pad (7) embedded in the bottom wall of its inner cavity. The positioning pad (7) has a central insertion hole (71) at the center of its surface. The positioning pad (7) has a spray-bearing square insertion port (72) on both sides of the central insertion hole (71). The positioning pad (7) has a silo plate slot (73) on both sides of its edge. A centering shaft (74) is inserted into the central insertion hole (71). A rectangular spray-bearing square (75) and a wedge-shaped spray-bearing square (76) are inserted into the two spray-bearing square insertion ports (72), respectively. The outer surface of the rectangular spray-bearing square (75) and the lower outer surface of the wedge-shaped spray-bearing square (76) are used to apply hard alloy blocks (77). A through silo plate (78) is inserted into the two silo plate slots (73). The mold core (3) has a countersunk hole (31) on its bottom surface that is inserted into the top of the centering shaft (74), and the bottom surface of the mold core (3) abuts against the top surface of the rectangular spraying block (75); the outer surface of the mold core (3) is used to lay polycrystalline diamond (32) at intervals. Double ear plate (4), the bottom of the double ear plate (4) is bonded and positioned to the top surface of the wedge-shaped spraying block (76), the lower part of the double ear plate (41) is made of coated sand material, the upper double ear window (42) is made of high-strength dense graphite, and the upper double ear window (42) is attached to the outer surface of the mold core (3); The bin plate ring (5) is sleeved on the top of the mold core (3), and the bottom end face abuts against the top surface of the upper double ear window (42) of the double ear plate (4); A mold sleeve (6) is fitted onto the bottom mold (2). The inner wall diameter of the mold sleeve (6) is the same as the inner cavity diameter of the bottom mold (2). The inner wall of the mold sleeve (6) is in contact with the outer walls of the two through-hole plates (78) and forms a gap with the outer wall of the plate ring (5) for the filling of the pressureless tire body powder.

2. The pressureless sintering molding die for a punching cylinder according to claim 1, characterized in that, The rectangular spray container (75) has an overall elongated rectangular structure, and the wedge-shaped spray container (76) is composed of a rectangular structure at the bottom and a wedge-shaped structure at the top.

3. The pressureless sintering molding die for a punching cylinder according to claim 2, characterized in that, The hard alloy block (77) on the rectangular spray receiving square (75) has the same height as the rectangular spray receiving square (75), the hard alloy block (77) on the wedge-shaped spray receiving square (76) has the same height as the rectangular structure of the wedge-shaped spray receiving square (76), and the upper part of the wedge-shaped spray receiving square (76) is rounded.

4. The pressureless sintering molding die for a punching cylinder according to claim 1, characterized in that, There is a gap between the lower part of the double ear plate (41) and the outer wall of the mold core (3).

5. The pressureless sintering molding die for a punching cylinder according to claim 1, characterized in that, The top inner wall surface of the through-hole plate (78) is in contact with the outer wall surface of the plate ring (5).

6. The pressureless sintering molding die for a punching cylinder according to claim 1, characterized in that, The top wall thickness of the mold sleeve (6) is less than the bottom wall thickness, so that the inner wall of the mold sleeve (6) forms a funnel-shaped structure (61), which is located above the through-hole plate (78).

7. The pressureless sintering molding die for a punching cylinder according to claim 1, characterized in that, The two ends of the mold core (3) are provided with annular hollow grooves (33) along the axial direction.

8. The pressureless sintering mold for a punching cylinder according to claim 1, characterized in that, The outer diameter of the mold sleeve (6) is larger than the outer diameter of the bottom mold (2), and the bottom of the mold sleeve (6) has an insertion countersunk hole (62) that is interference fit with the bottom mold (2).

9. A pressureless sintering forming method for a punching cylinder, based on the mold described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Insert the positioning pad (7) into the inner wall of the bottom cavity of the bottom mold (2) with interference fit, then insert the centering shaft (74) into the center insertion hole (71) of the positioning pad (7), insert the rectangular spraying square (75) and the wedge-shaped spraying square (76) with hard alloy block (77) attached into the two spraying square insertion holes (72) of the positioning pad (7) respectively, and insert the through plate (78) into the plate slot (73) of the positioning pad (7); S2: Polycrystalline diamond (32) is laid at intervals on the outer surface of the mold core (3), and the bottom countersunk hole (31) of the mold core (3) is inserted into the top of the centering shaft (74) so ​​that the bottom surface of the mold core (3) abuts against the top surface of the rectangular spraying block (75). S3: Bond the bottom of the double ear plate (4) to the top surface of the wedge-shaped spray nozzle (76) and make the upper double ear window (42) of the double ear plate (4) fit with the outer surface of the mold core (3) to achieve coaxial positioning; S4: Place the bin plate ring (5) on the top of the mold core (3) so that the bottom end face of the bin plate ring (5) abuts against the top surface of the upper double ear window (42) of the double ear plate (4). Then place the mold sleeve (6) on the bottom mold (2) so that the inner wall of the mold sleeve (6) fits against the outer wall of the two through bin plates (78) and forms a gap with the outer wall of the bin plate ring (5). S5: Fill the mold with unpressurized tire powder through the gap between the mold sleeve (6) and the silo plate ring (5), and remove the silo plate ring (5) after the filling is completed; S6: The assembled and filled mold is sent into the sintering furnace for pressureless sintering. After sintering, the mold sleeve (6), mold core (3), positioning pad (7), centering shaft (74), through chamber plate (78), rectangular spraying square (75), wedge-shaped spraying square (76) and upper double ear window (42) of double ear plate (4) are removed. The lower part of the double ear plate (4) is pulverized into powder and removed by utilizing the characteristic that the strength of the coated sand material decreases after sintering.

10. A pressureless sintering forming method for a punching cylinder according to claim 9, characterized in that, The non-pressurized tire powder is filled in multiple stages, and is mixed with vibration or shaking to achieve uniformity and fullness of the overall filling.

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