Double-layer sliding bearing powder metallurgy forming device and forming process

Abstract

The invention discloses a powder metallurgy forming device for a double-layer sliding bearing. The powder metallurgy forming device comprises a pressing die and a positioning device. The pressing die comprises an upper punch, a die core, a lower inner punch, a lower outer punch, a female die, a lower blocking cylinder and an elastic positioning piece. The positioning device comprises an upper positioning plate, a lower supporting plate and a plurality of positioning units; the lower blocking cylinder is placed on the upper end face of the lower supporting plate. The lower part of the small-diameter section and the large-diameter section of the mold core are positioned in the lower blocking cylinder; an inner hole of the lower inner punch is matched with the outer circle of the small-diameter section of the die core; the lower outer punch is located on the upper portion of the lower blocking cylinder. The upper section of the excircle of the female die is matched with the inner hole of the upper positioning plate; and the inner hole is matched with the excircle of the upper middle part of the small-diameter section of the lower outer punch. According to the invention, two different kinds of metal powder can be pressed into the inner layer and the outer layer of the sliding bearing respectively, and the inner layer and the outer layer with different physical properties are pressed into a whole to form a compact and uniform double-layer sliding bearing blank.

Description

Technical Field

[0001] The invention relates to the field of metal forming and powder metallurgy technology, and in particular to a double-layer sliding bearing powder metallurgy forming device and a forming process. Technical Background

[0002] Sliding bearings are mostly prepared by powder metallurgy process. Due to their simple structure, strong load-bearing capacity, stable operation and wide adaptability, they are widely used in transmission machinery and equipment in the fields of automobiles, engineering machinery, precision machinery, etc. When sliding bearings work under complex working conditions or boundary lubrication, the bearing materials often have problems such as insufficient hardness and strength, poor load-bearing capacity, etc., which inevitably cause severe wear on the inner surface of the sliding bearing, thereby shortening its service life. In order to improve the strength of the inner surface of the sliding bearing, reduce the friction between the shaft and the inner surface of the sliding bearing, and reduce its wear, the main measures taken at this stage include: using materials with better performance for the entire sliding bearing, or electroplating a layer of alloy with higher hardness on its inner surface. The above two methods have greatly improved the strength of the inner surface of the sliding bearing, reduced wear, and extended its service life, but the overall use of high-performance materials is costly, and the process of electroplating alloys on the inner surface is relatively complex, costly, and causes great pollution to the environment. The structure of sliding bearings is annular, and powder metallurgy technology can be used to easily prepare single-layer sliding bearings. Although the academic community believes that double-layer sliding bearings have obvious performance advantages, the powder metallurgy forming technology of double-layer sliding bearings has become a technical shortcoming in the industry due to the complexity of the pressing mold and the forming process. In the past, the inner and outer layers of bearing materials were prepared separately, and then the inner and outer layers were formed together by mechanical interlocking to form a double-layer sliding bearing. However, the bonding ability of the interface between the two layers of material is poor, which limits the improvement of the performance of the double-layer sliding bearing. Therefore, it is urgent to develop a relatively simple and low-cost powder metallurgy forming technology to manufacture double-layer sliding bearings to meet the higher performance requirements of mechanical transmission equipment under complex working conditions. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a double-layer sliding bearing powder metallurgy forming device, which can press two different metal powders into the inner layer and outer layer of the sliding bearing respectively, and press the inner and outer layers with two different physical properties into one body to form a dense and uniform double-layer sliding bearing blank. At the same time, the present invention provides a double-layer sliding bearing powder metallurgy forming process.

[0004] The present invention discloses a double-layer sliding bearing powder metallurgy forming device, which comprises a pressing die and a positioning device; the pressing die comprises an upper die punch, a die core, a lower inner die punch, a lower outer die punch, a female die, a lower retaining cylinder, and an elastic positioning sheet; the positioning device comprises an upper positioning plate and a plurality of positioning units of a lower support plate; the upper positioning plate and the lower support plate are respectively provided with a plurality of positioning holes at corresponding upper and lower positions, and the upper positioning plate and the lower support plate are connected by a plurality of positioning units; the lower retaining cylinder is placed on the upper end surface of the lower support plate; the lower part of the small diameter section of the die core and the large diameter section are both located in the lower retaining cylinder, and the lower end surface of the large diameter section contacts the upper end surface of the lower support plate; the lower inner die punch is provided with a plurality of positioning holes at corresponding upper and lower positions of the upper positioning plate and the lower support plate ... is connected by a plurality of positioning units; the lower retaining cylinder is placed on the upper end surface of the lower support plate; the lower part of the small diameter section of the die core and the large diameter section are both located in the lower retaining cylinder, and the lower end surface of the large diameter section contacts the upper end surface of the lower support plate; the lower inner die punch is provided with a plurality of positioning holes at corresponding upper and lower positions of the upper positioning plate and the lower support plate is connected by a plurality of positioning units; the lower retaining cylinder is placed on the upper end surface of the lower support plate; the lower part of the small diameter section of the die core and the large diameter section are both located in the lower retaining cylinder, and the lower end surface of the large diameter section The inner hole of the die punch cooperates with the outer circle of the small diameter section of the die core, and the lower part and the large diameter section of the small diameter section of the lower inner die punch are both located in the lower retaining tube; the lower outer die punch is located in the upper part of the lower retaining tube, and its inner hole cooperates with the outer circle of the upper middle part of the small diameter section of the lower inner die punch; the upper section of the outer circle of the female die cooperates with the inner hole of the upper positioning plate, and its inner hole cooperates with the outer circle of the upper middle part of the small diameter section of the lower outer die punch; the outer circles of the die core and the lower inner die punch are both provided with two circumferentially symmetrically distributed grooves, the elastic positioning sheet is fixedly installed in the groove, and the movable section outside the elastic positioning sheet has an outward wedge-shaped protrusion; the axes of the die core, the lower inner die punch, the lower outer die punch, the female die, and the lower retaining tube coincide.

[0005] Furthermore, the core, the lower inner punch, the lower outer punch and the female die can achieve relative axial movement; the relative positions of the lower inner punch, the lower outer punch, the female die and the core form the required powder filling space between the four components; the upper punch performs stamping to press the bearing into shape.

[0006] Furthermore, the outer circle of the small straight section of the upper punch lower part matches with the inner hole of the female die, and the inner hole thereof matches with the outer circle of the small diameter section of the mold core.

[0007] Furthermore, the lower retaining cylinder is composed of two bilaterally symmetrical semi-cylindrical cylinders.

[0008] Furthermore, the outer circle of the large diameter section of the mold core matches with the inner hole of the lower stopper.

[0009] Furthermore, the outer circle of the large diameter of the lower inner die punch is slightly smaller than the inner hole of the lower retaining cylinder.

[0010] Furthermore, each positioning unit includes a guide column and a spring, and a plurality of positioning holes are evenly distributed at corresponding positions on the upper and lower positioning plates and the lower support plates; the guide column passes through the positioning hole of the lower support plate, the spring, and the positioning hole of the upper positioning plate, and the threaded section at the tail end is locked by a nut.

[0011] Furthermore, the positioning device also includes a clamping mechanism, which includes a circular ring, a screw propulsion mechanism, and multiple clamping units. The screw propulsion mechanism includes a screw, a propulsion block, a fixed block, a handle, and an anti-slip pin. Each clamping unit includes a threaded pin, a slider, a strip block, and a contact block. The propulsion block is connected to the small mounting block on the outer circle of the circular ring through a pin, the anti-slip pin passes through the upper end of the pin, and the fixed block is fixed to the lower end surface of the upper positioning plate. One end of the screw is screwed into the threaded hole of the propulsion block and then extends out, and the other end is matched with the inner hole of the fixed block and then extends out and is connected to the handle; a number of grooves are evenly opened along the circumferential direction between the upper and lower end surfaces of the circular ring, the slider is located in the groove and is hinged to the circular ring through a pin, the strip block passes through the slider, its inner end is connected to the contact block through a pin, and its outer end is connected to the pin at the lower end of the threaded pin, and the upper end of the threaded pin is threadedly connected to the small mounting block on the lower end surface of the upper positioning plate.

[0012] The invention discloses a powder metallurgy forming process for a double-layer sliding bearing: the pressing of the blank is divided into three processes: the filling and pre-pressing of the outer metal powder, the filling and pre-pressing of the inner metal powder, and the mixed forming and pressing of the inner and outer metal layers.

[0013] Furthermore, the molding process is specifically divided into five steps: ① Filling the outer layer powder: first, the lower end face of the lower outer die punch is in contact with the upper end face of the lower retaining cylinder. At this time, the distance between the upper end face of the lower outer die punch and the upper end face of the female die is d1; then, the upper end face of the lower inner die punch is flush with the upper end face of the female die. At this time, the elastic positioning piece installed in the groove of the mold core just pops out and supports the bottom of the lower inner die punch to prevent it from sliding down; then, the outer layer of metal powder is filled in the gap formed by the lower outer die punch, the lower inner die punch and the female die until the powder is filled and flush with the upper end face of the female die; ② Outer layer powder Prepressing: The external press drives the upper punch to move downward in the vertical direction to prepress the filled outer layer powder. During this process, the lower inner punch follows the upper punch and moves downward a distance d2; when the lower inner punch is pressed downward by external force, the elastic positioning piece in the groove of the mold core is squeezed and retracted into the groove to ensure the smooth downward movement of the lower inner punch; ③ Filling the inner layer powder: First, remove the upper punch above the prepressed outer layer powder from the female die; then move the lower outer punch upward until the upper end surface of the prepressed outer layer blank is flush with the upper end surface of the female die; then split the lower retaining cylinder and take it out to expose the lower inner die ④ Inner layer powder pre-pressing: the external press drives the upper die punch to move along the vertical direction, and the upper end face of the female die is flush with the upper end face of the female die. Move downward to pre-press the filled inner layer powder. During this process, the lower outer punch and the pre-pressed outer blank move downward a distance d2; when the lower outer punch moves downward by external force, the elastic positioning piece in the groove of the lower inner punch is compressed and retracts into the groove, ensuring the smooth downward movement of the lower outer punch; when the lower end face of the lower outer punch just contacts the upper end face of the lower retaining cylinder, the inner layer powder is pre-pressed; ⑤ Double-layer sliding bearing pressing and molding: continue to increase the external press pressure to make the upper punch continue to move downward, so that the outer blank and the inner blank are squeezed into one, forming a dense and uniform double-layer blank.

[0014] The advantages of the powder metallurgy forming device and forming process of the double-layer sliding bearing of the present invention are: 1. Through the coordination and relative position change of the lower outer die punch, the lower inner die punch, the female die and the die core in the mold, two different metal powders can be pressed into the inner and outer layers of the sliding bearing respectively, and the inner and outer layers with two different physical properties are pressed into one body to form a dense and uniform double-layer sliding bearing blank; 2. The adaptability of clamping and positioning of female dies with different outer diameters is improved by the clamping mechanism, and the production cost is reduced while ensuring the stability of pressing; 3. Elastic positioning plates are added to the die core and the lower inner die punch, and the rapidity and accuracy of positioning the lower inner die punch and the lower outer die punch at the required specific position are ensured without affecting the relative movement between the die core, the lower inner die punch, the lower outer die punch and the female die. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a three-dimensional diagram of the powder metallurgy forming device of the present invention.

[0016] Figure 2 This is a diagram of the positional relationship between the various parts of the pressing mold when the outer layer powder is loaded (excluding the upper punch).

[0017] Figure 3 This is a diagram showing the positional relationship between the various components of the pressing mold during pre-pressing of the outer layer powder (excluding the upper punch).

[0018] Figure 4 This is a cross-sectional view of the positional relationship between the various components of the pressing mold when the inner layer powder is loaded (excluding the upper punch).

[0019] Figure 5 This is a diagram showing the positional relationship between the various components of the pressing mold during pre-pressing of the inner layer powder (excluding the upper punch).

[0020] Figure 6 The three-dimensional clamping mechanism Figure 1 (Remove the upper positioning plate).

[0021] Figure 7 The three-dimensional clamping mechanism Figure 2 .

[0022] Figure 8 It is a partial enlarged cross-sectional view of the elastic positioning piece installed in the lower inner punch when it pops out.

[0023] Fig. 9 It is a partial enlarged cross-sectional view of the elastic positioning piece installed in the lower inner punch when it is retracted. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] from Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that the present invention is a double-layer sliding bearing powder metallurgy forming device, which includes a pressing mold 1 and a positioning device 2; the pressing mold 1 includes an upper punch 11, a mold core 12, a lower inner punch 13, a lower outer punch 14, a female mold 15, a lower retaining cylinder 16, and an elastic positioning plate 17; the positioning device 2 includes an upper positioning plate 21, a lower support plate 22, and a plurality of positioning units; the upper positioning plate 21 and the lower support plate 22 are respectively provided with a plurality of positioning holes at corresponding upper and lower positions, and the upper positioning plate 21 and the lower support plate 22 are connected by a plurality of positioning units; the lower retaining cylinder 16 is placed on the upper end surface of the lower support plate 22; the lower part of the small diameter section and the large diameter section of the mold core 12 are both located in the lower retaining cylinder 16, and the lower end surface of the large diameter section contacts the upper end surface of the lower support plate 22 ; The inner hole of the lower inner punch 13 cooperates with the outer circle of the small diameter section of the core 12, and the lower part and the large diameter section of the small diameter section of the lower inner punch 13 are both located in the lower retaining tube 16; the lower outer punch 14 is located in the upper part of the lower retaining tube 16, and its inner hole cooperates with the outer circle of the upper middle part of the small diameter section of the lower inner punch 13; the upper section of the outer circle of the female die 15 cooperates with the inner hole of the upper positioning plate 21, and its inner hole cooperates with the outer circle of the upper middle part of the small diameter section of the lower outer punch 14; the outer circles of the core 12 and the lower inner punch 13 are both provided with two circumferentially symmetrically distributed grooves, and the elastic positioning sheet 17 is fixedly installed in the groove, and the movable section outside the elastic positioning sheet 17 has an outward wedge-shaped protrusion; the axes of the core 12, the lower inner punch 13, the lower outer punch 14, the female die 15, and the lower retaining tube 16 coincide.

[0027] The present invention discloses a powder metallurgy forming device for a double-layer sliding bearing: a die core 12, a lower inner die punch 13, a lower outer die punch 14, and a female die 15 can realize relative axial movement; the relative positions of the lower inner die punch 13, the lower outer die punch 14, the female die 15, and the die core 12 form the required powder filling space between the four components; an upper die punch 11 performs stamping to press and form the bearing.

[0028] Among them, the elastic positioning piece 17 has a good elastic deformation and can be completely pressed into the groove under the action of external force: when the lower inner die punch 13 moves up to the desired position relative to the die core 12 and the lower outer die punch 14 moves up to the lower inner die punch 13, the elastic positioning piece 17 pops out, and the wedge-shaped protrusion on the elastic positioning piece 17 just supports the bottom of the lower inner die punch 13 or the lower outer die punch 14, which is convenient for the accurate and rapid positioning of the lower inner die punch 13 and the lower outer die punch 14 and prevents them from sliding down; when the lower inner die punch 13 moves down relative to the die core 12 and the lower outer die punch 14 moves down relative to the lower inner die punch 13 under external force, the elastic positioning piece 17 is squeezed by its own supporting parts and then retracts into the groove, allowing its own supporting parts to slide down smoothly.

[0029] In order to reduce the friction resistance when the supporting part moves downward and ensure that the supporting part can slide down smoothly, a proper amount of grease can be applied to the tip of the wedge-shaped protrusion of the elastic positioning piece 17. When the elastic force of the elastic positioning piece 17 weakens during long-term use and the positioning of the supporting part is misaligned, it is only necessary to remove the original elastic positioning piece and replace it with a new elastic positioning piece.

[0030] Example 2

[0031] from Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that the present invention is a double-layer sliding bearing powder metallurgy forming device: the outer circle of the small straight section at the lower part of the upper punch 11 matches with the inner hole of the female die 15, and its inner hole matches with the outer circle of the small diameter section of the core 12.

[0032] The upper punch 11 presses out the bearing during the pressing process through the cooperation of its outer circle and inner hole with the female die 15 and the die core 12.

[0033] Example 3

[0034] from Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that in the double-layer sliding bearing powder metallurgy forming device of the present invention, the lower retaining cylinder 16 is composed of two left-right symmetrical semi-cylindrical cylinders.

[0035] The functions of the lower retaining cylinder 16 are: 1. When the upper punch 11 presses the outer layer of metal powder, the lower end face of the large diameter section of the lower outer punch 14 will not move downward after contacting the upper end face of the lower retaining cylinder 16, thereby supporting the lower outer punch 14 and ensuring that the relative position of the lower outer punch 14 relative to the core 12 and the female die 15 does not change; 2. When the inner layer of metal powder needs to be installed, the lower retaining cylinder 16 can be easily disassembled and taken out from the positioning device 2 to expose the lower outer punch 13, thereby conveniently adjusting the relative position of the lower inner punch 13 relative to the female die 15 and the core 12. After adjusting the position of the lower inner punch 13, the lower retaining cylinder 16 can be reinstalled.

[0036] Example 4

[0037] from Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that in the powder metallurgy forming device for a double-layer sliding bearing of the present invention, the outer circle of the large diameter section of the mold core 12 is matched with the inner hole of the lower retaining cylinder 16 .

[0038] The outer circle of the large diameter section of the mold core 12 contacts the inner hole of the lower retaining tube 16 and the lower end surface of the large diameter section of the mold core 12 contacts the upper end surface of the lower support plate 22, which ensures the stability of the mold core 12 and further ensures the stability during the downward pressure molding.

[0039] Example 5

[0040] from Figure 2 , Figure 3 , Figure 4 , Figure 5 It can be seen that in the powder metallurgy forming device for a double-layer sliding bearing of the present invention, the outer circle of the large diameter of the lower inner die punch 13 is slightly smaller than the inner hole of the lower retaining cylinder 16 .

[0041] The outer circle of the large diameter of the lower inner die punch 13 is slightly smaller than the inner hole of the lower retaining cylinder 16 , which facilitates the up and down movement of the lower inner die punch 13 .

[0042] Example 6

[0043] from Figure 1 It can be seen that the present invention is a double-layer sliding bearing powder metallurgy forming device: each positioning unit includes a guide column 23 and a spring 24, and a plurality of positioning holes are evenly distributed at corresponding positions of an upper positioning plate 21 and a lower support plate 22; the guide column 23 passes through the positioning hole of the lower support plate 22, the spring 24, and the positioning hole of the upper positioning plate 21, and the threaded section at the tail end is locked by a nut.

[0044] The nut is tightened with the thread at the tail end of the guide column 23 to form a certain pre-pressure on the spring 24 to ensure the stability of the overall positioning device; when the upper positioning plate 21 moves downward along the guide column 23 under the push of external force, the spring 24 installed on the guide column 23 is compressed to produce a greater elastic force. When the external force acting on the upper positioning plate 21 is released, the upper positioning plate 21 can return to its initial position along the guide column 23 under the action of the elastic force of the spring 24.

[0045] Example 7

[0046] from Figure 1 , Figure 6 , Figure 7It can be seen that the present invention is a double-layer sliding bearing powder metallurgy forming device: the positioning device 2 also includes a clamping mechanism, the clamping mechanism includes a ring 251, a screw propulsion mechanism, and multiple clamping units, the screw propulsion mechanism includes a screw 255, a propulsion block 256, a fixed block 257, a handle 258, and an anti-drop pin 259, each clamping unit includes a threaded pin 250, a slider 252, a bar block 253, and a contact block 254; the propulsion block 256 is connected to the small mounting block on the outer circle of the ring 251 through a pin, the anti-drop pin 259 passes through the upper end of the pin, and the fixed block 257 is fixed on On the lower end surface of the upper positioning plate 21, one end of the screw rod 255 is screwed into the threaded hole of the push block 256 and then extends out, and the other end is matched with the inner hole of the fixing block 257 and then extends out to be connected to the handle 258; a number of grooves are evenly opened along the circumferential direction between the upper and lower end surfaces of the ring 251, the slider 252 is located in the groove and is hinged to the ring through a pin shaft, the strip block 253 passes through the slider 252, its inner end is connected to the contact block 254 through a pin shaft, and its outer end is connected to the pin shaft at the lower end of the threaded pin shaft 250, and the upper end of the threaded pin shaft 250 is threadedly connected to the small mounting block on the lower end surface of the upper positioning plate 21.

[0047] Different specifications of the double-layer sliding bearing will cause the outer diameter of the female mold 15 to change, and the aperture of the upper positioning plate 21 will also change. If the upper positioning plate is replaced, the manufacturing cost will increase. Therefore, the device of the present invention improves the adaptability to different outer diameters of the female mold 15 by adding a clamping mechanism, thereby reducing the manufacturing cost.

[0048] The working principle of the clamping mechanism is: rotating the handle 258 drives the screw 255 to rotate, thereby driving the ring 251 to rotate through the push block 256; the slider 252 rotates with the ring 251 on the one hand, and drives the bar block 253 to rotate toward the center of the ring 251 on the other hand, so that the contact block 254 contacts the outer circle of the female mold 15 to achieve positioning and clamping of the female mold 15, ensuring the stability of the mold during the entire pressing process. When the female mold 15 or the mold needs to be replaced, the handle 258 is rotated in the opposite direction to separate the contact block 254 from the female mold 15.

[0049] The number of clamping units is preferably three clamping units evenly distributed along the circumference of the ring, so that three contact blocks 254 can clamp the female mold 15 with three claws, ensuring the stability of clamping and preventing the female mold 15 from deforming due to uneven force. The contact surface between the contact block 254 and the outer circle of the female mold 15 is preferably two planes with a specific obtuse angle.

[0050] Example 8

[0051] The powder metallurgy forming process of the double-layer metal sliding bearing of the present invention: the pressing of the blank is divided into three sets of processes: filling and pre-pressing of the outer metal powder, filling and pre-pressing of the inner metal powder, and mixed forming and pressing of the inner and outer metal layers.

[0052] It should be noted that there is no restriction on the order of the inner layer metal powder filling and pre-pressing process and the outer layer metal powder filling and pre-pressing process. The outer layer metal powder can be filled and pre-pressed first, and then the inner layer metal powder; or the inner layer metal powder can be filled and pre-pressed first, and then the outer layer metal powder. The two pressing methods only differ in the order in which the inner and outer layers are pre-pressed.

[0053] Example 9

[0054] The powder metallurgy forming method of the double-layer sliding bearing of the present invention is specifically divided into 5 steps:

[0055] ① Filling the outer layer powder: First, the lower end face of the lower outer die punch 14 is in contact with the upper end face of the lower retaining cylinder 16. At this time, the distance between the upper end face of the lower outer die punch 14 and the upper end face of the female die 15 is d1; then, the upper end face of the lower inner die punch 13 is flush with the upper end face of the female die 15. At this time, the elastic positioning piece 17 installed in the groove of the mold core 12 just pops out and supports the bottom of the lower inner die punch 13 to prevent it from sliding down; then fill the outer layer metal powder into the gap formed by the lower outer die punch 14, the lower inner die punch 13 and the female die 15 until the powder is filled and flush with the upper end face of the female die 15; the size of the distance d1 is determined by the height h of the female die 15, d1 = h*(2 / 3~3 / 4); Figure 2 As shown,

[0056] ② Pre-pressing of outer layer powder: The external press drives the upper punch 11 to move downward in the vertical direction to pre-press the filled outer layer powder. During this process, the lower inner punch 13 follows the upper punch 11 and moves downward by a distance d2; when the lower inner punch 13 is pressed downward by an external force, the elastic positioning piece 17 in the groove of the mold core 12 is squeezed and retracted into the groove to ensure the smooth downward movement of the lower inner punch 13; the size of the distance d2 is determined by the height h of the female mold 15, d2 = h*(1 / 4~2 / 5); Figure 3 As shown,

[0057] ③ Filling the inner layer powder: first, remove the upper die punch 11 above the pre-pressed outer layer powder from the female die 15; then move the lower outer die punch 14 upward until the upper end surface of the pre-pressed outer layer blank is flush with the upper end surface of the female die 15; then split and take out the lower retaining cylinder 16 to expose the lower inner die punch 13, and move the lower inner die punch 13 downward so that its lower end surface contacts the upper end surface of the large diameter section of the die core 12. At this time, the upper end surface of the lower inner die punch 13 forms a distance d1 with the upper end surface of the female die 15; at the same time, the elastic positioning piece installed in the groove of the lower inner die punch 13 pops out and supports the bottom of the lower outer die punch 14 to prevent it from sliding down; then, reassemble the lower retaining cylinder 16 into a whole in the original position, and finally fill the inner layer metal powder in the gap formed by the lower outer die punch 14, the lower inner die punch 13, the die core 12 and the outer layer blank until the powder is filled and flush with the upper end surface of the female die 15; Figure 4 As shown,

[0058] ④ Pre-pressing of inner layer powder: The external press drives the upper die punch 11 to move downward in the vertical direction to pre-press the filled inner layer powder. During this process, the lower outer die punch 14 and the pre-pressed outer layer blank move downward by a distance d2; when the lower outer die punch 14 moves downward by external force, the elastic positioning piece 17 in the groove of the lower inner die punch 13 is compressed and retracted into the groove to ensure the smooth downward movement of the lower outer die punch; when the lower end face of the lower outer die punch 14 just contacts the upper end face of the lower retaining cylinder 16, the inner layer powder is pre-pressed; Figure 5 As shown,

[0059] ⑤ Double-layer sliding bearing pressing and forming: Continue to increase the external press pressure, so that the upper die punch 11 continues to move downward, so that the outer layer blank and the inner layer blank are squeezed into one, forming a dense and uniform double-layer blank.

[0060] When the pressing die completes the pressing of the double-layer sliding bearing blank, first pull the upper punch 11 upward from the female die 15; then apply external force to press the upper positioning plate 21 downward, driving the female die 15 to move downward in the vertical direction relative to the mold core 12, the lower inner punch 13, and the lower outer punch 14 until the double-layer blank is completely exposed, and the pressed blank is extracted from the mold core 12; remove the external force acting on the upper positioning plate 21, so that the upper positioning plate 21 and the female die 15 return to their initial positions under the action of the elastic force of the spring 24, and prepare for the pressing of the next double-layer metal sliding bearing blank.

[0061] The advantages of the powder metallurgy forming device and forming process of the double-layer sliding bearing of the present invention are: 1. Through the coordination and relative position change of the lower outer die punch, the lower inner die punch, the female die and the die core in the mold, two different metal powders can be pressed into the inner and outer layers of the sliding bearing respectively, and the inner and outer layers with two different physical properties are pressed into one body to form a dense and uniform double-layer sliding bearing blank; 2. The adaptability of clamping and positioning of female dies with different outer diameters is improved by the clamping mechanism, and the production cost is reduced while ensuring the stability of pressing; 3. Elastic positioning plates are added to the die core and the lower inner die punch, and the rapidity and accuracy of positioning the lower inner die punch and the lower outer die punch at the required specific position are ensured without affecting the relative movement between the die core, the lower inner die punch, the lower outer die punch and the female die.

[0062] The molding device and molding process of the present invention can flexibly match different powders in the gap between the inner and outer layers according to the actual working conditions, so as to press out a double-layer sliding bearing blank with different physical properties to meet the requirements of different application conditions. The powder here can be a metal powder or a non-metallic powder. For example, ordinary metal powder is pressed to form the outer layer of the sliding bearing, and metal powder with high strength, good oil immersion and excellent lubrication performance is pressed to form the inner layer of the sliding bearing, and finally a double-layer sliding bearing blank with excellent inner surface wear resistance, longer service life and low production cost is obtained. At the same time, the present invention is not limited to pressing double-layer sliding bearing blanks, as long as it is a double-layer sleeve-type part, it can be pressed by the device and process of the present invention.

[0063] The double-layer sliding bearing powder metallurgy forming device of the present invention has a simple structure, a convenient operation process, a low manufacturing cost, low energy consumption during use and no pollution to the environment.

Claims

1. A double-layer sliding bearing powder metallurgy forming device, characterized by: It comprises a pressing die (1) and a positioning device (2); the pressing die (1) comprises an upper die punch (11), a die core (12), a lower inner die punch (13), a lower outer die punch (14), a female die (15), a lower retaining tube (16), and an elastic positioning sheet (17); the positioning device (2) comprises an upper positioning plate (21), a lower support plate (22), and a plurality of positioning units; the upper positioning plate (21) and the lower support plate (22) are respectively provided with a plurality of positioning holes at corresponding upper and lower positions, and the upper positioning plate (21) and the lower support plate (22) are connected via a plurality of positioning units; the lower retaining tube (16) is placed on the upper end surface of the lower support plate (22); the lower part of the small diameter section and the large diameter section of the die core (12) are both located in the lower retaining tube (16), and the lower end surface of the large diameter section contacts the upper end surface of the lower support plate (22); the lower inner die punch (13) The inner hole of the lower die punch (13) is matched with the outer circle of the small diameter section of the die core (12), and the lower part and the large diameter section of the small diameter section of the lower inner die punch (13) are both located in the lower retaining tube (16); the lower outer die punch (14) is located in the upper part of the lower retaining tube (16), and its inner hole is matched with the outer circle of the upper middle part of the small diameter section of the lower inner die punch (13); the upper section of the outer circle of the female die (15) is matched with the inner hole of the upper positioning plate (21), and its inner hole is matched with the outer circle of the upper middle part of the small diameter section of the lower outer die punch (14); the outer circles of the die core (12) and the lower inner die punch (13) are both provided with two grooves distributed symmetrically in the circumferential direction, and the elastic positioning piece (17) is fixedly installed in the groove, and the movable section outside the elastic positioning piece (17) has an outward wedge-shaped protrusion; the axes of the die core (12), the lower inner die punch (13), the lower outer die punch (14), the female die (15) and the lower retaining tube (16) coincide.

2. The molding device according to claim 1, characterized in that: The die core (12), the lower inner die punch (13), the lower outer die punch (14) and the female die (15) can realize relative axial movement; the relative positions of the lower inner die punch (13), the lower outer die punch (14), the female die (15) and the die core (12) form a required powder filling space between the four components; the upper die punch (11) performs stamping to press and form the bearing.

3. The molding device according to claim 1 is characterized in that: The outer circle of the small straight section at the lower part of the upper die punch (11) matches with the inner hole of the female die (15), and the inner hole matches with the outer circle of the small diameter section of the die core (12).

4. The molding device according to claim 1 is characterized in that: The lower retaining cylinder (16) is composed of two left-right symmetrical semi-cylindrical cylinders.

5. The molding device according to claim 1, characterized in that: The outer circle of the large diameter section of the mold core (12) matches the inner hole of the lower stopper cylinder (16).

6. The molding device according to claim 1, characterized in that: The outer circle of the large diameter of the lower inner die punch (13) is slightly smaller than the inner hole of the lower retaining cylinder (16).

7. The molding device according to claim 1, characterized in that: Each positioning unit comprises a guide column (23) and a spring (24); a plurality of positioning holes are evenly distributed at corresponding positions on the upper and lower positions of the upper positioning plate (21) and the lower support plate (22); the guide column (23) passes through the positioning hole of the lower support plate (22), the spring (24), and the positioning hole of the upper positioning plate (21); and the threaded section at the rear end thereof is locked by a nut.

8. The molding device according to claim 7, characterized in that: The positioning device (2) also includes a clamping mechanism, which includes a circular ring (251), a screw propulsion mechanism, and a plurality of clamping units. The screw propulsion mechanism includes a screw rod (255), a propulsion block (256), a fixing block (257), a handle (258), and an anti-drop pin (259). Each clamping unit includes a threaded pin shaft (250), a slider (252), a strip block (253), and a contact block (254). The propulsion block (256) is connected to a small mounting block on the outer circle of the circular ring (251) via a pin shaft, the anti-drop pin (259) passes through the upper end of the pin shaft, and the fixing block (257) is fixed to the upper positioning plate (21). On the lower end surface, one end of the screw rod (255) is screwed into the threaded hole of the propulsion block (256) and then extends out, and the other end is matched with the inner hole of the fixing block (257) and then extends out to be connected with the handle (258); a plurality of grooves are evenly opened along the circumferential direction between the upper and lower end surfaces of the circular ring (251), the slider (252) is located in the groove and is hinged to the circular ring through a pin shaft, the strip block (253) passes through the slider (252), the inner end of which is connected to the contact block (254) through a pin shaft, and the outer end of which is connected to the pin shaft at the lower end of the threaded pin shaft (250), and the upper end of the threaded pin shaft (250) is threadedly connected to the small mounting block on the lower end surface of the upper positioning plate (21).

9. A double-layer sliding bearing powder metallurgy forming process, characterized by: The pressing of the blank is divided into three processes: filling and pre-pressing of the outer layer metal powder, filling and pre-pressing of the inner layer metal powder, and mixed molding and pressing of the inner and outer metal layers.

10. The molding process according to claim 9, characterized in that: It is divided into five steps: ① Filling the outer layer powder: First, make the lower end face of the lower outer punch contact with the upper end face of the lower retaining cylinder. At this time, the distance between the upper end face of the lower outer punch and the upper end face of the female die is d1; then make the upper end face of the lower inner punch flush with the upper end face of the female die. At this time, the elastic positioning piece installed in the groove of the mold core just pops out and supports the bottom of the lower inner punch to prevent it from sliding down; Then fill the outer layer of metal powder into the gap formed by the lower outer punch, the lower inner punch and the female die until the powder is filled flush with the upper end surface of the female die; ② Pre-pressing of outer layer powder: The external press drives the upper punch to move downward in the vertical direction to pre-press the filled outer layer powder. During this process, the lower inner punch follows the upper punch and moves downward by a distance d2. When the lower inner punch is pressed downward by external force, the elastic positioning piece in the groove of the die core is squeezed and retracted into the groove to ensure the smooth downward movement of the lower inner punch. ③ Filling the inner layer powder: First, remove the upper die punch above the pre-pressed outer layer powder from the female die; then move the lower outer die punch upward until the upper end surface of the pre-pressed outer layer blank is flush with the upper end surface of the female die; then split and remove the lower retaining cylinder to expose the lower inner die punch, and move the lower inner die punch downward so that its lower end surface contacts the upper end surface of the large diameter section of the die core. At this time, the upper end surface of the lower inner die punch forms a distance d1 with the upper end surface of the female die; at the same time, the elastic positioning piece installed in the groove of the lower inner die punch pops out, supporting the bottom of the lower outer die punch to prevent it from sliding down; Subsequently, the lower retaining cylinder is reassembled as a whole in the original position, and finally the inner layer metal powder is filled into the gap formed by the lower outer die punch, the lower inner die punch, the die core and the outer layer blank until the powder is filled and flush with the upper end surface of the female die; ④ Pre-pressing of inner layer powder: The external press drives the upper punch to move downward in the vertical direction to pre-press the filled inner layer powder. During this process, the lower outer punch and the pre-pressed outer layer blank move downward by a distance d2; when the lower outer punch moves downward by external force, the elastic positioning in the groove of the lower inner punch is compressed and retracts into the groove, ensuring the smooth downward movement of the lower outer punch; when the lower end face of the lower outer punch just contacts the upper end face of the lower retaining tube, the inner layer powder is pre-pressed. ⑤ Double-layer sliding bearing pressing and forming: Continue to increase the external press pressure, so that the upper punch continues to move downward, so that the outer layer blank and the inner layer blank are squeezed into one, forming a dense and uniform double-layer blank.

Images