Powder metallurgy process for generator adjusting arm

Abstract

The present application relates to the technical field of powder metallurgy, and discloses a powder metallurgy process for a generator adjusting arm, which comprises the following steps: S1: Fe-Cu-C series powder metallurgy materials are mixed for 30 minutes by a 500 kg double-cone mixer; S2: a 200T forming press is used to press a friction core rod by using a one-under-two structure mold, the pressing force is 50 KN, a powder pressing piece is obtained, the powder pressing piece is one-time formed with an ø8 hole and an ø12 hole, the density of the powder pressing piece is 6.9-7.0 g / m3; S3: the sintering process temperature is 1120 DEG C; S4: carburizing heat treatment is performed, the carbon potential is 0.6%, the quenching temperature is 850 DEG C, and the quenching oil temperature is 60 DEG C. The process can overcome the problem of the tensile strength of the adjusting arm caused by the pores in the powder metallurgy which are difficult to completely eliminate, meet the use requirements, and ensure that the height tolerance is within 0.2 mm by using the powder metallurgy, so that secondary processing is not needed, and the product shape consistency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of powder metallurgy, and particularly relates to a powder metallurgy process for a generator adjusting arm. BACKGROUND

[0002] The adjusting arm product has a complex shape, and a HT250 casting process is used to manufacture a blank in the early stage, and cutting processing is used to ensure the drawing and use requirements. The production efficiency is low, and the processing and manufacturing cost is high.

[0003] The generator adjusting arm realizes its function by adjusting the belt tension of the driving wheel, and the generator adjusting arm is a long and narrow workpiece. After the end of the adjusting arm is stressed, the load carried by the adjusting arm is doubled under the action of the long force arm. Therefore, if the adjusting arm is processed by using the powder metallurgy mode, the tensile strength needs to meet the use requirements.

[0004] Please refer to Figure 1 、 Figure 2 The width of the two rod bodies of the adjusting arm is about 7mm, the thickness is about 15.5mm, the rod body shape is approximately cuboid, and the overall length is about 81mm. The shape is long and narrow. The shape causes the placement and sintering pose of the adjusting arm after compression molding to be difficult to control. The ø12 hole tube of the compression molded adjusting arm is cylindrical, the ø12 hole tube cannot be in contact with the contact surface horizontally and inclined to one end, at this time, the contact area of the ø12 hole tube and the contact surface is a point. The ø12 hole tube before sintering has low strength and is easy to break and deform, so that the size and specification after sintering do not meet the requirements. SUMMARY

[0005] The purpose of the present application is to provide a powder metallurgy process for a generator adjusting arm to solve the problems raised in the background art.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A powder metallurgy process for a generator adjusting arm, comprising:

[0008] S1: Fe-Cu-C powder metallurgy material is mixed by a 500kg double-cone mixer for 30 minutes;

[0009] S2: a 200T forming press is used, a one-under-two structure is used on the mold, a friction core rod is pressed, the pressing force is 50KN, a powder pressing piece is obtained, the powder pressing piece is one-time formed with an ø8 hole and an ø12 hole, and the density of the powder pressing piece is 6.9-7.0g / m³;

[0010] S3: the sintering process temperature is 1120℃, sintering is performed for 25-30 minutes, and then cooling is performed;

[0011] S4: carburizing heat treatment, carbon potential 0.6%, quenching temperature 850℃, quenching oil temperature 60℃, holding time 90 minutes, tempering temperature 180℃, tempering time 120 minutes;

[0012] S5: The ø7 hole and two ø3 holes are processed by drilling process, and the inner wall of the hole is processed by finishing process to obtain a sintered part.

[0013] As a further solution of the present invention: it includes step S3A: using a mesh belt sintering furnace to sinter under an ammonia decomposition protective atmosphere, with a preheating zone temperature of 750°C and a high temperature zone temperature of 1120°C, sintering in the high temperature zone for 25-30 minutes and then entering cooling, and a mesh belt speed of 100 mm / min.

[0014] As a further solution of the present invention: it includes step S3B: using a box furnace for sintering, tilting the powder compact, and supporting the corner ends of the tube in the powder compact with the angle limit rod and the torsion support limit rod respectively, and sintering the powder compact twice.

[0015] As a further solution of the present invention: in step S3B, the center line of the long side of the powder compact is the center line of the workpiece, the line connecting the centers of the angle limiting rod and the torsion support limiting rod is the limiting oblique line, and the inclination direction of the workpiece center line to the vertical line is opposite to the inclination direction of the limiting oblique line to the vertical line.

[0016] As a further solution of the present invention: in step S3B, the horizontal spacing between the angle limiting rod and the torsion support limiting rod is smaller than the narrowest end width of the powder compact.

[0017] As a further solution of the present invention: one end of the powder compact having the ø7 hole is located above the torsion support limit rod.

[0018] As a further solution of the present invention, a center rod is inserted into the ø12 hole of the powder compact, and a plurality of powder compacts are inserted into the center rod.

[0019] As a further solution of the present invention, the pretreatment step of step S5 is also included: a vibration polishing machine uses stainless steel filigree abrasive to polish the sintered part for 20 minutes, and an ultrasonic cleaning machine is used for cleaning for 30 minutes at a frequency of 40-50 Hz and the medium is hydrocarbon.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This powder metallurgy process for generator adjustment arms overcomes the problem of difficult-to-eliminate internal porosity in powder metallurgy, which can severely impact the arm's tensile strength. The resulting arm achieves an ultimate tensile strength of 620-700 MPa and a surface hardness of HRC35-HRC45, meeting operational requirements. Furthermore, the powder metallurgy process guarantees a height tolerance of within 0.2 mm. Both ø8 and ø12 holes are formed in one go, eliminating the need for secondary processing. This ensures high product appearance consistency and reduces processing costs by approximately 30%.

[0022] Secondly, for the powder compact of the generator adjustment arm, the arm's support function is achieved using angle limit rods and torsion support limit rods. After sintering, the generator adjustment arm shrinks in volume. The arm is affected by the gravity of the irregularly shaped portion, causing it to rotate about the torsion support limit rod. The angle limit rod slides with the straight rod to maintain stability. This increases the contact surface between the protective atmosphere and the generator adjustment arm during sintering, overcomes the sintering volume change of the generator adjustment arm, and enables dynamic fixation and rapid batch removal, facilitating processing and circulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a processing drawing for a generator adjustment arm;

[0025] Figure 2 A processing drawing for another angle of the generator adjustment arm;

[0026] Figure 3 A schematic diagram of a box-type furnace sintering process for a powder metallurgy process for a generator adjustment arm;

[0027] Figure 4 A schematic diagram of the posture of a generator adjusting arm during sintering in a box-type furnace in a powder metallurgy process for the generator adjusting arm;

[0028] Figure 5 This is a schematic diagram of the overall posture of a powder metallurgy process for a generator adjustment arm during sintering in a box furnace;

[0029] Figure 6 This is a schematic diagram of the overall posture of the generator adjustment arm placed horizontally;

[0030] In the figure: 100, limit oblique line; 200, workpiece center line; 1, angle limit rod; 2, torsion support limit rod; 3, center rod. DETAILED DESCRIPTION

[0031] See also Figures 1-6 :

[0032] Example 1:

[0033] The original product is made of HT250 and its mechanical properties are tensile strength: 250Mpa, hardness: HB209.

[0034] This embodiment includes the following steps:

[0035] S1: According to the MPIF35 standard, Fe-Cu-C powder metallurgy materials are selected, corresponding to the brand FC-0208, and mixed in a 500 kg double cone mixer for 30 minutes. The process adopts molding-sintering-heat treatment;

[0036] S2: Use a 200T molding press with a mold structure of two upper and lower parts, a friction core rod, and a pressing force of 50KN to obtain powder pressed parts. The powder pressed parts are formed into ø8 holes and ø12 holes in one step, and the density of the powder pressed parts is 6.9-7.0g / m³;

[0037] S3A: Sintering is carried out in a mesh belt sintering furnace under an ammonia decomposition protective atmosphere. The preheating zone temperature is 750°C, the high temperature zone temperature is 1120°C, and the sintering is carried out in the high temperature zone for 25-30 minutes before cooling. The mesh belt speed is 100mm / min. The tensile strength of the sintered state reaches 450-500Mpa, and the hardness can reach 75HRB.

[0038] S4: Carburizing heat treatment, carbon potential 0.6%, quenching temperature 850℃, quenching oil temperature 60℃, holding time 90 minutes, tempering temperature 180℃, tempering time 120 minutes; the ultimate tensile strength of the final material can reach 620-700Mpa, and the surface hardness HRC35-HRC45;

[0039] Pre-treatment step S5: polishing the sintered part with a vibrating polishing machine using stainless steel filigree abrasive for 20 minutes, and cleaning with an ultrasonic cleaning machine for 30 minutes at a frequency of 40-50 Hz using hydrocarbon as the medium;

[0040] S5: Processing the ø7 hole and two ø3 holes through the drilling process, and processing the inner wall of the hole through the finishing process to obtain the sintered part;

[0041] Product cost: Cast blanks have low precision, and internal hole and height dimensions rely entirely on post-processing, resulting in high processing costs. Using powder metallurgy, height tolerances can be guaranteed to within 0.2mm. Ø8 and Ø12 holes can be formed in one go, eliminating the need for secondary processing. Furthermore, product appearance is highly consistent, reducing processing costs by approximately 30%.

[0042] Example 2:

[0043] The difference between the second embodiment and the first embodiment is that step S3A is replaced by step S3B.

[0044] Step S3B: sintering is performed using a box-type furnace. The powder compact is tilted. The angle limiting rod 1 and the torsion support limiting rod 2 respectively support the corner ends of the tube in the powder compact. The powder compact is sintered in two steps.

[0045] See also Figure 5 The generator adjustment arm is centered on the ø12 hole, with rod bodies on both sides. The mass of the special-shaped end of the generator adjustment arm is much greater than the mass of the straight rod part.

[0046] pass Figure 2 It can be seen that the widths of the generator adjustment arm at both ends are 16.8mm and 17mm respectively, while the ø12 hole tube is 20mm long. Figure 1 The length of the shaped end reaches 43mm, and the length of the straight rod reaches 38mm. The shaped end is also heavier than the straight rod. Therefore, if the generator adjustment arm is placed horizontally and the end face of the ø12-hole tube contacts the contact surface, the shaped end will definitely tilt to one side and contact the contact surface.

[0047] It is known that the ø12 hole tube is cylindrical. The ø12 hole tube cannot contact the contact surface horizontally and tilts to one end. At this time, the contact area between the ø12 hole tube and the contact surface is a point. The unsintered ø12 hole tube has low strength and is easy to break and deform. If the chamfer of the ø12 hole tube is stamped once, the ø12 hole tube will be Figure 6 The tilt shown is still point contact. Point contact pressure increases, posing a risk of damage.

[0048] Box-type furnaces use high-temperature resistant pallets as carriers, with generator adjustment arms stacked horizontally in multiple layers. In addition to the aforementioned issues, there's also the problem of collection. During collection, the generator adjustment arms on each pallet must be collected individually, making it difficult to quickly collect them.

[0049] Therefore, the embodiment utilizes the mass distribution characteristics of the generator adjusting arm to design a new support structure, which solves the support and access problems of the generator adjusting arm and has a simple structure.

[0050] Before explaining the principle, the limiting oblique line 100 and the workpiece center line 200 are explained here.

[0051] pass Figure 4 It can be seen that the generator adjustment arm is a long strip structure, the workpiece center line 200 is located at the midpoint of the center axis of the ø12 hole tube, and the workpiece center line 200 is parallel to the straight rod plane of the ø generator adjustment arm.

[0052] In this embodiment, the angle limiting rod 1 and the torsion support limiting rod 2 are used to support the generator adjustment arm. Figure 4 The plane shown in the figure is the xOy plane, and the z direction is perpendicular to the xOy plane. Figure 4 They are displayed as points in the xOy plane.

[0053] The workpiece centerline 200 is rotated and tilted to the left in the xOy plane, and the limit inclined line 100 is rotated and tilted to the right in the xOy plane. The intersection of the limit inclined line 100 and the workpiece centerline 200 is located at the midpoint of the center axis of the ø12 hole tube.

[0054] pass Figure 2 It can be seen that the ø12 hole tube, the straight rod part, and the special-shaped end all have corners. Therefore, with the corner as the center, the balance of the generator adjustment arm is achieved by utilizing the mass difference between the special-shaped end and the straight rod part.

[0055] One end of the powder compact with a ø7 hole is located above the torsion support limit rod. Figure 1 As can be seen, the ø7 hole is located at the shaped end. The torsional support stopper 2 is located at the bottom of the corner between the ø12-hole tube and the shaped end. The shaped end is positioned below, and the gravity on the shaped end is greater than that on the straight portion. In this position, the generator adjustment arm tends to rotate rightward around the torsional support stopper 2. The angle limiter 1 is located at the top of the corner between the ø12-hole tube and the straight portion. Because the stopper's oblique line 100 and the workpiece centerline 200 are tilted in opposite directions, the angle limiter 1 precisely blocks the rotation of the straight portion, ensuring balanced positioning of the generator adjustment arm. After sintering, the generator adjustment arm shrinks in size. The weight of the shaped portion affects the arm, causing it to rotate around the torsional support stopper 2. The angle limiter 1 slides along the straight portion, maintaining a fixed position. Furthermore, as the generator adjustment arm shrinks, its strength increases. As the workpiece centerline 200 approaches vertical, the gravity on the ø12-hole tube gradually increases. Therefore, deformation of the ø12-hole tube is avoided. The wall thickness of the ø12 hole tube is 3mm. Compared with the width of the corner tip, the 3mm wall thickness greatly increases the ø12 hole tube's ability to resist deformation under stress.

[0056] The reason for setting the above method is that if a matching positioning structure is used, such as a hole is opened at the bottom of the tray to accommodate the generator adjustment arm, the bottom surface of the generator adjustment arm is always in contact with the contact surface, which results in poor air circulation.

[0057] This approach maximizes the area of ​​the generator adjusting arm exposed to the protective atmosphere. Before sintering, the angle limit rod 1 and the torsion support limit rod 2 can accurately position the generator adjusting arm. After sintering, when the generator adjusting arm is reduced in size, the angle limit rod 1 and the torsion support limit rod 2 can still maintain positioning.

[0058] The horizontal spacing between the angle limit rod 1 and the torsion support limit rod 2 is smaller than the narrowest width of the powder compact. The narrowest width of the powder compact is Figure 4 The width of the upper middle straight rod. Since the ø12 hole tube is longer than the width of the straight rod, when the horizontal distance between the angle limit rod 1 and the torsion support limit rod 2 is less than the width of the narrowest end of the powder compact, the motor adjustment arm cannot be vertical and cannot fall.

[0059] To improve the convenience of collection, please refer to Figure 5 , Figure 5 The figure shows the number of center rods 3 and a row of motor adjustment arms, with multiple rows of motor adjustment arms spaced equidistantly along center rod 3. The diameter of center rod 3 is smaller than the ø12-hole tube. After the ø12-hole tube shrinks and its tilt angle changes, the inner wall of the ø12-hole tube cannot contact center rod 3. After processing is completed, angle limit rod 1 and torsion support limit rod 2 are removed. The ø12-hole tube and center rod 3 are combined to form multiple rows of motor adjustment arms, allowing for cleaning, polishing, or other process flow.

[0060] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A powder metallurgy process for a generator adjusting arm, characterized by: include: S1: Fe-Cu-C powder metallurgy materials were mixed in a 500 kg double cone mixer for 30 minutes; S2: Use a 200T molding press with a mold structure of two upper and lower parts, a friction core rod, and a pressing force of 50KN to obtain powder pressed parts. The powder pressed parts are formed into ø8 holes and ø12 holes in one step, and the density of the powder pressed parts is 6.9-7.0g / m³; S3: Sintering process temperature is 1120℃, sintering for 25-30 minutes and then cooling; S4: carburizing heat treatment, carbon potential 0.6%, quenching temperature 850℃, quenching oil temperature 60℃, holding time 90 minutes, tempering temperature 180℃, tempering time 120 minutes; S5: Processing the ø7 hole and two ø3 holes through the drilling process, and processing the inner wall of the hole through the finishing process to obtain the sintered part; The method comprises the steps of: sintering in a box furnace, tilting the powder compact, supporting the corner ends of the tube in the powder compact with an angle limiting rod (1) and a torsion support limiting rod (2), and sintering the powder compact twice; In step S3B, the center line of the long side of the powder compact is the workpiece center line (200), the line connecting the centers of the angle limiting rod (1) and the torsion support limiting rod (2) is the limiting oblique line (100), and the inclination direction of the workpiece center line (200) with respect to the vertical line is opposite to the inclination direction of the limiting oblique line (100) with respect to the vertical line; In step S3B, the horizontal spacing between the angle limiting rod (1) and the torsion support limiting rod (2) is smaller than the narrowest end width of the powder compact.

2. The powder metallurgy process for a generator adjusting arm according to claim 1, characterized in that: One end of the powder pressed part with the ø7 hole is located above the torsion support limiting rod (2).

3. The powder metallurgy process for a generator adjusting arm according to claim 1, characterized in that: A center rod (3) is inserted into the ø12 hole of the powder compact, and a plurality of powder compacts are inserted into the center rod (3).

4. The powder metallurgy process for a generator adjusting arm according to claim 1, characterized in that: The pretreatment step of step S5 is also included: a vibration polishing machine uses stainless steel filigree abrasive to polish the sintered part for 20 minutes, and an ultrasonic cleaning machine is used for cleaning for 30 minutes at a frequency of 40-50 Hz and the medium is hydrocarbon.

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