Powder metallurgy one-way clutch outer ring and manufacturing process thereof

Abstract

The powder metallurgy one-way clutch outer ring comprises an outer ring body, a cavity used for concentrically arranging an inner ring is formed in the inner side of the outer ring body, and a plurality of limiting grooves are evenly formed in the inner wall of the outer ring body in the circumferential direction; a first limiting part used for installing an elastic piece and a second limiting part used for installing a ball are arranged in the limiting groove, the working face of the ball limiting part is a curved surface, the curved surface is of an eccentric arc structure or a cycloid arc structure or an Archimedes spiral structure, and the distance between the curved surface and the inner ring is gradually reduced in the clockwise direction. The elastic pieces drive the balls to be attached to the curved surfaces and the outer wall face of the inner ring in the natural state. According to the powder metallurgy one-way clutch outer ring and the manufacturing process thereof, the die wall lubricating or warm die pressing forming process is combined with the surface densification process, the torsional strength and the surface contact strength of the outer ring are improved, meanwhile, the abrasion resistance of a working part is improved, the service life is prolonged, and therefore the actual use requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of overrunning clutches, and particularly to an outer ring of a powder metallurgy overrunning clutch and its manufacturing process. Background Art

[0002] The overrunning clutch is a key component in the automotive power system. Its function is to transmit power unidirectionally. During forward transmission, through the locking function of the internal structure, the outer ring and the inner ring are locked and relatively fixed to transmit normal torque. When rotating in the reverse direction, the outer ring and the inner ring will disengage and rotate normally without affecting each other, minimizing the impact on the operation process when the automotive transmission or other power transmission devices change the power transmission.

[0003] The earliest one to achieve this function was the ratchet overrunning clutch, but its noise and impact are relatively large, and it is not suitable for use in occasions with high-speed and high-life requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to overcome the deficiencies of large noise, large impact, and low service life of the overrunning clutch in the prior art, the present invention provides an outer ring of a powder metallurgy overrunning clutch and its manufacturing process.

[0005] The technical solution adopted by the present invention to solve its technical problems is: an outer ring of a powder metallurgy overrunning clutch and its manufacturing process, including an outer ring body. A gear ring is provided on the outer side of the outer ring body. A cavity for concentrically arranging an inner ring is provided on the inner side of the outer ring body. A plurality of limiting grooves are uniformly arranged along the circumferential direction on the inner wall of the outer ring body. A first limiting portion for installing a leaf spring and a second limiting portion for installing a ball are provided in the limiting grooves. The working surface of the ball limiting portion is a curved surface, and the curved surface is an eccentric circular arc structure, a cycloid circular arc structure, or an Archimedean spiral structure. The distance between the curved surface and the inner ring gradually decreases in the clockwise direction. In the natural state, the leaf spring drives the balls to be respectively in contact with the curved surface and the outer wall surface of the inner ring.

[0006] The curved surface and the inner ring cooperate to form a gradually decreasing space. According to the relative motion relationship, when the outer ring is stationary and the inner ring rotates clockwise, it will drive the balls to rotate towards the place with a smaller space and get stuck, relatively fixing the inner and outer rings to transmit torque. When the inner ring rotates counterclockwise, the balls rotate towards the place with a larger space, and the inner and outer rings disengage and do not transmit torque. Among them, in the natural state, the leaf spring drives the balls to be respectively in contact with the curved surface and the outer wall surface of the inner ring. In this way, once the inner ring rotates clockwise, the inner and outer rings can be quickly locked, maximizing the reaction efficiency.

[0007] The present invention provides a manufacturing process for an outer ring of a powder metallurgy overrunning clutch, including the following steps:

[0008] (1) Ingredient preparation: Put Mo: 0.5 - 1.0 wt%, Mn: 0.05 - 0.3 wt%, Ni: 0 - 2 wt%, Cu: 0 - 0.4 wt%, with the rest being Fe, into a mixer according to the ratio for powder mixing.

[0009] (2) Forming: Take the powdered material after ingredient preparation and put it into a press. Adopt the die wall lubrication or warm die pressing forming process, and use a pressure of 80T - 300T to press the powdered material into the shape of the outer ring body, so that the density of the outer ring body after one - time pressing reaches 7.2 - 7.6 g / cm3.

[0010] Adopt the die wall lubrication or warm die scheme. Die wall lubrication is to spray the lubricant onto the inner wall of the die to reduce the friction between the metal powder and the die, thereby improving the pressing density of the part; warm die pressing is to set corresponding oil - temperature heating pipelines on the die to heat the die, and use the warm - pressing lubricant in the formula raw materials to improve the pressing density of the part.

[0011] (3) Sintering: Place the outer ring body in a sintering furnace. In a protective atmosphere of nitrogen, first degrease at 750 - 800 °C; then raise the temperature to 1100 - 1150 °C, and keep sintering for 20 - 30 minutes after the temperature is stable; cool to room temperature.

[0012] (4) Densification and sizing: Use an upper punch die, a lower punch die, a middle die and a core rod to form a sizing die. By making the sizing allowances of the core rod die and the external middle die different, increase the sizing allowance of the middle hole part by 0.5 mm, thereby increasing the density of the inner hole part locally to meet the requirement of up to 7.7 g / cm3.

[0013] (5) Heat treatment: The outer ring body adopts carburizing heat treatment, and the martensite structure on the surface after heat treatment increases zero wear resistance.

[0014] (6) Machining: Carry out chamfering treatment, deburring treatment and surface grinding on the outer ring body.

[0015] Furthermore, the elastic piece is made of stainless steel. The elastic piece is usually produced with similar grades such as SUS301, and has advantages such as high elastic life.

[0016] Furthermore, the ball is made of wear - resistant steel. The ball is usually made of GCr15 or materials with equivalent grades, has high hardness and good wear resistance, and the surface roughness reaches Ra0.8 or more through grinding.

[0017] The beneficial effects of the present invention are as follows: A powder - metallurgy one - way clutch outer ring and its manufacturing process provided by the present invention adopt the die wall lubrication or warm die pressing forming process and combine with the surface densification process, which improves the torsional strength and surface contact strength of the outer ring, and at the same time improves the wear resistance of the working part, extends the service life, so as to meet the actual use requirements. Brief Description of the Drawings

[0018] The present invention will be further described below in conjunction with the drawings and embodiments.

[0019] Figure 1 is a schematic structural diagram of the best embodiment of the present invention;

[0020] Figure 2 is a schematic structural diagram of a one-way clutch;

[0021] Figure 3 is a schematic structural diagram of a densification shaping die.

[0022] In the figure: 1. Outer ring body, 11. First limiting part, 12. Second limiting part, 121. Curved surface, 2. Elastic piece, 3. Ball, 4. Inner ring, 5. Upper punch die, 6. Lower punch die, 7. Middle die, 8. Core rod. Detailed Embodiment

[0023] The present invention will now be described in detail with reference to the drawings. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, so it only shows the components related to the present invention.

[0024] As Figures 1-3 shown, an outer ring of a powder metallurgy one-way clutch of the present invention includes an outer ring body 1. A gear ring is provided on the outer side of the outer ring body 1. A cavity for concentrically arranging an inner ring 4 is provided on the inner side of the outer ring body 1. A plurality of limiting grooves are uniformly arranged along the circumferential direction on the inner wall of the outer ring body 1. A first limiting part 11 for installing an elastic piece 2 and a second limiting part 12 for installing a ball 3 are provided in the limiting grooves. The working surface of the limiting part of the ball 3 is a curved surface 121. The curved surface 121 is an eccentric arc structure, a cycloid arc structure or an Archimedean spiral structure. The distance between the curved surface 121 and the inner ring 4 gradually decreases in the clockwise direction. In the natural state, the elastic piece 2 drives the balls 3 to be respectively in contact with the curved surface 121 and the outer wall surface of the inner ring 4.

[0025] A manufacturing process for an outer ring of a powder metallurgy one-way clutch provided by the present invention includes the following steps:

[0026] (1) Ingredient preparation: Put Mo: 0.85wt%, Mn: 0.05 - 0.3wt%, C: 0.2wt%, and the rest is Fe into a mixer according to the ratio for powder mixing;

[0027] (2) Forming: Take the powdered material after ingredient preparation and put it into a press. Adopt a die wall lubrication or warm die pressing forming process, and press the powdered material into the shape of the outer ring body 1 with a pressure of 80T - 300T, so that the density of the outer ring body 1 reaches 7.2 - 7.6 g / cm3 in one pressing;

[0028] (3) Sintering: Place the outer ring body 1 in a sintering furnace. In a protective atmosphere of nitrogen, first degrease it at 750 - 800 °C; then raise the temperature to 1100 - 1150 °C, and keep sintering for 20 - 30 minutes after the temperature stabilizes; cool to room temperature.

[0029] (4) Densification and sizing: Use an upper punch die 5, a lower punch die 6, a middle die 7, and a mandrel 8 to form a sizing die. By making the sizing allowances of the mandrel die and the external middle die different, increase the sizing allowance of the middle hole part by 0.5 mm, thereby increasing the density of the inner hole part locally to meet the requirement of up to 7.7 g / cm3.

[0030] (5) Heat treatment: The outer ring body 1 is subjected to carburizing heat treatment, and the martensite structure on the surface after heat treatment increases zero wear resistance.

[0031] (6) Machining: Chamfer and deburr the outer ring body 1, and perform surface grinding.

[0032] The elastic piece 2 is made of stainless steel.

[0033] The ball 3 is made of wear-resistant steel.

[0034] In the present invention, directions and references (e.g., up, down, left, right, etc.) can only be used to assist in the description of the features in the drawings. Therefore, the following specific embodiments are not adopted in a restrictive sense, and the scope of the claimed subject matter is defined only by the appended claims and their equivalents.

[0035] Based on the above inspiration from the ideal embodiments of the present invention, through the above description, relevant workers can make various changes and modifications without departing from the scope of the present invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A powder metallurgy one-way clutch outer ring, characterized in that: The invention comprises an outer ring body (1), the outer side of the outer ring body (1) is provided with a gear ring, the inner side of the outer ring body (1) is provided with a cavity for concentrically arranging an inner ring (4), a plurality of limit grooves are evenly arranged on the inner wall of the outer ring body (1) along the circumferential direction, a first limit portion (11) for mounting a spring sheet (2) and a second limit portion (12) for mounting a ball (3) are arranged in the limit groove, the working surface of the limit portion of the ball (3) is a curved surface (121), the curved surface (121) is an eccentric arc structure, a cycloid arc structure or an Archimedean spiral structure, the spacing between the curved surface (121) and the inner ring (4) gradually decreases in the clockwise direction, and the spring sheet (2) drives the ball (3) to fit the curved surface (121) and the outer wall of the inner ring (4) respectively in a natural state.

2. The manufacturing process of a powder metallurgy one-way clutch outer ring according to claim 1, characterized in that: The following steps are involved: (1) Mixing: Mo: 0.5-1.0wt%, Mn: 0.05-0.3wt%, Ni: 0-2wt%, C: 0-0.4wt%, and the rest is Fe, which are put into a mixer according to the mixing ratio for powder mixing; (2) Forming: Put the formulated powder into a press, and use a die wall lubrication or warm die pressing process to press the powder into the shape of the outer ring body (1) at a pressure of 80T-300T, so that the density of the outer ring body (1) reaches 7.2-7.6g / cm3 at one time; (3) Sintering: Place the outer ring body (1) in a sintering furnace, degrease at 750-800°C in a nitrogen atmosphere, then raise the temperature to 1100-1150°C, and keep sintering for 20-30 minutes after the temperature stabilizes; then cool to room temperature; (4) Densification shaping: The shaping die is composed of an upper punch (5), a lower punch (6), a middle die (7) and a core rod (8). The shaping margins of the middle hole are increased by 0.5 mm in depth due to the different shaping margins of the core rod die and the external middle die, thereby increasing the density of the inner hole to a maximum of 7.7 g / cm3. (5) Heat treatment: The outer ring body (1) is subjected to carburizing heat treatment, and the martensitic structure on the surface after heat treatment increases zero wear resistance; (6) Machining: The outer ring body (1) is chamfered and deburred, and surface ground.

3. A process for manufacturing a powder metallurgy one-way clutch outer ring as claimed in claim 2, characterized in that: The spring piece (2) is made of stainless steel.

4. A process for manufacturing a powder metallurgy one-way clutch outer ring as claimed in claim 2, characterized in that: The balls (3) are made of wear-resistant steel.

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