DESIGNING AND MANUFACTURING METHOD FOR POWDER INJECTION MOLDING PISTON RING

Abstract

A designing and manufacturing method for powder injection molding a piston ring comprises the following steps: (a) designing an elliptical equation of the piston ring according to the technical requirements of the piston ring product and providing the free opening gap size; (b) conducting engineering analysis on structural strength, stress-strain, and friction and wear by means of a computer; (c) designing and selecting a powder material, designing a proportion ratio of powder and adhesive, and manufacturing a feeding material for injection by means of mixing and granulating; (d) designing and manufacturing an injection mold for the elliptical piston ring; (e) manufacturing a three-dimensional elliptical piston ring blank by injecting, degreasing, sintering and post-processing; (f) cutting an opening; and (g) inspecting translucency, elasticity and size of the product, then packaging and delivering or warehousing. The present designing and manufacturing method employs the technique of powder injection molding and computer-aided design and engineering analysis, designs and selects powder materials, and designs a proportion ratio of powder and adhesive; due to feeding particles being uniform, the piston ring structure is more uniform, and has improvements over the traditional casting process with more design freedom.

Claims

1. A designing and manufacturing method for powder injection molding piston rings, which comprises the following steps: (1) Designing an elliptical equation of the piston rings according to the technical requirements of the piston ring product and providing the free opening gap size; (2) Conducting engineering analysis on structural strength, stress-strain, and friction and wear by means of a computer; (3) Designing and selecting a powder material, designing a proportion ratio of powder and adhesive, and manufacturing a feeding material for injection by means of mixing and granulating; (4) Designing and manufacturing an injection mold for the elliptical piston ring; (5) Manufacturing a three-dimensional elliptical piston ring blank by injecting, degreasing, sintering and post-processing; (6) Machining: cutting an opening, grinding the outer surface by Circle Method and double-side grinding both ends of the elliptical piston ring; then determining whether heat treatment is required to make cutting process convenient or meet the demand of surface hardness according to the mechanical properties of materials; (7) Inspecting translucency elasticity and size of the product, then packaging and delivering or warehousing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is the form of an oval piston ring in operation,

[0037] FIG. 2 is the form of an oval piston ring in free state,

[0038] FIG. 3 is a flow chart of piston ring produced by powder injection molding.

[0039] In the figure, 1, inner hole 2, outer surface 3, hatch 4, inner surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In order to make the technical proposal of the present invention better understood by the technicians in the field. The present invention will be described below in greater detail based on an example, with reference to the appended drawings.

[0041] A designing and manufacturing method for powder injection molding piston rings, which comprises the following steps:

[0042] (1) Product design: designing a three-dimensional elliptical equation and free opening gap size (such as 3, 3.5, 4, 4.5, 5 mm) of the three-dimensional elliptical piston rings according to the technical requirements of the piston ring product as well as injection mold;

[0043] (2) Computer aided engineer analysis: conducting engineering analysis on structural strength, stress-strain, and friction and wear by means of a computer;

[0044] (3) Select or design the material: selecting Fe base powder (such as sintered carbon steel F0112J, GB/T14667.1-93, with carbon content 0.4%0.7%, others less than 1.5%, and Fe for the rest) as material of 3D elliptical piston ring, and particle size is 1050 m; the material could also be Ni-base powder (such as IN100) or stainless steel-base powder (such as 1Cr13, 2Cr13 and 316L).

[0045] (4) Manufacture of feeding material: determining the weight ratio of Fe-base powder and binder (consisting of paraffin, HDPE, polypropylene and so on) according to elliptical piston ring material, and then manufacturing feeding material through mixing and prilling; the above weight ratio is 80 wt %85 wt % Fe-base powder and 15 wt %20 wt % binder.

[0046] (5) Regular powder injection molding process: manufacturing a three-dimensional elliptical piston ring blank by injecting, degreasing, sintering and post-processing.

[0047] (6) Machining: cutting an opening, grinding the outer surface by Circle Method and double-side grinding both ends of the elliptical piston ring.

[0048] (7) Inspecting translucency, elasticity and size of the product such as free opening gap size, then packaging and delivering or warehousing.

[0049] The mentioned mixing, injecting, degreasing and sintering refer to followings respectively:

[0050] a) Mixing: blending 80 wt %85 wt % Fe-base powder and 15 wt %20 wt % bonder made of paraffin, HDPE, polypropylene and stearic acid in a mixer at temperature of 150200 C. and speed of 3045 rpm for 3060 min to manufacture feeding material.

[0051] b) Injecting: forming the feeding material in a mold pressing machine for plastic at the temperature of 150200 C. and pressure of 20200 MPa, and then getting the blank of elliptical piston ring.

[0052] c) Degreasing: dipping the blank in organic solvent at temperature of 4060 C. for 24 h; And after drying, thermal degreasing at 200600 C. for 68 h with protection of decomposed ammonia.

[0053] d) Sintering: putting the degreased blank into vacuum sintering furnace at temperature of 13001850 C. for 2060 min, and then getting piston rings that meet the demand of shape and dimensional precision.

[0054] FIG. 1 shows a piston ring under the operating state. The outer surface of the mentioned piston is a circle and the inside surface is elliptical. FIG. 2 shows a piston ring under free state. Both the outer and inside surface is elliptical and the opening gap size is larger than that under operating state. FIG. 3 shows the flow chart of piston ring produced by powder injection molding in present invention.

[0055] Although some examples of methods have been illustrated in the accompanying Drawings and described in the foregoing DESCRIPTION OF THE PREFERRED EMBODIMENTS, it will be understood that the example embodiments disclosed are not limiting, but are capable of numerous rearrangements, modifications and substitutions.