Polishing method for inner wall of hollow metal part

Abstract

A polishing method for an inner wall of a hollow metal part, including: firstly, placing a coaxial cathode in an inner hole of a metal part when a metal part model is designed, and printing the metal part model and the coaxial cathode together; then, sealing two ends of an inner hole cavity of the metal part by using a light curing part, fixing the coaxial cathode, filling the cavity with a polishing solution, and performing polishing treatment by using an electrochemical polishing method; and finally, reversing an electrode to break the coaxial cathode and take out the broken coaxial cathode to obtain a polished metal part. The polishing of a complex-shaped inner hole of a 3D-printed metal part is realized, the defect that an inner hole of a 3D-printed metal part with a complex-shaped hollow part cannot be polished by using a traditional machining method is overcome, the problem that an inner wall of a metal part polished by using an electrochemical method is non-uniform is solved, the surface quality of the inner hole of the 3D-printed metal part with the complex-shaped hollow part is improved, and the application prospect and postprocessing technology of the 3D-printed metal part are expanded.

Claims

1. A polishing method for an inner wall of a hollow metal part, wherein comprising three steps in total: designing and printing, sealing and polishing as well as reversing and breaking: (1) designing and printing: adding a coaxial cathode model in an inner hole of a metal part model when designing the metal part model, the coaxial cathode model is corresponding to the inner hole in shape and size and provided with 1-3 breakable structures in the middle part thereof, wherein the breakable structures form breaking points; and printing a metal part and a coaxial cathode together by using a 3D printer to complete the designing of the metal part model and the coaxial cathode model and the printing of the metal part and the coaxial cathode; (2) sealing and polishing: sealing two ends of the inner hole of the metal part by using a light curing sealing ring adapted to the inner hole of the metal part in shape, fixing the coaxial cathode, introducing a polishing solution into the sealed inner hole serving as an electrochemical polishing tank, taking the coaxial cathode as a cathode and the metal part as an anode, and performing electrochemical polishing on an inner surface of the metal part; and (3) reversing and breaking: reversing the electrodes, taking the coaxial cathode as the anode and the metal part as the cathode, fusing the breakable structures of the coaxial cathode to break the coaxial cathode, removing the light curing sealing ring, discharging the polishing solution, and taking the broken coaxial cathode out of the inner hole of the metal part to complete reversing and breaking, and realizing the polishing of the inner surface of the metal part.

2. The polishing method for the inner wall of the hollow metal part according to claim 1, wherein the coaxial cathode is made of an iron-based material, a nickel-based material or a titanium-based material; the size of the coaxial cathode is selected according to the size of the inner hole of the metal part; the breakable structures are reticular supporting structures; the light curing sealing ring is made of light curing resin, and the size of the light curing sealing ring is selected according to the size of the inner hole of the metal part; and the polishing solution is selected according to a metal material required to be polished.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a block diagram of a technical process of the present disclosure;

(2) FIG. 2 is a schematic diagram of a principle in step (1) involved in the present disclosure;

(3) FIG. 3 is a schematic diagram of a principle in step (2) involved in the present disclosure;

(4) FIG. 4 is a schematic diagram of a fusing principle in step (3) involved in the present disclosure; and

(5) FIG. 5 is a schematic diagram of a breaking principle in step (3) involved in the present disclosure.

DETAILED DESCRIPTION

(6) The present disclosure is further described below with embodiments in combination with the accompanying drawings.

Embodiment 1

(7) A technical process of a polishing method for an inner wall of a hollow metal part provided by the present disclosure includes three steps in total: designing and printing, sealing and polishing as well as reversing and breaking: (1) designing and printing: when a metal part model is designed, a coaxial cathode model corresponding to an inner hole 1 of a metal part model in shape and size is added in the inner hole 1, 1-3 breaking points 3 with reticular structures are arranged in the middle of a coaxial cathode 2, and the metal part and the coaxial cathode 2 are printed together by using a 3D printer to complete the designing of the metal part model and the coaxial cathode model and the printing of the metal part and the coaxial cathode 2; (2) sealing and polishing: the metal part and the coaxial cathode 2 are cut off together, powder inside the metal part is cleared, two ends of the inner hole 1 of the metal part are sealed by a light curing sealing ring 4 adapted to the inner hole of the metal part in shape, the coaxial cathode 2 is fixed, a polishing solution 5 is introduced into the sealed inner hole serving as an electrochemical polishing tank, the coaxial cathode 2 is connected to a cathode of a power source, the surface of the inner hole 1 of the metal part is connected to an anode of the power source, and electrochemical polishing is performed on the surface of the inner hole 1 of the metal part by virtue of a hollow structure of the metal part; and (3) reversing and breaking: the electrodes is reversed, the coaxial cathode 2 is connected to the anode of the power source, the surface of the inner hole 1 of the metal part is connected to the cathode of the power source, the breaking points 3 of the coaxial cathode 2 are fused, the light curing sealing ring 4 is removed, the polishing solution 5 is discharged, and the coaxial cathode 2 broken by corrosion is taken out of the inner hole 1 of the metal part to complete reversing and breaking and realize the polishing of the surface of the inner hole 1 of the metal part.

(8) The parts and the coaxial cathode involved in the present disclosure may be each made of a traditional metal additive manufacturing material such as an iron-based material, a nickel-based material and a titanium-based material; the size of the coaxial cathode may be selected according to the size of the inner hole of the part; the breakable structures are reticular supporting structures; the light curing sealing ring is generally made of light curing resin, and the size of the light curing sealing ring is selected according to the size of the inner hole of the metal part; and the polishing solution may be selected according to a metal material required to be polished.

(9) Although several embodiments of the present disclosure have been given herein, the skilled in the art should understand that the embodiments described herein can be changed without departing from the spirit of the present disclosure. The above-mentioned embodiments are merely exemplary, but should not be used as a limitation to the scope of the present disclosure.