Cavitation Surface Treatment Method

Abstract

Increase the surface grinding speed by cavitation processing method. [Solution] The cavitation surface treatment method involves mixing an abrasive 7 into a treatment liquid 5, immersing a workpiece 3 and a horizontal projection nozzle 12 in the treatment liquid 5, and while rotating around a jet axis 1, spraying a cavitation jet 32 ​​spreading on a plane toward the surface of the workpiece 3, smoothing the surface of the workpiece 3 and imparting compressive residual stress to the surface of the workpiece 3.

Description

[Technical field]

[0001] The present invention relates to a cavitation surface treatment method. [Background technology]

[0002] A cavitation surface treatment method called cavitation abrasive surface finishing (CASF) is known, in which a cavitation jet is used to smooth the roughness of a workpiece surface and perform peening (US2024 / 0001509A1). Summary of the Invention [Problem to be solved by the invention]

[0003] According to conventional cavitation treatment methods, the surface grinding speed may be slow. An object of the present invention is to increase the surface grinding speed by the cavitation treatment method. [Means for solving the problem]

[0004] The first aspect of the present invention is The abrasive is mixed into the processing liquid, The workpiece and the horizontal projection nozzle are immersed in the treatment liquid, The flat nozzle rotates around the jet axis and jets a cavitation jet spreading on a plane toward the surface of the workpiece, smoothing the surface of the workpiece and imparting compressive residual stress to the surface of the workpiece; A cavitation surface treatment method.

[0005] A second aspect of the present invention is The cavitation jet, which has a cavity that spreads like a ribbon in a spiral shape, collides with the surface to be treated, which is the surface of the workpiece, while taking in the abrasive. The cavity collapses near the surface to be treated, and the cavity cloud with the abrasive flows along the surface to be treated, abrading the surface to be treated and imparting a residual compressive stress to the surface to be treated. A cavitation surface treatment method. Effect of the Invention

[0006] According to the cavitation treatment method of the present invention, the surface grinding rate is increased. [Brief description of the drawings]

[0007] [Figure 1] Schematic diagram of a cavitation treatment device according to embodiment 1. [Diagram 2] FIG. 1 is a longitudinal sectional view of a nozzle according to a first embodiment. [Diagram 3] View of arrow III in Figure 2 [Figure 4] Sequential photographs of the cavitating jet of embodiment 1 [Diagram 5] Schematic diagram of a cavitation treatment device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Embodiment 1> As shown in Fig. 1, a cavitation treatment device 10 of this embodiment includes a treatment tank 11, a nozzle 12, a pump 23, and a moving device 21. The treatment tank 11 has an opening at the top. The treatment tank 11 stores a treatment liquid 5 and an abrasive 7. The abrasive 7 is suspended in the treatment liquid 5.

[0009] The nozzle 12 is disposed on a moving device 21. The moving device 21 freely moves the nozzle 12 in the left-right direction (X), the front-back direction (Y), and the up-down direction (Z). The nozzle 12 is connected to a pump 23. The nozzle 12 is a horizontal nozzle.

[0010] Fig. 2 is a cross-sectional view of the nozzle 12 taken along the ZX plane passing through the injection axis 1. As shown in Fig. 2 and Fig. 3, the nozzle 12 has a nozzle head 13 and a nozzle tip 17. The nozzle head 13 is in the shape of a round pipe.

[0011] The nozzle head 13 has, in order from the base end (upper part in FIG. 2), a flow path 13a, a nozzle chamber 13b, and a jet flow passage port 13c. The flow path 13a is a cylindrical hole. The nozzle chamber 13b is a right cylinder. The nozzle chamber 13b is connected to the flow path 13a. For example, the nozzle chamber 13b has a smaller diameter than the flow path 13a. The jet flow passage port 13c is disposed at the tip of the nozzle head 13 and is connected to the nozzle chamber 13b. The jet flow passage port 13c is a cylindrical hole. The jet flow passage port 13c has a smaller diameter than the nozzle chamber 13b.

[0012] The nozzle tip 17 is cylindrical and disposed in the nozzle chamber 13b. Preferably, the nozzle tip 17 abuts against the nozzle chamber 13b. The nozzle tip 17 is made of, for example, a gem, an artificial gem, or a sintered body of an artificial gem. The nozzle tip 17 has, in order from the base end, an inlet 17a, a throttle 17b, and a discharge groove 17c. The inlet 17a and the throttle 17b are disposed around the injection axis 1. The inlet 17a is a right circular cone, and the diameter becomes smaller toward the tip. The throttle 17b is a right elliptical cylinder. As shown in FIG. 3, the major axis of the throttle 17b extends in the X direction. The throttle 17b is directly connected to the inlet 17a. The throttle 17b opens into the discharge groove 17c. As shown in FIG. 3, the discharge groove 17c is disposed on the tip surface of the nozzle tip 17 and extends in the X direction. As shown in FIG. 2, the YZ cross section of ejection groove 17c is semicircular.

[0013] As shown in FIG. 1, the collision area 34 between the cavitation jet 32 ​​and the workpiece 3 is, for example, an elongated ellipse. Spout angle 37 is 5 to 10 degrees.

[0014] The workpiece 3 has a surface 3a to be treated. The surface 3a to be treated is a flat surface. The workpiece 3 is, for example, additively manufactured by the powder bed method. The surface 3a to be treated is given a tensile residual stress. The surface 3a to be treated has unmelted powder (α case). The surface 3a to be treated is the surface of the workpiece 3. The surface 3a to be treated is a target portion from which the unmelted powder is removed and to which a compressive residual stress is given.

[0015] The cavitation treatment method of this embodiment will be described with reference to FIG. 1. First, a workpiece 3 is placed on the bottom of a treatment tank 11. The workpiece 3 is immersed in a treatment liquid 5. A surface 3a to be treated extends in the XY plane. The nozzle 12 is positioned by a moving device 21 at a position away from the surface 3a to be treated by an offset distance 35. The nozzle 12 is immersed in the treatment liquid 5. The injection axis 1 extends in the Z direction. The moving device 21 rotates the nozzle 12 at a rotational speed 31. Preferably, the rotational speed 31 is 100 to 200 revolutions per minute.

[0016] The pump 23 then pressurizes the processing liquid 5 and sends it to the nozzle 12. The processing liquid 5 passes through the flow path 13a, the inlet 17a, and the opening of the throttle 17b, and is jetted out as a cavitation jet 32. At this time, the processing liquid 5 is accelerated at the inlet 17a, and when it is discharged from the throttle 17b, the cavitation jet 32 ​​spreads out in a plate shape. Then, a vortex is generated due to a speed difference near the interface between the processing liquid 5 stored in the processing tank 11 and the cavitation jet 32, and a pressure difference occurs, promoting the generation of cavities. The cavitation jet 32 ​​contains many cavities. The cavitation jet 32 ​​passes through the jet passage port 13c and collides with the workpiece 3. The moving device 21 may move the nozzle 12 along a predetermined moving path 33 at a constant speed while maintaining the offset distance 35.

[0017] Figure 4 shows a series of photographs taken by a high-speed camera of the state of the cavitating jet 32. The photographs were taken continuously every 0.024 seconds with no abrasive in the tank. The results are shown in the order of photographs 411 to 415. The cavities contained in the cavitating jet 32 ​​look like white clouds. As shown in Fig. 4, the cavitation jet 32 ​​moves toward the workpiece 3 like a thin ribbon twisted in a spiral shape. Then, the cavity collapses in the vicinity of the workpiece 3. The abrasive 7 is caught up in the cavitation jet 32. The abrasive 7 is subjected to the fluid drag of the cavitation jet 32 ​​and flows along the cavitation jet 32. The abrasive 7 collides with the workpiece 3 and flows radially around the jet axis 1 along the workpiece 3.

[0018] According to the cavitation treatment of this embodiment, the abrasive 7 is caught in the cavitation jet 32, so that the amount of the abrasive 7 colliding with the workpiece 3 increases. Also, the amount of the abrasive 7 flowing on the surface of the workpiece 3 increases. This increases the amount of the workpiece 3 that is ground. EXAMPLES

[0019] Cavitation treatment was carried out under the following conditions. The amount of grinding is the depth from the unmachined workpiece surface to the machined surface. The surface roughness was measured with a stylus surface roughness measuring device. The surface residual stress of the workpiece was measured by X-ray stress measurement (cos α method). The X-ray stress measuring device used was a Pulstec Industrial μ-X360s portable X-ray residual stress measuring device. When the rotation speed was 0 degrees, the direction in which the cavitation jet 32 ​​spread was the X direction, and the movement path 33 was the Y direction. Workpiece: Ti alloy additive manufacturing using powder bed method Treatment liquid: Water Abrasive: Alumina powder (grain size: 60μm~70μm) Cavitation jet 32 ​​flow rate: 6.5L / min · Spout angle 37:10 degrees Offset distance 35: 150mm ·Moving speed: 50mm / s Rotation speed: 0~300(1 / min)

[0020] The resulting grinding amount is shown in Table 1. The grinding amount was significantly increased by rotating at a speed of 100 to 200 revolutions per minute. The surface residual stress after processing was -609 MPa. [Table 1]

[0021] <Embodiment 2> As shown in FIG. 5, in this embodiment, cavitation treatment is performed on a workpiece 103. The workpiece 103 has a cavity 103b. The cavity 103b has an axis 103c and a wall surface (surface to be treated) 103a. Preferably, the axis 103c is in the Z direction. The cavity 103b is, for example, a through hole. The axis 103c is aligned with the injection axis 1. The moving device 21 rotates the nozzle 12 at 100 to 200 revolutions per minute. The moving device 21 may feed the nozzle 12 in the axial direction.

[0022] The cavitation jet 32 ​​turns into a thin spiral ribbon, entraining the abrasive 7 and entering the cavity 103b. The cavitation jet 32 ​​collides with the wall surface 103a together with the abrasive 7. The abrasive 7 and the cavity cloud then flow along the wall surface 103a. The cavity collapses near the wall surface 103a, imparting compressive residual stress to the surface of the wall surface 103a.

[0023] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention, and all technical matters included in the technical ideas described in the claims are the subject of the present invention. The above-described embodiment shows a preferred example, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the attached claims. [Explanation of symbols]

[0024] 1 Injection axis 3 Work 3a Surface to be treated 5 Processing solution 7 Abrasive material 10. Cavitation treatment device 12 Flat nozzle 32 Cavitation jet

Claims

1. The abrasive is mixed into the processing liquid, The workpiece and the flat projection nozzle are immersed in the treatment liquid, The flat nozzle having a spray angle of 5° to 10° around the spray axis rotates around the spray axis at 100 to 200 revolutions per minute and sprays a cavitation jet spreading on a plane toward the surface of the workpiece, smoothing the surface of the workpiece and imparting compressive residual stress to the surface of the workpiece; Cavitation surface treatment method.

2. The workpiece has a surface to be processed, The injection axis extends in a direction perpendicular to the surface to be treated. The cavitation surface treatment method according to claim 1 .

3. The workpiece has a hole to be processed, The injection axis extends in the direction in which the treatment target hole extends. The cavitation surface treatment method according to claim 1 .

4. The treatment liquid flows through the liquid inlet, is rectified and accelerated, passes through the throttle port, and is ejected in a flat plate shape so as to spread along the discharge groove. The cavitation surface treatment method according to any one of claims 1 to 3.

5. A cavitation jet with a cavity spreading out like a ribbon that draws a spiral is ejected from a flat nozzle that rotates at 100 to 200 revolutions per minute around the ejection axis and has an ejection angle of 5° to 10° around the ejection axis, The cavitation jet impinges on the surface to be treated, which is the surface of the workpiece, while taking in the abrasive. The cavity collapses near the surface to be treated, and the cavity cloud with the abrasive flows along the surface to be treated, abrading the surface to be treated and imparting a residual compressive stress to the surface to be treated. Cavitation surface treatment method.

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