Patent Application
20250041993
This application claims the benefit of priority to Japanese Patent Application No. 2023-127750, filed on Aug. 4, 2023, the entire contents of which are hereby incorporated by reference.
The present invention relates to a cavitation processing method and a cavitation processing apparatus for performing a cavitation processing on a surface of a workpiece.
Conventionally, a cavitation processing is performed on a workpiece made of metal (Japanese Patent No. 6872929). In the cavitation processing, a jet of a fluid containing a cavity (bubble) is caused to collide with the workpiece to process the surface of the workpiece by an impact force when the cavity collapses. The cavitation processing applies compressive residual stress to the surface of the workpiece.
The workpiece on which the cavitation processing is performed has various shape and size. In order to perform an appropriate cavitation processing, it is necessary to cause the jet to collide with the surface of the workpiece by an appropriate method according to the conditions of the workpiece.
An object of the present invention is to provide a cavitation processing method and a cavitation processing apparatus that perform the cavitation processing on a bottom portion of a groove of the workpiece.
A first aspect of the present invention provides a cavitation processing method, including:
A second aspect of the present invention provides a cavitation processing apparatus, including:
In the cavitation processing, the workpiece, the nozzle, and the guide member are immersed in the processing liquid stored in the tank. In the processing liquid, a jet of the processing liquid is ejected from the nozzle toward the guide member. The processing liquid is, for example, water. The processing liquid may be a mixture of water and an abrasive. The abrasive material may be clouded with the processing liquid stored in the tank.
The workpiece is made of metal. The metal constituting the workpiece is, for example, a heat-resistant alloy, an aluminum alloy, a magnesium alloy, titanium, a titanium alloy, or steel. The workpiece is, for example, a mechanical part, a medical device part, or a medical device. Mechanical part is, for example, a gear, a pipe, a valve, a pipe fitting, or an aerospace part. The medical device may be a surgical implant. The aerospace part may be an aircraft engine component or other aircraft component, a rocket engine component, a spacecraft component, a satellite component, or a rocket piping. The workpiece may be manufactured by additive manufacturing.
The groove portion of the workpiece extends, for example, from the left end to the right end of one surface of the workpiece. The groove portions open on the left and right end faces at both ends. The groove may extend linearly. The groove may extend in a bent manner. The cross-sectional shape of the groove portion is, for example, a U-shape or a V-shape. The cross-sectional shape of the groove may be constant in width from the bottom to the opening. The cross-sectional shape of the groove portion may vary in width from the bottom portion to the opening portion. The cross-sectional shape of the groove portion may be constant along the direction in which the groove portion extends. The cross-sectional shape of the groove portion may vary along the direction in which the groove portion extends. The workpiece may have a single groove. The workpiece may have a plurality of grooves.
When the workpiece is a gear, the workpiece may be a spur gear, a helical gear, an inner gear, a double helical gear, or a bevel gear, etc. in which the teeth (tooth grooves) are arranged on a circumference. When the workpiece is a gear, the workpiece may be a rack in which the teeth (tooth grooves) are arranged on a straight line. The rack can be regarded as a gear with an infinite radius.
The rectifying portion of the guide member is, for example, a groove extending in the front-rear direction. The rectifying portion is, for example, a groove extending from the rear end to the front end of one surface of the guide member. The rectifying portion opens to the front and rear end faces at both ends. The rectifying portion may extend linearly. The rectifying portion may extend in a bent manner. When the rectifying portion is a groove, the cross-sectional shape of the rectifying portion is, for example, a U-shape or a V-shape. The cross-sectional shape of the rectifying portion may be constant in width from the bottom portion to the opening portion. The cross-sectional shape of the rectifying portion may vary in width from the bottom portion to the opening portion. The cross-sectional shape of the rectifying portion may be constant along the direction in which the rectifying portion extends. The cross-sectional shape of the rectifying portion may vary along the direction in which the rectifying portion extends. The rectifying portion may be formed of a single groove. The rectifying portion may include a plurality of grooves.
The closing portion of the guide member is, for example, a wall disposed at the front end of the rectifying portion. The closing portion may protrude further toward the workpiece than the rectifying portion. In the closing portion, a portion integral with a portion that closes the front end of the rectifying portion may protrude toward the workpiece. The closing portion may include a member separate from a portion that closes the front end of the rectifying portion, and the separate member may protrude toward the workpiece.
The ejection diameter of the nozzle is, for example, 0.5 mm to 3 mm. The ejection pressure of the jet is, for example, 10 MPa to 200 MPa.
The inclination angle of the jet in the ejection direction may be less than 45 degrees.
The nozzle may be moved in the left-right direction by fixing the position of the workpiece in the left-right direction. The workpiece may be moved in the left-right direction by fixing the position of the nozzle in the left-right direction.
When the workpiece is a gear with circumferentially arranged teeth (tooth grooves), the gear may be rotated about its central axis in order to move the tooth grooves in the front-rear direction.
When the workpiece is a gear (rack) in which the teeth (tooth grooves) are arranged in a straight line, the gear may be moved in parallel in the front-rear direction for moving the tooth grooves in the front-rear direction.
When rotating or moving the gear that is the workpiece, the rotation or movement of the gear and the movement of the nozzle or the gear in the left-right direction may be synchronized. For example, the nozzle or the gear may be moved in the left-right direction every time the gear is rotated by one rotation.
According to the cavitation processing method and the cavitation processing apparatus of the present invention, the cavitation processing can be performed on the bottom portion of the groove of the workpiece.
As shown in
As will be described later, the ejection member 20 includes a nozzle 23. The front, rear, left, and right sides are determined based on the direction viewed from the nozzle 23. Specifically, a direction away from the nozzle 23 is a front direction, and a direction approaching the nozzle 23 is a rear direction. In the present embodiment, both the front-rear direction and the left-right direction are horizontal directions. That is, in
The spur gear 50a is metallic. As shown in
As shown in
As shown in
As shown in
The supply pipe 21 is, for example, a straight pipe extending in the up-down direction. The processing liquid 11 supplied from the high-pressure fluid supply source 60 passes through the inside of the supply pipe 21. The high-pressure fluid supply source 60 may be, for example, a pump.
The outlet pipe 22 is connected to a lower end portion of the supply pipe 21. The outlet pipe 22 has a variable angle with respect to the supply pipe 21. The orientation of the distal end of the outlet pipe 22 can be adjusted in a range of at least 0 degrees to 90 degrees (vertically downward) with respect to the front-rear direction.
The nozzle 23 is connected to a distal end of the outlet pipe 22. The nozzle 23 ejects the jet C1 of the processing liquid 11. Changing the direction of the outlet pipe 22 changes the ejection direction of the jet C1. The processing liquid 11 is supplied from the high-pressure fluid supply source 60 to the nozzle 23 through the supply pipe 21 and the outlet pipe 22. The jet C1 contains many cavities. The ejection member 20 is movable in three axial directions in the horizontal direction (the front-rear direction and the left-right direction) and the up-down direction. The ejection velocity (pressure) of the jet C1, the ejection angle, and the 3-axis motion of the ejection member 20 are controlled by a control device (not shown). The ejection diameter (inner diameter) of the nozzle 23 is, for example, 0.5 mm to 3 mm.
As shown in
The base portion 31 is a rectangular parallelepiped block that is elongate in the front-rear direction. As shown in
As shown in
The closing portion 33 has a rectangular plate-shaped wall portion 331. The wall portion 331 is attached to the front end surface of the base portion 31. The wall portion 331 serves as a wall and closes the front end of the rectifying groove 322. The rear surface of the wall portion 331 is a vertical plane. A front side surface of the wall portion 331 may have an upper end portion that is inclined with respect to a vertical plane. That is, the upper end portion of the wall portion 331 has a tapered shape toward upward. The upper edge portion 332, which is an upper edge portion of the wall portion 331, extends in the left-right direction. The upper edge portion 332 protrudes upward from the upper end of the protrusion 321 of the rectifying portion 32. The protruding height of the upper edge portion 332 with respect to the upper end of the protrusion 321 may be shorter than the depth of the rectifying groove 322. The rear surface of the wall portion 331 may be inclined with respect to the vertical plane.
As shown in
As shown in
The cavitation processing apparatus 100 configured as described above can eject the jet C1 to the spur gear 50a. In the present embodiment, the tooth bottom 54 of all the tooth grooves 53 of the spur gear 50a are regions to be cavitated. That is, the tooth bottom 54 of all the tooth grooves 53 of the spur gear 50a is effectively cavitated.
As shown in
During the cavitation processing, the spur gear 50a is rotated in order to process all of the circumferentially aligned tooth bottoms 54. The tooth bottom 54 of the tooth groove 53 facing the front end portion of the rectifying groove 322 serves as a processing target of the cavitation processing. For example, as shown in
As the cavity grows and collapses in the jet C1, the strength of the cavitation processing changes according to the distance from the nozzle 23. The strength of the cavitation processing is, for example, the strength of the compressive residual stress applied and the density and depth of the dimples formed on the surface. When the cavitation processing is performed, the strongest processing is performed at the point where the distance from the nozzle 23 is the most suitable distance, and the degree of the processing becomes weaker as the distance from the point increases. The suitable distance for the cavitation processing is, for example, a distance of about 40 to 100 times the diameter of the nozzle 23. When the nozzle 23 has a 1 mm diameter, it is desirable that the distance between the nozzle 23 and the tooth bottom 54 is 40 mm to 100 mm. This distance is the distance actually passed by the jet C1. That is, as indicated by the broken-line arrow C11 to C13 in
During the cavitation processing, the nozzle 23 (the ejection member 20) may be moved to the left and right. In the cavitation processing, the strongest processing is performed on the central axis of the jet C1, and the degree of the processing becomes weaker as the distance from the central axis to the left and right becomes larger. When the width of the spur gear 50a in the left-right direction is wider than the predetermined width, an adequate cavitation processing is not performed on a portion of the tooth bottom 54 that is away from the center axis of the jet C1 in the left-right direction. In this case, by moving the nozzle 23 to the left and right as shown in
The nozzle 23 may be moved continuously. The nozzle 23 may be moved intermittently. For example, the nozzle 23 may be moved so that its position in the left-right direction coincides with each of the rectifying grooves 322. In addition, the spur gear 50a (holding member 40) may be moved to the left and right while the nozzle 23 is fixed. That is, the lateral position of the nozzle 23 and the spur gear 50a may be relatively changed.
The steps of the cavitation processing method of the present embodiment performed by the cavitation processing apparatus 100 are as follows.
First, the processing liquid 11 is stored in the tank 10. The amount of the processing liquid 11 to be stored is an amount that allows the spur gear 50a to be immersed in a sufficient depth. The sufficient depth is, for example, 300 mm to 500 mm. At this time, the ejection member 20, the guide member 30, and the holding member 40 are positioned above the liquid level of the processing liquid 11.
Next, the spur gear 50a is fixed to the holding member 40. The spur gear 50a is held such that the central axis 55 extends in the left-right direction.
Next, the positions of the ejection member 20, the guide member 30, and the spur gear 50a are set. That is, the orientation of the nozzle 23, the distance between the nozzle 23 and the spur gear 50a, the distance between the closing portion 33 and the spur gear 50a, and the like are set as appropriate.
Next, the ejection member 20, the guide member 30, and the holding member 40 (spur gear 50a) are moved downward to be immersed in the processing liquid 11 stored in the tank 10.
Next, the high-pressure fluid supply source 60 is activated to eject the jet C1 from the nozzle 23. The jet C1 reaches the tooth bottom 54 of the tooth groove 53 through the guide member 30, and performs the cavitation processing.
Next, the spur gear 50a is rotated. The nozzle 23 is moved to the left and right as necessary.
In this way, the jet C1 is ejected from the nozzle 23, the spur gear 50a is rotated, and the nozzle 23 is moved as needed. The cavitation processing is thus performed on the tooth bottom 54. As the jet C1 flows through the rectifying groove 322, the jet C1 is caused to collide with the tooth bottom 54 of the processing target without being distributed to the surroundings.
The order of the steps of the cavitation processing method according to the present embodiment is not limited to the above-described order. For example, the ejection member 20, the guide member 30, and the holding member 40 may be installed in the tank 10 from the beginning. In this case, the processing liquid 11 may be stored in the tank 10 after fixing the spur gear 50a to the holding member 40 and setting the positions of the ejection member 20, the guide member 30, and the spur gear 50a to each other. The spur gear 50a may be rotated from the beginning of the cavitation processing. From the beginning of the cavitation processing, the nozzle 23 may be moved to the left and right. Rotation of the spur gear 50a and movement of the nozzle 23 may be performed simultaneously.
The configuration of the spur gear 50a is exemplary. The cavitation processing method according to the present embodiment can also be applied to a spur gear in which the shapes of the tooth 51, the tooth groove 53, and the tooth bottom 54 are different from the above example. The cavitation processing method according to the present embodiment can also be applied to gears other than spur gears. Furthermore, the cavitation processing method according to the present embodiment can also be applied to a workpiece having a groove portion other than a gear.
As shown in
The rack 50b, which is a workpiece of the present embodiment, can be regarded as a gear having an infinite radius. The rack 50b is metallic. The rack 50b has a plurality of teeth 51. The plurality of teeth 51 are arranged on a straight line. The tooth 51 has a tapered shape toward the distal end. The distal end of the tooth 51 is a flat tooth distal end surface 52. A tooth groove 53 is formed between adjacent teeth 51. The tooth groove 53 has a shape in which the groove width increases toward the opening. The bottom of the tooth groove 53 is the tooth bottom 54. The tooth bottom 54 is a surface that connects the roots of the teeth 51 adjacent to each other on both sides. The tooth bottom 54 is a curved surface that is concave toward the opening of the tooth groove 53. The tooth groove 53 is a groove portion of the workpiece. The tooth bottom 54 is the bottom of the groove. The tooth bottom 54 is a target portion of the cavitation processing.
The rack 50b is arranged such that the plurality of teeth 51 are arranged in front-rear direction and protrude downward. Between the front and rear teeth 51, the tooth groove 53 extending in the left-right direction is formed. The tooth groove 53 opens downward. In a tooth groove 53, the rear side of the tooth distal end surface 52 of the front tooth 51 is a front edge 56 which is a front edge portion of the tooth groove 53. In a tooth groove 53, the front side of the tooth distal end surface 52 of the rear tooth 51 is a rear edge 57 which is a rear edge portion of the tooth groove 53.
The holding member 40 of the cavitation processing apparatus 100 according to the present embodiment includes a holding table 42. The holding table 42 fixes the rack 50b with fasteners such as bolts and clamps, or fixes the rack 50b by clamping. The holding table 42 is movable in the front-rear direction while holding the rack 50b.
The holding table 42 and the rack 50b may be inclined so as to lower the front. At this time, the holding table 42 may move in the inclination direction of the holding table 42. The holding table 42 may move in the front-rear direction.
In the present embodiment, the cavitation processing is performed on all the tooth bottoms 54 of the rack 50b.
The step of the cavitation processing method according to the present embodiment is different from the step of the cavitation processing method of the first embodiment in that the rack 50b (holding table 42) is moved in the front-rear direction, and the other steps are substantially the same.
The rack 50b (holding table 42) is moved in the front-rear direction in order to perform the cavitation processing to all the tooth bottoms 54 arranged on a straight line. For example, as shown in
The rack 50b may be moved continuously. The rack 50b may be moved intermittently. For example, the rack 50b may be moved by a distance corresponding to one tooth 51.
In this way, the jet C1 is ejected from the nozzle 23, the rack 50b is moved, and the nozzle 23 is moved as needed. The cavitation processing is thus performed on the tooth bottom 54 of the rack 50b.
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are the subject of the present invention. While the above embodiments have been shown by way of example, those skilled in the art will recognize that various alternatives, modifications, variations, and improvements can be made from the disclosure herein, which fall within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-127750 | Aug 2023 | JP | national |
