The present invention relates to a shot peening processing method.
A shot peening processing method is used to provide a metal surface layer with compressive residual stress. In the shot peening processing method, media (shot media) is projected onto a work.
In a conventional shot peening processing method, after a combination of a shot peening processing apparatus and media is determined, a process condition is determined such that intensity and coverage required for a work can be achieved. An effective and systematic method for reducing a required time for shot peening process is required.
Japanese Patent Publication (JP-P2006-205342A) discloses a conventional method for setting shot peening condition. A relation between weight of shot media projected per unit time and an arc height value when coverage is 100% is obtained by using an air blast type shot-peening apparatus. When the weight of shot media projected per unit time is greater than a certain value, the arc height value is greatly reduced as the weight of shot media projected per unit time is increased. Based on the value, an optimum value of weight of shot media projected per unit time is set.
An objective of the present invention is to provide a method for setting shot-peening process condition and a method for manufacturing metal part which reduce required time for shot-peening process.
In a first aspect of the present invention, a method for setting shot-peening process condition includes: a step of obtaining, for each of a plurality of peening conditions for a first combination as a combination of a shot-peening processing apparatus and media, a saturation time based on a saturation curve indicating change in arc height value of Almen strip against projection time; and a step of determining a first optimum peening condition corresponding to the first combination based on the saturation time.
Preferably, condition factors of the plurality of peening conditions include a first condition factor and a second condition factor. The plurality of peening conditions include: a first peening condition; a second peening condition different from the first peening condition in only a level of the first condition factor; a third peening condition; and a fourth peening condition different from the third peening condition in only a level of the second condition factor. The step of determining the first optimum peening condition based on the saturation time includes: a step of determining a level of the first condition factor in the first optimum peening condition based on a first saturation time under the first peening condition and a second saturation time under the second peening condition; and a step of determining a level of the second condition factor in the first optimum peening condition based on a third saturation time under the third peening condition and a fourth saturation time under the fourth peening condition.
Preferably, the shot-peening processing apparatus projects media from a nozzle by using air. The first condition factor and the second condition factor are arbitrary two selected from flow rate of media, pressure of air, distance between the nozzle and a surface to be processed, angle between the nozzle and a surface to be processed, inner diameter of the nozzle, and movement speed of the nozzle.
Preferably, the shot-peening processing apparatus projects media by using an impeller. The first condition factor and the second condition factor are arbitrary two selected from rotation speed of the impeller, distance between the impeller and a surface to be processed, angle between the impeller and a surface to be processed, size of a projection outlet, movement speed of a work, and rotation speed of a work.
Preferably, the above method for setting shot-peening process condition includes: a step of the shot-peening processing apparatus projecting media to a test piece under the first optimum peening condition; a step of obtaining a relation between a distribution of dimpled area ratio in the test piece and projection time; and a step of obtaining, based on the relation between the distribution of the dimpled area ratio and the projection time, a relation between area or width of a region of the test piece, in which the dimpled area ratio is saturated, and the projection time. The dimpled area ratio indicates an area occupied by dimples formed by media per unit area.
Preferably, the above method for setting shot-peening process condition further includes a step of determining a spot movement condition based on the relation between the area or width and the projection time. The spot movement condition indicates a pitch of movement trajectories along which a spot moves. The movement trajectories are parallel to each other. The spot is a region of a work, which is hit by media when the shot-peening processing apparatus processes the work.
Preferably, when intensity corresponding to the first optimum peening condition does not match intensity required for a work, the above method for setting shot-peening process condition further includes: a step of obtaining a saturation time for each of a plurality of peening conditions for a second combination as a combination of a shot-peening processing apparatus and media; and a step of determining a second optimum peening condition corresponding to the second combination based on the saturation time corresponding to the second combination.
Preferably, the above method for setting shot-peening process condition further includes a step of obtaining intensity under the first optimum peening condition.
Preferably, the above method for setting shot-peening process condition further includes: a step of obtaining a coverage time as a projection time required for a coverage of 100% for each of the plurality of peening conditions by using the Almen strip used in the step of obtaining the saturation time; a step of determining a third optimum peening condition corresponding to the first combination based on the coverage time; and a step of determining a fourth peening condition based on the first peening condition and the third peening condition.
In a second aspect of the present invention, a method for setting shot-peening process condition includes: a step of a shot-peening processing apparatus projecting media onto a test piece; a step of obtaining a relation between a distribution of dimpled area ratio in the test piece and projection time; and a step of obtaining, based on the relation between the distribution of the dimpled area ratio and the projection time, a relation between area or width of a region of the test piece, in which the dimpled area ratio is saturated, and the projection time. The dimpled area ratio indicates area occupied by dimples formed by media per unit area.
In a third aspect of the present invention, a method for setting shot-peening process condition includes: a step of obtaining, for each of a plurality of peening conditions for a first combination as a combination of a shot-peening processing apparatus and media, a coverage time as a projection time required for a coverage of 100% based on a saturation curve indicating change in coverage of Almen strip against projection time; and a step of determining an optimum peening condition corresponding to the first combination based on the coverage time.
Preferably, condition factors of the plurality of peening conditions include a first condition factor; and a second condition factor. The plurality of peening conditions include: a first peening condition; a second peening condition different from the first peening condition in only a level of the first condition factor; a third peening condition; and a fourth peening condition different from the third peening condition in only a level of the second condition factor. The step of determining the optimum peening condition based on the coverage time includes: a step of determining a level of the first condition factor in the optimum peening condition based on a first coverage time under the first peening condition and a second coverage time under the second peening condition; and a step of determining a level of the second condition factor in the optimum peening condition based on a third coverage time under the third peening condition and a fourth coverage time under the fourth peening condition.
In a fourth aspect of the present invention, a method for manufacturing metal part includes: a step of determining a shot-peening process condition; and a step of processing a work based on the shot-peening process condition. The step of determining the shot-peening process condition includes: a step of obtaining, for each of a plurality of peening conditions for a first combination as a combination of a shot-peening processing apparatus and media, a saturation time based on a saturation curve indicating change in arc height value of Almen strip against projection time; and a step of determining a first optimum peening condition corresponding to the first combination based on the saturation time.
In a fifth aspect of the present invention, a method for manufacturing metal part includes: a step of determining a shot-peening process condition; and a step of processing a work based on the shot-peening process condition. The step of determining the shot-peening process condition includes: a step of a shot-peening processing apparatus projecting media onto a test piece; a step of obtaining a relation between a distribution of dimpled area ratio in the test piece and projection time; a step of obtaining, based on the relation between the distribution of the dimpled area ratio and the projection time, a relation between area or width of a region of the test piece, in which the dimpled area ratio is saturated, and the projection time; and a step of determining a spot movement condition based on the relation between the area or width and the projection time. The spot movement condition indicates a movement condition of a spot as a region of the work, which is hit by media when the shot-peening apparatus processes the work.
In a sixth aspect of the present invention, a method for manufacturing metal part includes: a step of determining a shot-peening process condition; and a step of processing a work based on the shot-peening process condition. The step of determining the shot-peening process condition includes: a step of obtaining, for each of a plurality of peening conditions for a first combination as a combination of a shot-peening processing apparatus and media, a coverage time as a projection time required for a coverage of 100% based on a saturation curve indicating change in coverage of Almen strip against projection time; and a step of determining an optimum peening condition corresponding to the first combination based on the coverage time.
According to the present invention, there are provided a method for setting shot-peening process condition and a method for manufacturing metal part which reduce required time for shot-peening process.
The above and other objects, advantages, and features of the present invention will be more apparent from the description of embodiments taken in conjunction with the accompanying drawings, in which:
With reference to the accompanying drawings, embodiments of a method for setting shot-peening process condition and a shot-peening processing method according to the present invention will be described below.
With reference to
With reference to
With reference to
In the step S21, assessment target condition factors are determined. For example, assessment target condition factors in a case of an air blast type shot-peening processing apparatus are: flow rate (kg/min) of media; air pressure (MPa); distance (projection distance) between a nozzle as a projection unit of the air blast type shot-peening processing apparatus and a surface of a work; angle (projection angle) between the nozzle and the work surface; inner diameter of the nozzle; and movement speed of the nozzle. For example, assessment target condition factors in a case of a mechanical type shot-peening processing apparatus are: rotation speed (rpm) of an impeller as a projection unit of the mechanical type shot-peening processing apparatus; distance (projection distance) between the impeller and a surface of a work; angle (projection angle) between the impeller and the work surface; size of a projection outlet from which the media is injected to the work surface; movement speed of the work; and rotation speed (rpm) of the work.
With reference to
In the step S22, a plurality of peening conditions is determined. For example, condition factors of the plurality of peening conditions include the flow rate, the pressure, the angle, the distance and the like as the condition factors determined in the step S21.
In the step S23, a saturation curve indicating change in arc height value of Almen strip against projection time is prepared for each of the plurality of peening conditions determined in the step S22.
In the step S24, intensity and saturation time for each of the peening conditions determined in the step S22 are obtained based on the saturation curves obtained in the step S23. With reference to
In the step S25, an optimum level of each condition factor is determined such that the shortest saturation time is attained. For example,
In the step S26, an optimum peening condition corresponding to the combination of the shot-peening processing apparatus and the media determined in the step S11 is determined. The optimum peening condition is a combination of the optimum levels of the respective condition factors, which are determined in the step S25.
The peening condition 1-2 shown in
After the step S26, the method proceeds to the step S30.
As mentioned above, based on the saturation time, the optimum peening condition is determined under which a processing time is short in processing with the use of the combination determined in the step S11. In general, it is considered that coverage time required for the coverage of 100% is shorter as the saturation time is shorter. The saturation time is easily determined as compared to the coverage time.
By optimizing the spot movement condition, the processing time can further be reduced. The step S30 of determining a spot movement condition will be described below.
With reference to
The step S31 will be described.
In the step S31, the surface of the test piece 5, onto which the projection is performed, is observed by using a magnifying glass, and dimpled area ratio is calculated for each of a plurality of area ratio calculation regions 7 defined on the surface of the test piece 5. The plurality of area ratio calculation regions 7 are arranged on the both sides of the center line 4 of the test piece 5 along a straight line crossing the center line 4 at a center position 6. The plurality of area ratio calculation regions 7 are regions of the same shape and the same size. Each area ratio calculation region 7 is a rectangular region of 2.56 mm square, for example. Numbers indicating measurement locations of the area ratio calculation regions 7 are shown in the figure. The absolute value of the number is greater as the location is farther from the center position 6. The sign of the number is positive when the measurement location is in one side of the center line 4 or negative when the measurement location is in the other side of the center line 4. The dimpled area ratio indicates area occupied by impressions (dimples) formed by the media per unit area.
In the step S31, a relation between dimpled area ratio distribution in the test piece 5 and projection time is obtained.
In the step S32, based on the relation between dimpled area ratio distribution and projection time shown in
In the step S33, a spot movement condition is determined based on the relation between effective process width and projection time of
Another example of the step S30 will be described.
When a work to be processed has concretely been determined, it is preferable that the step S13 should be performed after the step S20 and before the step S30.
In the step S20, it is also possible to fix a level of a specific condition factor and then determine optimum levels of the other condition factors. For example, when projection onto the entire of the surface of work is impossible with the projection angle of 90 degrees due to many convexes and concaves of the surface of the work, the projection angle is fixed at 45 degrees and then optimum levels of the other condition factors are determined.
A method for setting shot-peening process condition according to a second embodiment of the present invention is the same as the method for setting shot-peening process condition according to the first embodiment except for a point that the step S20 is replaced by a step S210 of determining optimum peening condition.
As shown in
In the step S213, based on the saturation times obtained in the step S212 and the saturation times obtained in the step S24, optimum levels of the respective condition factors are determined.
In the step S214, an optimum peening condition corresponding to the combination of the shot-peening processing apparatus and the media determined in the step S11 is determined. The optimum peening condition is a combination of the optimum levels of condition factors determined in the step S213.
A method for setting shot-peening process condition according to a third embodiment of the present invention is the same as the method for setting shot-peening process condition according to the first or second embodiment except for points that the step S20 is replaced by a step S220 and the step S30 is eliminated.
With reference to
In the step S222, optimum levels of the respective condition factors are determined such that the shortest coverage time is attained.
In the step S223, an optimum peening condition corresponding to the combination of the shot-peening processing apparatus and the media determined in the step S11 is determined. The optimum peening condition is a combination of the optimum levels of condition factors determined in the step S222.
In the step S224, an optimum peening condition is determined based on the optimum peening condition determined in the step S26 and the optimum peening condition determined in the step S223. For example, the optimum peening condition of the step S224 may be determined by selecting one of the optimum peening condition determined in the step S26 and the optimum peening condition determined in the step S223, or the optimum peening condition of the step S224 may be determined by modifying the optimum peening condition determined in the step S26 based on the optimum peening condition determined in the step S223.
In the present embodiment, the work is processed in the step S2 based on the optimum peening condition determined in the step S224.
There is a possibility that the coverage time under the optimum peening condition determined based on only saturation time is long. According to the present embodiment, the optimum peening condition is determined such that a short coverage time is certainly attained.
Note that the optimum peening condition may be determined based on only coverage time without determining the optimum peening condition based on saturation time.
The shot-peening processing methods according to the above embodiments can be applied to a method for manufacturing metal part.
The present invention has been described with reference to the embodiments; however, the present invention is not limited to the above embodiments. Various modifications can be applied to the above embodiments.
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-050673, filed on Mar. 4, 2009, the disclosure of which is incorporated herein in its entirely by reference.
Number | Date | Country | Kind |
---|---|---|---|
2009-050673 | Mar 2009 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2010/051202 | 1/29/2010 | WO | 00 | 9/20/2011 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2010/100984 | 9/10/2010 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2350440 | Almen | Jun 1944 | A |
2958925 | Roberts | Nov 1960 | A |
3950642 | Feld | Apr 1976 | A |
4454740 | Neal et al. | Jun 1984 | A |
5172580 | Thompson | Dec 1992 | A |
5293320 | Thompson et al. | Mar 1994 | A |
5460025 | Champaigne | Oct 1995 | A |
5487543 | Funk | Jan 1996 | A |
5507172 | Thompson et al. | Apr 1996 | A |
5592840 | Miyasaka | Jan 1997 | A |
6315646 | Hoyashita | Nov 2001 | B1 |
6319101 | Vago | Nov 2001 | B1 |
6640596 | Yamamoto et al. | Nov 2003 | B2 |
7065479 | Mika et al. | Jun 2006 | B2 |
7159425 | Prevey et al. | Jan 2007 | B2 |
7300622 | Lu et al. | Nov 2007 | B2 |
7458881 | Kawashima et al. | Dec 2008 | B2 |
20030005736 | Inoue et al. | Jan 2003 | A1 |
20050204528 | Culp et al. | Sep 2005 | A1 |
20100011826 | Buehler et al. | Jan 2010 | A1 |
Number | Date | Country |
---|---|---|
1-210269 | Aug 1989 | JP |
2003-159651 | Jun 2003 | JP |
2004-142007 | May 2004 | JP |
2006-205342 | Aug 2006 | JP |
400267 | Aug 2000 | TW |
414738 | Dec 2000 | TW |
544376 | Aug 2003 | TW |
Entry |
---|
Notice of Allowance issued Sep. 10, 2013 in corresponding Chinese Patent Application No. 201080010707.0 with partial English translation. |
Taiwanese Office Action issued Aug. 30, 2013 in corresponding Taiwanese Patent Application No. 99102660 with partial English translation. |
Japanese Decision to Grant a Patent issued Jul. 31, 2012 in corresponding Japanese Patent Application No. 2009-050673 with English translation. |
Taiwanese Notice of Allowance issued Jan. 22, 2014 in corresponding Taiwanese Patent Application No. 099102660 with English translation. |
International Search Report issued Apr. 27, 2010 in International (PCT) Application No. PCT/JP2010/051202. |
Extended European Search Report issued Nov. 27, 2014 in corresponding European Patent Application No. 10748581.5. |
Decision to grant a European patent pursuant to Article 97(1) EPC issued Jan. 8, 2016 in corresponding European Application No. 10748581.5. |
Number | Date | Country | |
---|---|---|---|
20120017661 A1 | Jan 2012 | US |