CN108698201B

CN108698201B - Shot peening device

Info

Publication number: CN108698201B
Application number: CN201780011608.6A
Authority: CN
Inventors: 冈田秀树; 横田大介; 森山千里; 秋山聪史; 驹崎雅也; 永安刚
Original assignee: NHK Spring Co Ltd
Current assignee: NHK Spring Co Ltd
Priority date: 2016-02-23
Filing date: 2017-02-23
Publication date: 2020-06-12
Anticipated expiration: 2037-02-23
Also published as: WO2017146173A1; JP6582119B2; US20180354097A1; CN108698201A; EP3421176A4; EP3421176A1; JPWO2017146173A1

Abstract

A shot peening device (50) is provided with a turntable (79) which rotates around a revolution axis (X1), holding mechanisms (81, 82) which move together with the turntable (79), a pressurizing mechanism (93) which compresses a coil spring (1), a rotation mechanism (100) which rotates the coil spring (1), a blasting mechanism (57) which blasts steel shots to the compressed coil spring (1), load sensors (96, 97) which detect a load applied to the coil spring (1), and a control unit (98). By inputting signals output from the load sensors (96, 97) to the control unit (98), it is possible to detect a change with time in the load applied to the coil spring (1) during shot peening.

Description

Shot peening device

Technical Field

The present invention relates to a shot peening apparatus that performs shot peening (shot peening) in a state where a coil spring is compressed.

Background

In order to improve the durability of a coil spring used for a suspension spring of an automobile suspension device or the like, a method of applying compressive residual stress to the coil spring by shot peening is known. An example of a conventional shot peening apparatus is disclosed in patent document 1. The shot peening apparatus ejects steel shots from a centrifugal accelerator (impeller) to a coil spring while conveying the coil spring. A conventional shot peening apparatus is also described in patent document 2. The shot peening apparatus compresses a coil spring and performs shot peening in a state in which stress is applied thereto. That is, the shot peening apparatus generates a very large compressive residual stress in the coil spring by shot peening. Another patent document 3 describes an apparatus for shot peening while compressing a coil spring on a rotating turntable.

Prior art documents

Patent document

[ patent document 1 ] patent publication No. 2002-361558

[ patent document 2 ] patent publication No. 2003-117830

[ patent document 3 ] patent publication No. 2015-77638.

Disclosure of Invention

Problems to be solved by the invention

As in patent document 1, in a shot peening device for peening only a steel shot on a coil spring, there is room for improvement in generating a large compressive residual stress in the coil spring. As in patent documents 2 and 3, in an apparatus for shot peening a coil spring in a compressed state, depending on the shape of the coil spring (particularly, the shape of the support ring), the coil spring may be supported in an unstable state. This may prevent the shot peening from being accurately performed due to the instability of the coil spring.

Accordingly, an object of the present invention is to provide a shot peening apparatus capable of performing shot peening in a state where a desired stress is applied to a coil spring.

Means for solving the problems

In one embodiment, the shot peening apparatus is equipped with a turntable mechanism including a turntable that rotates about a revolution axis, a revolution mechanism for rotating the turntable mechanism, a holding mechanism for holding a lower support turn and an upper support turn of the coil spring in a state where the coil spring is made to stand upright and moving around the revolution axis together with the turntable, a rotation mechanism for rotating the holding mechanism around the rotation axis, a pressurizing mechanism for compressing the coil spring while the coil spring is held in the holding mechanism, a load detector such as a load cell for detecting a compression load that is pressurized on the coil spring by the pressurizing mechanism, the injection mechanism is configured to inject a shot toward the compressed coil spring, and the control unit (for example, a personal computer) is configured to detect a change in the load based on a signal output from the load detector.

One example of the load detector is a load sensor disposed in a load transmission path between the pressing mechanism and the holding mechanism. The control unit may include a device for storing a change in the load with time. Alternatively, the control unit may have a display unit that displays a change in the load with time.

The control unit may be provided with a device that notifies when the load exceeds an allowable range while the injection mechanism injects the steel shot into the coil spring. The control unit may be provided with a computer program for controlling the pressurizing mechanism so that the load approaches a predetermined value while the injection mechanism injects the steel shot into the coil spring.

Effects of the invention

According to the present invention, by shot peening (shot peening) the coil spring in a state where a desired stress is applied to the coil spring, a compression residual stress can be formed in the coil spring and a coil spring with stable quality can be obtained.

Drawings

Fig. 1 is a perspective view showing one example of a coil spring.

Fig. 2 is a flowchart showing an example of a coil spring manufacturing process.

FIG. 3 is a perspective view schematically showing the 1 st shot peening apparatus.

Fig. 4 is a perspective view showing a part of the transfer device and an example of the transfer mechanism (robot).

FIG. 5 is a front view of a part of a2 nd shot peening apparatus according to an embodiment.

FIG. 6 is a longitudinal sectional view of the shot peening apparatus shown in FIG. 5.

FIG. 7 is a cross-sectional view of the shot peening apparatus shown in FIG. 5.

Fig. 8 is a perspective view of a lower support base of the shot peening apparatus shown in fig. 5.

Fig. 9 is a perspective view of a lower support base of the shot peening apparatus shown in fig. 5.

FIG. 10 is a flowchart showing the operation of the shot peening apparatus shown in FIG. 5.

Fig. 11 is a diagram showing an example of a change with time in a load generated in shot peening in a certain temperature range.

Fig. 12 is a diagram showing another example of a change with time in a load generated in shot peening in a certain temperature range.

Description of the symbols

1-coil spring, 1a, 1 b-support ring, 2-bare wire, 10-1 shot-peening device, 50-2 shot-peening device, 52-turntable mechanism, 55-1 blasting unit, 56-2 blasting unit, 57-1 blasting mechanism, 61-1 chamber, 62-2 chamber, 79-turntable, 80-shaft mechanism, 81-1 holding mechanism, 82-2 holding mechanism, 93-pressurizing mechanism, 94, 95-pressurizing unit, 96, 97-load sensor (load detector), 98-control part, 100-rotation mechanism, 110-information processing device, 111-operation part, and X-rotation part, 24-rotation shaft, 52-rotation part, 52-rotation shaft, and 3-rotation shaft, and X-rotation part, 24-rotation shaft, and X-rotation part, and X-2-rotation part, and X-.

Detailed description of the preferred embodiments

A coil spring processing apparatus including the shot peening apparatus 50 according to one embodiment will be described with reference to the drawings of fig. 1 to 12.

Fig. 1 shows an example of a coil spring 1. The coil spring 1 is made of a bare wire (metal wire) 2 wound in a spiral shape. One end and the other end of the coil spring 1 are respectively formed with

support rings

1a and 1 b. The relative positional relationship of the one end terminal 1c and the other end terminal 1d is constant depending on the type of the coil spring 1.

In this specification, a position from the end 1c of the coil spring 1 to the position rotated about the axis X1 is referred to as "a position in the coil circumferential direction" or "a position in the winding direction". The coil spring 1 is a cylindrical coil spring as an example, but may be a coil spring having various shapes such as a barrel-shaped coil spring, an hourglass coil spring, a conical coil spring, or a coil spring having different pitches depending on the structure of the suspension device. The

support rings

1a and 1b may have a negative pitch (negative pitch angle) or a positive pitch (positive pitch angle).

Fig. 2 shows an example of a manufacturing process of the coil spring 1. In the molding step S1 in fig. 2, the bare wire (metal wire) 2 is wound into a spiral shape by using a winder. In the heat treatment step S2, tempering and annealing are performed to remove the bad stress generated in the bare wire 2 in the molding step S1. For example, the bare wire 2 is heated to, for example, 400 to 450 ℃ and then slowly cooled.

Further, in the 1 st shot peening step S3, the 1 st shot peening is performed, for example, within a certain temperature range by using the residual heat of the heat treatment step S2. In the 1 st shot peening step S3, the 1 st shot is shot by the 1 st shot peening device 10 shown in fig. 3 at a treatment temperature of, for example, 250 to 300 ℃. The No. 1 steel shot is, for example, a cut wire having a particle diameter of 1.1 mm. However, the shot peening device 10 other than the above may be used, and the shot size other than the above (for example, 0.87 to 1.2mm) may be used. In the 1 st shot peening step S3, compressive residual stress is formed from the surface of the coil spring 1 to a deep position. And the oxide film (black skin formed by heat treatment) formed on the surface of the bare wire 2 is removed by the 1 st shot peening step S3.

FIG. 3 schematically shows an example of the 1 st shot peening apparatus 10. The 1 st shot peening apparatus 10 has a pair of

guide rollers

11, 12 and a shot peening device (impeller) 13. The

guide rollers

11 and 12 are provided with a plurality of coil springs 1, and are aligned in a horizontal posture (a posture in which the coil springs are laterally laid down) with their axes C1 horizontal. The coil springs 1 on the

guide rollers

11 and 12 continuously move in the direction of arrow F1 while rotating around the axis C1. Shot SH1 ejected from the shot ejector 13 is ejected to the moving coil spring 1.

Fig. 4 shows a transport device 20 which is part of a coil spring handling device and a robot 21 handling coil springs 1. The conveying device 20 continuously conveys the plurality of coil springs 1 in the direction indicated by the arrow F2. The robot 21 is supported from both sides of the coil spring 1 by an open-close type jig 23 provided at the tip of the arm 22. The robot 21 is an example of a transfer mechanism for moving the coil spring 1.

The robot 21 has a function of storing the positions of the

end portions

1c and 1d of the coil spring 1 supported by the jig 23 in a memory. In order to set the

end portions

1c and 1d of the coil spring 1 supported by the robot 21 at predetermined positions, the positions of the

end portions

1c and 1d may be previously regulated by a positioning device such as a jig.

In the 2 nd shot peening step S4, 2 nd shot peening (shot peening within a certain temperature range) is performed by the shot peening device 50 shown in fig. 5 to 9. The 2 nd shot peening step S4 is performed at a temperature lower than that of the 1 st shot peening step S3 (for example, in a temperature range of 200 to 250 ℃) in a state where the coil spring 1 is compressed. In the 2 nd shot peening step S4, the 2 nd shot is shot over the entire surface of the coil spring 1. The size of the 2 nd shot is smaller than that of the 1 st shot used in the 1 st shot peening step S3. The No. 1 steel shot is, for example, a cut wire having a particle diameter of 0.4 to 0.7 mm. The absolute value of the compressive residual stress in the vicinity of the surface of the bare wire 2 can be increased by the 2 nd shot peening step S4.

The solidifying step S5 is performed as necessary, and then the coil spring 1 is coated in the coating step S6, and finally the finished coil spring 1 is inspected for quality in the inspecting step S7.

The following describes the structure and operation of the 2 nd shot peening apparatus 50 with reference to FIGS. 5 to 9. The 2 nd shot peening device 50 constitutes a part of the coil spring processing device. The 2 nd shot peening device 50 performs shot peening in a temperature range of, for example, 200 to 250 ℃ in a posture in which the coil spring 1 is erected. Here, the "posture in which the coil spring 1 stands" means a state in which the axis C1 of the coil spring 1 is substantially vertical.

FIG. 5 is a front view of a part of the 2 nd shot peening apparatus 50. FIG. 6 is a longitudinal sectional view of the 2 nd shot peening apparatus 50. FIG. 7 is a cross-sectional view of the 2 nd shot peening apparatus 50. The 2 nd shot peening apparatus 50 has a housing 51, a turntable mechanism 52, a blasting mechanism 57 (shown in FIG. 6), a1 st elevating mechanism 58, and a2 nd elevating mechanism 59. The injection mechanism 57 includes the 1 st injection unit 55 and the 2 nd injection unit 56. The 1 st elevation mechanism 58 and the 2 nd elevation mechanism 59 move the

ejection units

55 and 56 in the vertical direction.

The 1 st lifting mechanism 58 and the 2 nd lifting mechanism 59 are respectively composed of

servo motors

58a and 59a and ball screws 58b and 59b, and the

servo motors

58a and 59a are controlled to rotate by a controller. These elevating mechanisms 58, 59 independently move the ejecting

units

55, 56 in the up-down direction by a predetermined stroke Y1, Y2 according to the rotation direction and the rotation degree of the

servomotors

58a, 59a, respectively.

As shown in fig. 6 and 7, the housing 51 has a1 st chamber 61, a2 nd chamber 62, and

intermediate chambers

63 and 64 between the 1 st chamber 61 and the 2 nd chamber 62 formed therein. The 1 st chamber 61 is formed with a coil spring inlet and outlet 65. The coil spring inlet/outlet 65 is an opening for inserting or extracting the coil 1 into or from the outside of the housing 51 into the 1 st chamber 61. The injection port 55a of the 1 st injection unit 55 and the injection port 56a of the 2 nd injection unit 56 are arranged in the 2 nd chamber 62. The shot SH2 is ejected from the ejection ports 55a and 56a toward the coil spring 1.

As shown in fig. 7,

partition walls

70 and 71 are provided between the 1 st chamber 61 and the

intermediate chambers

63 and 64. No partition walls 72, 73 can be provided between the 2 nd chamber 62 and the

intermediate chambers

63, 64. The

intermediate chambers

63, 64 are formed with sealing

walls

74, 75. The sealing

walls

74, 75 prevent the steel shot SH2 sprayed into the 2 nd chamber 62 from heading toward the 1 st chamber 61.

The turntable 52 shown in fig. 5 has a turntable 79, a revolution mechanism 80 (shown in fig. 5), a1 st holding mechanism 81, and a2 nd holding mechanism 82. The turntable 79 rotates about an axis X1 revolving vertically. The revolution mechanism 80 is equipped with a motor. The motor rotates the turntable 79 intermittently and alternately 180 ℃ about the revolution axis X1 in the 1 st direction R1 and the 2 nd direction R2 (as shown in fig. 7). The holding

mechanisms

81, 82 and the dial 79 rotate together about the revolution axis X1. The 1 st holding mechanism 81 has a lower support seat 81a and an upper support seat 81 b. The lower support seat 81a is disposed on the turntable 79. The upper support 81b is disposed above the lower support 81 a. The 2 nd holding mechanism 82 also has a lower support seat 82a and an upper support seat 82 b. The lower support base 82a is disposed on the turntable 79. The upper support 82b is disposed above the lower support 82 a.

The 1 st holding mechanism 81 and the 2 nd holding mechanism 82 are disposed at rotational symmetry positions of 180 ℃ with respect to each other around the revolution axis X1. Support plates 83 and 84 (shown in fig. 7) are disposed behind the 1 st holding mechanism 81 and the 2 nd holding mechanism 82 on the turntable 79.

The lower support base 81a of the 1 st holding mechanism 81 and the lower support base 82a of the 2 nd holding mechanism 82 are provided with a jig 85 for preventing positional deviation. The lower support ring 1a of the coil spring 1 may be fitted in the prevention jig 85. Fig. 8 and 9 show the 1 st holding mechanism 81 and the lower support seat 81 a. The lower support seat 82a of the 2 nd holding mechanism 82 has the same configuration as the lower support seat 81a of the 1 st holding mechanism 81. Therefore, the lower support seat 81a of the 1 st holding mechanism 81 will be described with reference to fig. 8 and 9.

As shown in fig. 8 and 9, the lower support base 81a is provided with a jig 85 for preventing positional deviation. The jig 85 for preventing positional deviation has a plurality of (e.g., 3)

claw members

85a, 85b, 85 c. The

claw members

85a, 85b, 85c are arranged according to the shape, pitch angle, or the like of the support ring 1a so that they can firmly support the support ring 1a of the coil spring 1. For example, the

claw members

85a, 85b, and 85c are arranged at equal intervals (for example, 90 °) in the circumferential direction of the lower support base 81 a. The number of the claw members of the lower-side misalignment preventing jig 85 and the number of the claw members of the upper-side misalignment preventing jig 91 may be other than 3. But the jaw members may also be arranged at other pitches than 90 deg..

The disc-shaped base member 86 has

guide grooves

86a, 86b formed thereon. The

claw members

85a, 85b, 85c are movable along the

guide grooves

86a, 86 b. After the

claw members

85a, 85b, 85c are adjusted to the respective positions of the support ring 1a, the

claw members

85a, 85b, 85c are fixed to the base member 86 by bolts 87 (shown in fig. 9).

Height adjusting members

88, 89 are provided between the base member 86 and the

claw members

85b, 85 c. The

height adjustment members

88, 89 are provided with a thickness T1, T2 corresponding to the pitch angle of the support loops of the coil springs. By the above operation, the support rings of negative pitch can be also stably placed on the

claw members

85a, 85b, 85 c. V-grooves 90 for inserting the support ring 1a are formed in the

claw members

85a, 85b, and 85c, respectively.

The upper support blocks 81b and 82b are provided with a jig 91 for preventing the upper support ring 1b from being displaced. The upper jig 91 for preventing positional deviation has a plurality of (for example, 3) claw members corresponding to the shape or pitch angle of the support ring 1b, like the lower jig 85 for preventing positional deviation. The upper support ring 1b is held in a stable state by these claw members. The upper jig 91 for preventing positional deviation may have a different shape from the lower jig 85 for preventing positional deviation depending on the shape of the support ring 1 b.

The revolution mechanism 80 (shown in fig. 5) rotates the turntable 79 about the revolution axis X1. That is, the revolution mechanism 80 intermittently rotates the turntable 79 by 180 ° alternately in the 1 st direction R1 and the 2 nd direction R2 (shown in fig. 7). When the 1 st holding mechanism 81 is in the position of the 1 st chamber 61, the 2 nd holding mechanism 82 is in the position of the 2 nd chamber 62. When the 2 nd holding mechanism 82 is located at the 1 st chamber 61 position, the 1 st holding mechanism 81 is located at the 2 nd chamber 62 position.

Further, the shot peening device 50 is provided with a pressing mechanism 93 for compressing the coil spring 1 as shown in FIG. 5. The pressing mechanism 93 has

pressing units

94 and 95 for moving the upper support blocks 81b and 82b in the vertical direction. One example of the pressurizing

units

94 and 95 is composed of a ball screw and a servo motor. The

pressing units

94 and 95 can change the compressive load (stress) applied to the coil spring 1 according to the degree of vertical movement of the upper support blocks 81b and 82 b. Other examples of the pressurizing

units

94 and 95 may be used, such as a hydraulic cylinder, which uses a fluid pressure as a driving source.

The 1 st pressurizing unit 94 and the 2 nd pressurizing unit 95 are provided with

load sensors

96 and 97, respectively. These

load sensors

96 and 97 are examples of load detectors. Load sensors (load detectors) 96 and 97 detect a compressive load applied to the coil spring 1 during shot peening, and input an electric signal related to the detected compressive load to the control unit 98. The 1 st load sensor 96 is disposed on a load transmission path between the 1 st pressing unit 94 and the upper support base 81 b. The 2 nd load sensor 97 is disposed on a load transmission path between the 2 nd pressurizing unit 95 and the upper support seat 82 b.

The control unit 98 has a function (computer program) of detecting a change in load based on the outputs of the

load sensors

96 and 97. The control unit 98 has a function of notifying when the load in the shot peening exceeds the allowable range. Further, the control unit 98 compares the load values output from the

load sensors

96 and 97 with a predetermined load value set in advance in the control unit 98. Further, the present invention has a control function of feeding back signals to the 1 st pressurizing means 94 and the 2 nd pressurizing means 95 so that a difference between the load values output from the

load sensors

96 and 97 and a predetermined load value set in the control unit 98 becomes close to zero, that is, a predetermined load is loaded on the coil spring 1 as much as possible.

The shot peening device 50 has a rotation mechanism 100. The rotation mechanism 100 is for rotating the coil spring 1 about the rotation axes X2 and X3. The rotation axes X2 and X3 extend in the vertical direction. The rotation mechanism 100 includes a lower rotation portion 101 and an upper rotation portion 102. The lower rotating portion 101 rotates the

lower support bases

81a and 82a about the rotation axes X2 and X3. The upper rotating portion 102 is used to rotate the upper support bases 81b and 82b about the rotation axes X2 and X3.

The lower rotating portion 101 and the upper rotating portion 102 have a timing belt and a driving source such as a servo motor, respectively. The control unit 98 for controlling the drive source rotates the lower rotating portion 101 and the upper rotating portion 102 in synchronization with each other by the same number of rotations in the same direction. That is, the

lower support blocks

81a and 82a and the upper support blocks 81b and 82b are rotated in the same direction in synchronization with each other by the same number of rotations. The

lower support blocks

81a, 82a and the upper support blocks 81b, 82b can be stopped at the previously set 1 st rotation stop position or 2 nd rotation stop position based on data input in advance to the control unit 98. An example of the 1 st rotation stop position is a position suitable for the robot 21 to transit the coil spring 1 to the holding

mechanisms

81 and 82. An example of the 2 nd rotation stop position is a position suitable for taking out the coil spring 1 from the holding

mechanisms

81 and 82.

An information processing apparatus 110 such as a personal computer is connected to the control unit 98. The information processing apparatus 110 includes an input operation unit 111 and a display unit 112, which can input a product number of a coil spring and various data, and a pointing device 113 such as a mouse. For example, various data (coil diameter, number of windings, length, wire diameter) relating to the coil spring, data relating to the load applied to the coil spring during shot peening, and the like can be input through the input operation unit 111 or the storage medium 114.

The information processing device 110 such as a personal computer or the like is also used to store the temporal change in the load on the coil spring 1 in shot peening. The display unit 112 of the information processing device 110 is used to display the change in load with time during shot peening. The information processing device 110 may also include the control unit 98.

Fig. 7 is a top view of a cross section of the 1 st spray unit 55 and the 2 nd spray unit 56. The 1 st injection unit 55 is equipped with an impeller (turbine) 121 and a distributor 122. The impeller 121 is rotated by the motor 120. The distributor 122 is used to supply the impeller 121 with steel shot SH 2. The 2 nd spraying unit 56 also has an impeller 126 rotated by a motor 125 and a distributor 127 supplying the shot SH2 to the impeller 126.

The 1 st spray unit 55 can move in the up-down direction along the guide member 130 extending in the up-down direction. The guide member 130 is provided at a side portion of the housing 51. The 1 st spray unit 55 reciprocates between a rising position a1 and a falling position B1 separated by a boundary line of the intermediate position N1 by the 1 st lift mechanism 58 (shown in fig. 6). The 2 nd ejection unit 56 may also move in the up-down direction along a guide member 131 extending in the up-down direction. The guide member 131 is provided at a side portion of the housing 51. The 2 nd spraying unit 56 reciprocates between a rising position a2 and a falling position B2 separated by a boundary line of the intermediate position N2 by a2 nd elevating mechanism 59 (shown in fig. 8).

FIG. 10 is a flowchart showing the operation of the shot peening device 50 of the present embodiment.

In step S10 in fig. 10, the lower support seat 81a of the 1 st holding mechanism 81 is stopped in the 1 st chamber 61. The 1 st coil spring 1 is placed (placed) on the lower support base 81a by the robot 21 (see fig. 4). The support ring 1a placed on the lower support base 81a is stopped by a jig 91 (shown in fig. 8 and 9) for preventing displacement. The coil spring 1 between the lower support seat 81a and the upper support seat 81b is compressed by the lowering of the upper support seat 81 b. The 2 nd retention mechanism 82 is now located in the 2 nd chamber 62. The state of the 2 nd holding mechanism 82 is an empty state in which no coil spring is mounted. The coil spring 1 on the left side in fig. 5 is in a free state in which no compression load is applied. The length (free length) of the coil spring 1 in the free state is L1. The coil spring 1 on the right side in fig. 5 shows a state of being compressed to a length L2.

In step S11 in fig. 10, the dial 79 is rotated 180 ° in the 1 st direction. By this rotation, the coil spring 1 held by the 1 st holding mechanism 81 is fed into the 2 nd chamber 62. At the same time, the 2 nd holding mechanism 82 moves toward the 1 st chamber 61. In step S12, the 2 nd coil spring 1 is set in the 2 nd holding mechanism 82.

In step S13, the 1 st coil spring 1 in a compressed state is shot-peened while being rotated (rotated) by the rotation mechanism 100 in the 2 nd chamber 62. That is, SH2 is ejected toward the 1 st coil spring 1 by the 1 st and 2

nd ejection units

55 and 56 moving in the up-down direction. Since the shot peening is performed in a state in which stress is applied, compressive residual stress that effectively improves the durability of the coil spring 1 can be formed on the surface layer portion of the coil spring 1.

In step S14, the dial 79 rotates 180 ° in the 2 nd direction. By this rotation, the coil spring 1 held by the 1 st holding mechanism 81 is returned to the 1 st chamber 61. Further, the coil spring 1 held by the 2 nd holding mechanism 82 is fed into the 2 nd chamber 62.

In step S15, the upper support seat 81b of the 1 st holding mechanism 81 is raised. Then, the 1 st coil spring 1 held by the 1 st holding mechanism 81 is taken out by the robot 21. The 3 rd coil spring 1 is set in the empty 1 st holding mechanism 81 by the robot 21. Then, the coil spring 1 is compressed by the lowering of the upper support seat 81 b.

In step S16, the 2 nd coil spring 1 in the compressed state is shot-peened while being rotated (rotated) by the rotation mechanism 100 in the 2 nd chamber 62. That is, SH2 is ejected toward the 2 nd coil spring 1 by the 1 st and 2

nd ejection units

55 and 56 moving in the up-down direction.

In step S17, the dial 79 is rotated again by 180 ° in the 1 st direction. By this rotation, the 2 nd holding mechanism 82 is returned to the 1 st chamber 61 while returning the coil spring 1 held by the 1 st holding mechanism 81 to the 2 nd chamber 62. The upper support seat 82b of the 2 nd holding mechanism 82 is raised. Then, the coil spring 1 held by the 2 nd holding mechanism 82 is taken out by the robot 21. The next coil spring 1 is set in the empty 2 nd holding mechanism 82 by the robot 21. Then, the coil spring 1 is compressed by the lowering of the upper support seat 82 b. The series of steps S10 to S17 are repeated in accordance with the number (N) of coil springs 1, and shot peening of all the coil springs 1 is completed.

Fig. 11 is a schematic diagram showing an example of the temporal change (relationship between time and load) of the load generated at the time of shot peening by the shot peening device 50 in a certain temperature range. For example, when the coil spring 1 held by the 1 st holding mechanism 81 is shot peening-strengthened in a certain temperature range by the shot peening device 50, the coil spring 1 is gradually compressed by the pressing mechanism 93. Since the interval from t0 to t1 is a non-inductive band of the load sensor 96, the load is not detected. However, when the load exceeds the non-inductive band, the coil spring 1 is further compressed, and the load detected by the load sensor 96 increases from Z1 to Z2. At time t2, once the target load Z2 is reached, the pressurizing mechanism 93 is stopped. Then, while the compression amount (compression stroke) of the coil spring 1 is kept constant, shot peening is performed in a constant temperature range from time t3 (shot peening SH 2). The shot peening performed in the predetermined temperature range is performed until time t 4.

When compressive residual stress is generated in the coil spring 1 by shot peening strengthening in a certain interval, the load tends to slightly increase due to the influence of the compressive residual stress, as shown by the one-dot chain line m1 in fig. 11. However, in this temperature range, the function of the compressed coil spring 1 deteriorates, and therefore, as indicated by the broken line m2, the load is significantly reduced. Therefore, the total load, as shown by the solid line m3, tends to be slightly reduced. The total load (solid line m3) is determined by taking into account both the increase in load due to the generation of compressive residual stress (solid line m1) and the decrease in load due to "functional deterioration" in the coil spring 1 (solid line m 2). Therefore, the total load (solid line m3) may also be increased.

In the shot peening apparatus 50 of the present embodiment, the load detected by the

load sensors

96 and 97 during shot peening strengthening in a certain temperature range is continuously monitored by the control unit. Then, information on the detected load is displayed on the display unit 112. While storing the information in the memory or storage medium 114 of the information processing device 110. The information (such as a change in load with time) stored in the storage medium 114 can be taken out as needed. When the detected load variation is within the allowable range, it is determined that the shot peening strengthening within the accurate certain temperature range is performed in a state where a predetermined load is applied to the coil spring.

As described above, while the shot peening apparatus 50 performs shot peening during a certain temperature range, data relating to temporal changes in load is stored in advance in the internal memory or storage medium 114 of the information processing apparatus 110. By the above operation, it is possible to ensure that the shot peening strengthening in a certain temperature range is correctly applied to the coil spring, that is, the quality can be ensured.

The "functional deterioration" of the coil spring generated during shot peening may become a problem. In this case, as shown by a two-dot chain line m4 in fig. 11, signals output from the

load sensors

96 and 97 are fed back to the pressurizing mechanism 93 so that the load becomes constant during shot peening in a constant temperature zone. Then, shot peening strengthening in a certain temperature interval is performed under a substantially constant compression load by driving the pressurizing

units

94, 95 in real time and changing the compression stroke.

Fig. 12 is a schematic view showing another example of a change with time in a load generated in shot peening in a certain temperature range. As shown by a solid line m5 in fig. 12, there is a case where the load suddenly decreases beyond the allowable range (threshold) at time t 5. In this case, the coil spring in shot peening may be disengaged from the 1 st holding mechanism 81 or the 2 nd holding mechanism 82. Therefore, when such a sudden load drop is confirmed, it is determined that shot peening strengthening within a certain temperature range is not correctly performed, and the coil spring is treated as a defective product.

As shown by a broken line m6 in fig. 12, when the load during shot peening changes periodically, it is considered that the coil spring 1 is held in an unstable state. Therefore, even when the load change is confirmed as described above, it is determined that the shot peening strengthening within the certain temperature range is not correctly performed, and the coil spring is treated as a defective product.

Industrial applicability

In carrying out the present invention, it goes without saying that the form, structure, arrangement, and the like of each element constituting the shot peening apparatus may be modified and implemented. For example, as the control unit for processing the signal output from the load sensor, a personal computer may be used, or an information processing device storing a computer program developed specifically for use in the shot peening device may be used. Further, a load detector other than the load sensor may be used.

Claims

1. A shot peening apparatus is provided with: a turntable mechanism (52), wherein the turntable mechanism (52) comprises a turntable (79) which takes a revolution axis (X1) as a center;

a revolution mechanism (80), the revolution mechanism (80) being used for rotating the turntable mechanism (52);

a holding mechanism (81, 82) for holding the lower support ring (1 a) and the upper support ring (1 b) of the coil spring (1) in a posture in which the coil spring (1) is erected, and moving together with the turntable (79) about the revolution axis (X1);

a rotation mechanism (100) for rotating the holding mechanisms (81, 82) about rotation axes (X2, X3) by the rotation mechanism (100);

a pressing mechanism (93), the pressing mechanism (93) being for compressing the coil spring (1) when the coil spring (1) is held in the state of the holding mechanism (81, 82);

a load detector for detecting a load applied to the coil spring (1) by the pressurizing mechanism (93);

-an injection mechanism (57), said injection mechanism (57) being adapted to inject a steel shot on said compressed coil spring (1);

a control section (98), the control section (98) detecting a change in the load based on an output signal of the load detector;

the control unit (98) has a device for storing the change in the load with time.

2. A shot peening apparatus according to claim 1, wherein the load detector is a load sensor disposed on a load transmission path between the pressing mechanism (93) and the holding mechanisms (81, 82).

3. A shot peening apparatus according to claim 1, wherein the control unit (98) has a display unit (112) that displays a change in the load with time.

4. A shot peening apparatus according to claim 2, wherein the control unit (98) has a display unit (112) that displays a change in the load with time.

5. A shot-peening apparatus according to claim 1 or 2, wherein the control unit (98) is provided with a device that notifies when the load exceeds an allowable range while the shot mechanism (57) is shooting the steel shot on the coil spring (1).

6. A shot-peening apparatus according to claim 1 or 2, wherein the control unit (98) controls the operation of the pressurizing mechanism (93) so that the load approaches a predetermined value while the shot mechanism (57) shots the coil spring (1).