JPH09193015A - Shot peening device and shot peening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent roughness of a surface while sufficiently securing strength of a processing object without performing two-stage shots incurring a cost increase and reduction in the working efficiency. SOLUTION: Shot ball guide passages 35 to downward guide shot balls 7 projected toward a gear 1 from a projecting nozzle 5 by its dead weight, are arranged in a plurality so as to become the multistage constitution. The respective shot ball guide passages 35 are provided with sifting nets 43a to 43d which sift out the shot balls 7 less than a prescribed grain diameter to the upstream end of a lower stage side shot ball guide passage and whose mesh size in the lower stage shot ball guide passage is formed smaller than an upper stage one and load sensors 45a to 45d to detect weight of the shot balls. An average grain diameter of the shot balls supplied to the projecting nozzle 5 by flowing out from the lower end of the lowest stage shot ball guide passage 35d, is calculated by a controller 47 on the basis of weight of the shot balls detected by the load sensors 45a to 45d, and when the average grain diameter is less than an allowable average grain diameter, a new ball inflow gate 41 is opened, and new balls are inputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a projection nozzle for projecting a shot ball toward an object to be processed, and a used shot ball projected from the projection nozzle toward the object to be processed is repeatedly used. The present invention relates to a shot peening apparatus and a shot peening method configured to supply to a projection nozzle.

[0002]

2. Description of the Related Art Shot peening, which is known as a technique for projecting a shot ball made of steel balls or the like onto an object to be treated to improve its fatigue strength, is performed on a gear used in, for example, a speed reducer of an automobile. Be seen. FIG. 7 shows a shot peening apparatus for performing shot peening on the carburized gear 1.

A gear 1 which is an object to be processed is set in a shot chamber 3, and a shot ball 7 is projected toward the gear 1 from a projection nozzle 5. A mixing gate 11 is provided on the upstream side of the pipe 9 connected to the projection nozzle 5,
In the mixing gate 11, the shot ball 7 supplied from the hopper 13 via the pressure tank 15 is blown with pressurized air adjusted by an air regulator 17 provided on the upstream side of the mixing gate 11.

On the other hand, a shot ball receiver 19 is installed below the shot chamber 3, and used shot balls projected from the projection nozzle 5 to the gear 1 are shot ball receiver 19 from the discharge port 3a below the shot chamber 3. Is discharged inside. The shot ball receiver 19 is provided with a screw conveyor 21 extending upward, and the shot balls in the shot ball receiver 19 are conveyed to the separator chamber 23 at the upper end.

The separator chamber 23 is arranged above the hopper 13, and a shot ball guide passage 25 for guiding the shot balls in the separator chamber 23 to the hopper 13 by its own weight is provided between them. A sieving net 27 is provided in the shot ball guiding passage 25, and shot balls having a particle size larger than the mesh size of the sieving net 27 are guided to the hopper 13 to repeatedly use the used shot balls.

Below the sieving net 27, a shot ball discharge duct 29 is installed. Each time the shot balls are repeatedly projected onto the gear 1, the shot balls become smaller due to cracking and wear, and when the particle size becomes smaller than the mesh size of the sieving net 27, the shot balls are sifted off to the shot ball discharge duct 29 and are discarded to the outside. Will be rejected. Further, a dust collector (not shown) is connected to the separator chamber 23 and the shot chamber 3 via the pipes 31 and 33, and the fragments of the shot balls, which have become small due to the above-mentioned cracks and wear, are discarded outside by the dust collector. .

On the other hand, a ball shortage warning sensor 34 is installed on the side of the hopper 13, and when the total amount of shot balls is insufficient, the ball shortage warning sensor 34 outputs a warning sound and responds to this. An operator supplies a new shot ball to the hopper 13.

[0008]

By the way, in the above shot peening process, if the particle size of the shot balls is different, the influence on the gear, which is the object to be processed, changes. For example, small diameter (φ0.3mm-φ0.6mm)
While the shot balls of No. 1 have the advantage of preventing the tooth surface from becoming rough, there are many unclear parts in terms of strength. Conversely, shot balls of large diameter (about φ1.0 mm to φ1.2 mm) have sufficient strength. While it is obtained, the roughness of the tooth surface shape occurs,
Conflicting results are obtained. Therefore, in order to secure the sufficient strength and prevent the tooth surface from being roughened, for example, Japanese Patent Laid-Open No. 2-1
As described in Japanese Patent No. 85370, first, a shot ball having a large diameter is projected to secure strength, and then a shot ball having a small diameter is projected to prevent roughness of a tooth surface shape, that is, a so-called two-stage shot. There is a way to do.

However, in the method of performing the two-stage shot, a shot peening device is installed corresponding to each of the two types of shot balls, or a large-diameter shot ball is projected by one device and then shot. It is necessary to replace the sieving net to correspond to the particle size of the balls and at the same time to replace the large-diameter shot balls with the small-diameter shot balls.These methods lead to higher costs and lower work efficiency. Becomes

Therefore, an object of the present invention is to prevent the surface from being roughened while ensuring the strength of the object to be treated without inviting a high cost and a decrease in working efficiency.

[0011]

In order to achieve the above object, the present invention firstly comprises a projection nozzle for projecting a shot ball toward an object to be processed, and the projection nozzle directs the object toward the object to be processed. In the shot peening apparatus configured to supply the used shot balls projected by the projection nozzle to be repeatedly used, an inclined shot ball guide passage for guiding the shot balls downward by their own weight,
A plurality of balls are provided in a multi-stage configuration, shot balls having a particle size smaller than a predetermined particle size are sifted into each shot ball guide passage, and the one in the shot ball guide passage on the lower side has a smaller mesh size than the one on the upper side. A selection means and a weight detection means for detecting the weight of a shot ball having a predetermined particle size or more which is guided downward through the ball selection means are respectively provided, and the upstream end of the shot ball guide passage on the lower side is the upper side. Connected to the lower side of the ball selection means, the downstream end of the upper shot ball guide passage is connected to the downstream side of the lower weight detection means, to the weight of the shot ball detected by each weight detection means. Based on the configuration, an average particle size calculating means for calculating the average particle size of the shot balls flowing out from the downstream end of the shot ball guide passage at the lowermost stage and supplied to the projection nozzle is provided. Are you.

Secondly, in the first construction, a shot ball inlet for inserting a new shot ball and provided with an opening / closing means is provided at the upstream end of the uppermost shot ball guide passage, and the average particle diameter calculating means is provided. When the average particle size calculated in step 1 is smaller than the allowable average particle size set in advance corresponding to the predetermined projection speed of the shot balls projected from the projection nozzle, the opening / closing means is opened to open a new product. A configuration is provided in which a control unit that causes shot balls to enter the shot ball guide passage is provided.

Thirdly, in the first construction, the average particle size calculated by the average particle size calculating means is set in advance in correspondence with the predetermined projection speed of the shot ball projected from the projection nozzle. When it becomes smaller than the average particle diameter, the projection speed of the shot balls projected from the projection nozzle is increased.

Fourthly, in a shot peening method in which used shot balls projected from the projection nozzle toward the object to be processed are repeatedly supplied to the projection nozzle, the shot peening method is supplied to the projection nozzle. The average particle size of the shot balls is calculated, and when this average particle size becomes smaller than the allowable average particle size corresponding to the predetermined projection speed of the shot balls projected from the projection nozzle, a new shot ball is projected. This is a method of supplying to the nozzle.

[0015]

According to the first invention or the fourth invention,
The permissible average particle diameter corresponding to the predetermined projection speed of the shot balls projected from the projection nozzle is determined in advance, and when the calculated average particle diameter of the shot balls becomes smaller than this permissible average particle diameter, By supplying the shot ball of No. 1 to the shot ball guide passage, the shot ball supplied to the projection nozzle has an average particle size larger than the allowable average particle size, and as a result, the prescribed shot peening process can be continuously performed.
Since such shot peening can be performed with shot balls with a small diameter, it is possible to secure the strength of the object to be processed while avoiding the roughness of the surface of the object to be processed. The so-called two-stage shot is not necessary, and only the small-diameter ball is required for the one-stage shot, so that the cost can be reduced and the working efficiency can be improved.

According to the second aspect of the present invention, the average particle size calculated by the average particle size calculating means is set in advance in correspondence with the predetermined projection speed of the shot ball projected from the projection nozzle. When the diameter becomes smaller than the diameter, the opening / closing means is opened and a new shot ball is thrown into the shot ball guide passage. Therefore, in addition to the effect of the first invention, the operator manually supplies a new shot ball. The workability can be improved because it is not necessary to perform.

According to the third aspect of the invention, in addition to the effect of the first aspect of the invention, when the average grain size of the shot balls falls below the allowable average grain size, the projection speed of the shot balls is increased, so that a new product can be obtained. The allowable average particle diameter is reduced without adding the shot balls, and the consumption of the shot balls can be reduced.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a shot peening apparatus showing an embodiment of the present invention. In the above embodiment, the same components as those of the conventional device shown in FIG. 7 are designated by the same reference numerals. This shot peening apparatus can use small-diameter shot balls having a particle size of φ0.3 mm to φ0.6 mm (here, shot balls of φ0.5 mm are used), and the hopper 13 and the separator chamber 23 are An inclined shot ball guide passage 35 which is disposed between the two and guides the shot ball downward by its own weight.
(First guide passage 35a, second guide passage 35b, third
The plurality of guide passages 35c and the fourth guide passages 35d are provided (here, four stages) so as to have a multi-stage configuration.

The upstream end of the uppermost first guide passage 35a communicates with the separator chamber 23, and the downstream end 35d ₁ of the lowermost fourth guide passage 35d communicates with the hopper 23.
A new ball 37 for storing new shot balls is connected near the upstream end of the first guide passage 35a through a communication pipe 39 that constitutes a shot ball input port.
9 is provided with a new ball inflow gate 41 as an opening / closing means.

In each of the above-mentioned four shot ball guide passages 35, sieving nets 43a, 43b, 43c serving as ball selecting means for sieving shot balls having a particle diameter smaller than a predetermined particle size to the upstream end of the lower shot ball guide passage. 43d and a weight which is located on the downstream side of the sieving nets 43a, 43b, 43c, 43d and which detects the weight of a shot ball having a predetermined particle size or more that is guided downward through the sieving nets 43a, 43b, 43c, 43d. Load cells 45a, 45 as detecting means
b, 45c and 45d are installed respectively.

The first, second and third guide passages 35
a, 35b, 35c downstream ends 35a ₁ , 35b ₁ , 35
c ₁ is each of the guide passages 35b, 35c, 3 below
The load cells 45b, 45c, and 45d in 5d communicate with the downstream side.

Sieve nets 43a, 43b, 43c, 43d
Has a larger mesh size in the upper shot ball guide passage than in the lower shot ball guide passage. Specifically, it is only necessary to select four kinds from the diameter of 0.2 mm to 0.6 mm, and since the particle diameter of the shot balls is 0.5 mm here, the sieve mesh 43a having the largest mesh size.
Is 0.500 mm, and the following is sieve screen 43b is 0.425 m
m, sieving net 43c is 0.355 mm, sieving net 43d
Is 0.300 mm. The shot ball discharge duct 2 is provided in the sieving net 43d of the lowermost fourth guide passage 35d.
9 is connected and the shot balls which have been sieved off by the sieving net 43d are discarded to the outside.

On the other hand, the load cells 45a, 45b, 45
c and 45d detect the number of shot balls having a particle size equal to or larger than each particle size passing during a fixed time, and this detection signal is input to a controller 47 as a control means. Controller 47
Calculates the weights W ₁ , W ₂ , W ₃ , W ₄ of shot balls, respectively, based on the number of shot balls having a particle size or more detected by the load cells 45a, 45b, 45c, 45d,
The average particle diameter D of the shot balls flowing out from the lowermost fourth guide passage 35d to the hopper 13 is calculated by the following equation. That is, the controller 47 controls the lowermost fourth guide passage 3
The average particle diameter calculating means for calculating the average particle diameter of the shot balls flowing out from the downstream end 35d _{1 of} 5d and supplied to the projection nozzle 5 is included.

D = 0.5 W ₁ /ΣW+0.425 W ₂ / ΣW +
0.355 W ₃ /ΣW+0.3 W ₄ / ΣW However, ΣW = W ₁ + W ₂ + W ₃ + W ₄ By the way, when performing the shot peening process on the gear 1 which is the object to be processed, the strength of the gear 1 is sufficient and In order to prevent the tooth surface from becoming rough, as shown in FIG. 2, the relationship between the average particle diameter D (mm) of the shot ball and the projection speed V (m / s) of the shot ball projected from the projection nozzle 5 is: It needs to be within a region B shown by a diagonal line on the right side of the line segment A. That is, for example, when the projection speed V is 80 m / s, the allowable average particle size D _S of the shot balls is φ0.4 mm or more, and the controller 47 calculates that the calculated average particle size D of the shot balls is the allowable average particle size. When it is determined that the diameter is smaller than the diameter D _S , a signal is output to open the new ball inflow gate 41.

A shot ball 7 projected from the projection nozzle 5.
The projection speed V of can be changed by adjusting the mixing gate 11 and the air regulator 17,
The changed projection speed V is measured by the speed measuring machine 49 and input to the controller 47. Controller 47
Then, the allowable average particle diameter D _S in FIG. 2 corresponding to the inputted speed signal is set. Furthermore, the detection signal of the ball shortage warning sensor 34 arranged on the side of the hopper 13 is input to the controller 47, and the controller 4
Reference numeral 7 informs the worker of a warning of shortage of balls, for example, by displaying a display (not shown) or outputting a warning sound using a speaker, and the worker supplies a new shot ball to the hopper 13 based on this.

In the above shot peening apparatus, the shot balls 7 projected on the gear 1 are conveyed to the separator chamber 23 by the screw conveyor 21 and then fed into the first guide passage 35a at the uppermost stage to guide each ball. Passage 35
a, 35b, 35c, 35d, the respective sieve nets 43a,
Shot balls with a smaller diameter than the mesh size of 43b, 43c, 43d are sieve nets 43a, 43b, 43c, 43d.
On the other hand, the shot balls having a particle size not less than each of the mesh sizes are sieved off by the sieving nets 43a, 43b, 4
Load cells 45a, 45b, 4 passing through 3c, 43d
5c and 45d are reached, and the number of shot balls having each particle size or more within a fixed time is detected.

Each signal value of the detected number of shot balls is input to the controller 47, and the controller 47 is operated as shown in FIG.
As shown in the flowchart of FIG. ₅ , the weights W ₁ , W ₂ , W ₃ , and W ₄ of shot balls having respective particle sizes or more are calculated (step 301). This weight calculation is performed by previously measuring the weight of each shot ball having a particle size or more and multiplying the weight per shot by the number of shot balls of each particle size detected above. After the weight is calculated, the downstream end 3 of the lowermost fourth guide passage 35d is calculated based on the above equation.
The average particle diameter D of the shot balls flowing out from 5d ₁ to the hopper 13 is calculated (step 303).

Next, the calculated average particle diameter D and the allowable average particle diameter D when the shot speed of the shot ball is V ₁ (m / s)
_S1 is compared (step 305), and when D is less than D _S1 , the new ball inflow gate 41 is opened and the new ball tank 37 is opened.
The new shot ball in the first guide passage 35a at the top
(Step 307). This allows the hopper 1
When the average particle diameter D of the shot balls flowing out to No. 3 becomes large and the average particle diameter D becomes equal to or more than the allowable average particle diameter D _S1 ,
The projection state in the area B in FIG. 2 is maintained, the strength of the gear 1 is sufficiently secured by the shot peening process, and at the same time, the roughness of the tooth surface shape is avoided.

FIG. 4 shows the particle size distribution of shot balls as the residual rate [Wt (weight)%] of the shot balls in each of the sieving nets 43a, 43b, 43c, 43d. FIG. 7A shows a case where there are no used shot balls and all are new shot balls (particle diameter 0.5 mm). In the same figure (b), the shot peening process is performed from the state of (a), and the shot balls are worn and the number of shot balls having a particle size of 0.5 mm decreases.
mm and each 0.425 mm shot ball increase,
The average particle size D is reduced to 0.42 mm and the allowable average particle size D
_This is the case when the value is below _S1 (here, 0.45 mm). In the same figure (c), the new ball inflow gate 41 is opened from the state of (b) and a new ball is thrown in, the proportion of new shot balls having a particle diameter of 0.5 mm is increased, and the average particle diameter D is 0. 46 mm
Is the case where the allowable average particle size exceeds 0.45 mm.

According to the above shot peening apparatus, the calculated average particle diameter D of shot balls is the allowable average particle diameter D.
When the average particle diameter D exceeds the permissible average particle diameter D _S1 by introducing a new shot ball from the new ball tank 37 into the uppermost first guide passage 35a when the value falls below _S1. Peening processing can be continued. For this reason,
It is not necessary to perform a so-called two-stage shot in which a shot ball having a large diameter is used and then a shot ball having a small diameter is used, and the strength of the gear 1 which is the object to be processed is sufficiently secured, and φ0.3 mm to 0 Since a shot ball with a small diameter of 6 mm can be used, it is described on pages 4 to 6 of Ark Height ["Shot Peening Work Standard" (published by the Japan Spring Manufacturers Association on September 1, 1982). Thus, what is represented as the warp amount of the test plate when shot peening is applied to the test plate of a certain size (almen strip)] is lowered, and it is possible to prevent the tooth surface from being roughened.
In addition, it is possible to prevent wear of the device itself.

FIG. 5 shows step 305 in FIG.
When it is determined that the average particle diameter D is below the allowable average particle diameter D _S1 when the projection speed V is V ₁ (m / s), the average particle diameter D is not changed, that is, a new ball is introduced. Without adjusting the air regulator 17 and the mixing gate 11, the projection speed V of the shot ball projected from the projection nozzle 5
Is increased from V ₁ to V ₂ as shown in FIG. Although the operator may manually prepare the air regulator 17 and the mixing gate 11,
It may be possible to automatically prepare by the controller 47.

The blasting speed V is measured by the speed measuring device 49, desired at the time when the speed V ₂ is measured, the controller 47 is allowed average particle diameter D _S of the D _S1 D _S1 is smaller than D _S2
(Step 501). As a result, the average particle size D
However, it is possible to exceed the reduced allowable average particle diameter D _S2 , and the gear 1 has sufficient strength and is capable of continuously performing the prescribed shot peening processing without causing tooth surface roughness. Become.

In this case, by increasing the projection speed V, the prescribed shot peening process can be continuously performed without the need to insert a new shot ball, so that the consumption amount of the shot ball 7 can be reduced. It is possible to reduce the cost.

After that, when the shot peening process is continued and the average particle size D is below the allowable average particle size D _S2 (step 503), the new ball inflow gate 41 is operated in the same manner as the operation shown in FIG. Open the new ball tank 37
The new shot ball in the first guide passage 35a at the top
(Step 505). This allows the hopper 1
The average particle diameter D of the shot balls flowing out to No. 3 is made equal to or _larger than the changed allowable average particle diameter D _S2 .

In the above embodiment, when the average particle diameter D is below the allowable average particle diameter D _S1 or D _S2 , the controller 47 opens the new ball inflow gate 41 to insert a new ball. However, the controller 47 may display the above result on a display or the like, and the operator may manually watch and insert the new ball into the first guide passage 35a.

The load cell 4 serving as a weight detecting means
Although 5a, 45b, 45c, 45d detect the number of shot balls having a particle size or more within a fixed time, the shot balls are closed on these load cells 45a, 45b, 45c, 45d for a fixed time. To stop, load cells 45a, 45
A pair of shutter plates, for example, are provided on the upstream side and the downstream side of b, 45c, 45d, respectively, in the guide passages 35a, 35b, 35.
Alternatively, the weight of the shot ball blocked between the pair of shutter plates may be measured so that it can project from the bottom surface of the c and 35d.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a shot peening apparatus showing an embodiment of the present invention.

FIG. 2 is a correlation diagram between the average particle diameter of shot balls and the projection speed.

FIG. 3 is a flowchart showing an operation of the shot peening apparatus of FIG.

FIG. 4 is an explanatory view showing a particle size distribution of shot balls as a residual rate of shot balls in four sieving nets, (a) is a new shot ball, (b) is a worn shot ball, and (c) is a shot ball.
Is for replenishing new shot balls.

5 is a flowchart showing another operation of the shot peening apparatus of FIG.

FIG. 6 is an explanatory diagram showing the correlation between the average particle size of shot balls and the projection speed in the operation of FIG.

FIG. 7 is an overall configuration diagram of a shot peening apparatus showing a conventional example.

[Explanation of symbols]

1 Gear (Processing Object) 5 Projection Nozzle 7 Shot Ball 35 Shot Ball Guide Passage 35a First Guide Passage 35b Second Guide Passage 35c Third Guide Passage 35d Fourth Guide Passage 35a ₁ , 35b ₁ , 35c ₁ , 35d ₁ Downstream end 39 Communication pipe (shot ball input port) 41 New ball inflow gate (opening / closing means) 43a, 43b, 43c, 43d Sieve net (ball selection means) 45a, 45b, 45c, 45d Load cell (weight detection means) 47 controller (control means, average particle size calculation means)

Claims (4)

[Claims] 1. A projection nozzle for projecting shot balls toward an object to be processed, and used shot balls projected from the projection nozzle toward the object to be processed are supplied to the projection nozzle for repeated use. In the shot peening apparatus configured as described above, a plurality of inclined shot ball guide passages for guiding the shot balls downward by their own weight are provided so as to have a multi-stage configuration, and each of the shot ball guide passages has a shot ball smaller than a predetermined particle diameter. And a ball selection means in which the one in the lower shot ball guide passage has a smaller mesh size than that in the upper one, and a shot having a predetermined particle size or more that is guided downward through this ball selection means Weight detection means for detecting the weight of the balls are provided respectively, and the upstream end of the shot ball guide passage on the lower side contacts below the ball selection means on the upper side. The lower end of the shot ball guide passage on the upper stage side is connected to the downstream side of the weight detecting means on the lower stage side, based on the weight of the shot balls detected by the weight detecting means. A shot peening apparatus comprising: an average particle size calculating means for calculating an average particle size of shot balls flowing out from a downstream end of a ball guide passage and supplied to the projection nozzle. 2. A shot ball charging port for charging a new shot ball and having an opening / closing means is provided at the upstream end of the uppermost shot ball guiding passage, and the average particle diameter calculated by the average particle diameter calculating means is , When the particle size becomes smaller than the permissible average particle size set in advance corresponding to the predetermined projection speed of the shot balls projected from the projection nozzle, the opening / closing means is opened to insert a new shot ball into the shot ball guide passage. The shot peening apparatus according to claim 1, further comprising a control means for charging. 3. When the average particle diameter calculated by the average particle diameter calculating means becomes smaller than an allowable average particle diameter set in advance corresponding to a predetermined projection speed of a shot ball projected from a projection nozzle. The shot peening apparatus according to claim 1, wherein a projection speed of a shot ball projected from the projection nozzle is increased. 4. A shot ball supplied to the projection nozzle in a shot peening method in which a used shot ball projected from a projection nozzle toward an object to be processed is supplied to the projection nozzle for repeated use. When the average particle size is smaller than the permissible average particle size corresponding to the predetermined projection speed of the shot ball projected from the projection nozzle, a new shot ball is projected onto the projection nozzle. A shot peening method characterized by supplying.