JP2013086225A - Shot blasting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shot blasting machine capable of uniformly grinding and cleaning the entire inner surface of a steel pipe having an uneven shape when the inner surface is subjected to grinding and cleaning processing.SOLUTION: There is provided the shot blasting machine that grinds and cleans the inner surface of the steel pipe having the uneven shape by inserting a nozzle 1 into the steel pipe and jetting grinding and cleaning materials from heads 1a, 1b that the nozzle 1 has while rotating the steel pipe, the nozzle 1 including the first head 1a jetting the grinding and cleaning material in a direction forming an acute angle to the nozzle insertion direction on a steel pipe axis and the second head 1b jetting the grinding and cleaning material in a direction forming an obtuse angle.

Description

  The present invention relates to a shot blasting apparatus, and more particularly to a shot blasting apparatus suitable for blasting of a steel pipe having an uneven surface on the inner surface.

  For the purpose of surface treatment such as painting, thermal spraying, scale removal, or surface roughness adjustment, a surface of the steel material is subjected to a polishing process using a shot blasting apparatus. When performing the blasting process using the shot blasting apparatus on the inner surface of the steel pipe, the following two methods are roughly used.

  One is to perform a scouring process by inserting a nozzle smaller than the inner diameter of the steel pipe, which is the object to be polished, into the steel pipe and injecting the scouring material from the nozzle head using compressed air. The other is that, by using a pipe passage through which the blast material passes through the inner surface of the steel pipe without using a nozzle, the blast material collides so as to slide on the inner surface of the steel pipe to perform the blasting process.

  Patent Document 1 discloses a shot blasting apparatus capable of inserting a nozzle into each of a plurality of steel pipes and simultaneously polishing the inner surface of the pipe. Further, Patent Document 2 discloses a scouring apparatus that aspirates air from one end of a steel pipe and scours the inner surface of the pipe by passing a scouring material through the steel pipe.

JP 61-82924 JP 63-22271

  The shot blasting apparatus of the system described in Patent Documents 1 and 2 is effective for the polishing treatment of a steel pipe having a smooth inner surface. However, when performing a blasting process on a steel pipe having an uneven surface on its inner surface, in the conventional shot blasting apparatus, as shown in FIG. 1, the scouring material 30 injected from the nozzle 1 collides with the bottom surface or side surface of the recess. However, there is a problem that an abrasive collision impossibility region (see symbol A in the figure) occurs.

  Examples of the steel pipe having an uneven shape on the inner surface include an internal thread portion of an oil well pipe. In recent years, use of oil well pipes in highly corrosive environments has been demanded, and accordingly, high alloy steels having excellent corrosion resistance have been used for oil well pipes. High alloy steel is inferior in seizure resistance compared to low alloy steel or carbon steel conventionally used in oil well pipes.

  Lubricating oil is used as a lubricating sealant when steel pipes are fastened with male and female threads at the end of the pipe. The oil retention was improved. Further, as a further measure for preventing seizure, it is required to perform a cleaning process on the female thread portion in addition to the male thread portion.

  However, as described above, when the blasting process of the female thread portion is performed, if a scouring material collision-impossible region occurs, the scouring process in that region becomes insufficient, and a sufficient improvement in oil retention cannot be expected. Arise.

  Therefore, the present invention provides a shot blasting apparatus that can evenly polish the entire surface without causing a region where the abrasive cannot collide even when the inner surface of the steel pipe having a concavo-convex shape is polished. For the purpose.

  As a result of various studies on the shot blasting apparatus suitable for the polishing treatment of the inner surface of a steel pipe having an uneven shape, the present inventors have obtained the following knowledge.

  In the method of performing the blasting treatment by using a pipe through which the scouring material passes through the inner surface of the steel pipe without using a nozzle, it is extremely difficult to uniformly scour the inner surface of the steel pipe having an uneven shape. It is necessary to adopt a system in which the nozzle is inserted into the steel pipe and the polishing process is performed by spraying the polishing material from the nozzle head. However, even when a nozzle is used, it is difficult to completely clean the bottom surface and the side surface of the concave portion as described above by injection in only one direction.

  In order not to generate the abrasive impingement impermissible region, two or more heads that can inject the abrasive in at least two directions of an acute angle and an obtuse angle with respect to the nozzle insertion direction on the steel pipe shaft are used. There is a need.

  The present invention has been completed on the basis of the above findings, and the gist thereof is a shot blasting apparatus shown in the following (1) to (5).

  (1) A shot blasting apparatus that performs a blasting process on the inner surface of a steel pipe having a concavo-convex shape by inserting a nozzle into the steel pipe and injecting a scouring material from a head provided on the nozzle while rotating the steel pipe. A first head for ejecting the abrasive in a direction in which the nozzle forms an acute angle with respect to a nozzle insertion direction on the steel pipe shaft; and a second head for ejecting the abrasive in a direction making an obtuse angle. A shot blasting device.

  (2) The shot blasting apparatus according to (1), wherein the second head is configured to be able to reach the back side of the steel pipe from the first head.

  (3) The shot blasting apparatus according to (1) or (2), wherein the blast material jetting directions of the first head and the second head are different in the circumferential direction.

  (4) The shot blasting apparatus according to any one of (1) to (3), wherein the abrasive is sucked and collected from the end of the tube on the side where the nozzle is inserted.

  (5) The shot blasting apparatus according to (4) above, further comprising an inner plug for suppressing the diffusion of the abrasive from the nozzle to the back side of the steel pipe.

  (6) The shot blasting apparatus according to (5) above, further comprising an air blow nozzle for discharging the abrasive remaining in the steel pipe from the inner plug to the back side of the steel pipe.

  According to the present invention, in the blasting process of the inner surface of the steel pipe having the concavo-convex shape, the non-abrasive material collision-impossible region does not occur, so that the inner surface of the steel pipe can be uniformly scoured. Therefore, the shot blasting apparatus of the present invention is optimal when performing a polishing process on a steel pipe having an inner surface formed with irregularities such as screws or ribs.

It is the figure which showed typically the scouring material collision impossibility area | region which arises with the conventional shot blasting apparatus. It is the figure which showed typically an example of the shot blasting apparatus which concerns on this invention. It is a figure explaining the relationship between an ejection angle and the angle which collides with a dovetail side surface.

  FIG. 2 is a diagram schematically showing a shot blasting apparatus according to the present invention. In the shot blasting apparatus of the present invention, one or more (two in the example shown in FIG. 2) nozzles 1 are inserted into a steel pipe, and the abrasive is made from the heads 1a and 1b provided on the nozzle 1 while rotating the steel pipe. The surface of the inner surface of the steel pipe is blasted by spraying. At this time, the nozzle 1 injects the abrasive in at least two directions: an acute angle (see symbol 22a in the figure) and an obtuse angle (see symbol 22b) in the nozzle insertion direction on the steel pipe shaft. It has two or more possible heads 1a, 1b.

  In addition to the above, the shot blasting apparatus of the present invention has an internal plug 2 for restricting the diffusion of the abrasive, or an air blow nozzle 3 for discharging the abrasive remaining in the pipe. Also good. Details of each component will be described below.

1. Nozzle 1 according to the present invention includes a first head 1a capable of injecting an abrasive at least in a direction that forms an acute angle with respect to a nozzle insertion direction on a steel pipe shaft, that is, a direction that forms an obtuse angle, that is, a steel pipe. Has a second head 1b that can eject the abrasive in the forward direction. By performing the blasting process from both the front side and the back side of the steel pipe, it is possible to prevent the occurrence of the scouring material collision-impossible region even when the scouring process is performed on the inner surface of the steel pipe having an uneven shape. In the present invention, it is sufficient that at least the first head and the second head are included, and a head other than these heads may be included.

  At this time, one nozzle having two or more heads may be used, or two nozzles each having one head may be used, but the amount of the abrasive material ejected from all the heads In order to make the ejection speed uniform, it is preferable to use two nozzles having one head.

  Steel pipes to be subjected to the blasting process using the shot blasting apparatus of the present invention include those having an inner diameter of about 140 mm. Therefore, it is necessary to efficiently arrange the nozzles 1 in a limited space. Therefore, as shown in FIG. 2, it is preferable to use a configuration in which two nozzles 1 each having one first head 1a and one second head 1b are used.

  Further, in order to perform a polishing process from both the front side and the back side of the steel pipe in all regions of the scouring range, as shown in FIG. 2, the second head 1b is made of the steel pipe by the first head 1a. It is preferable to have a configuration that can reach the far side.

  In the arrangement as described above, if the portions to be cleaned of each head overlap, the polishing materials collide with each other, and sufficient cleaning processing cannot be performed at those portions. Therefore, it is desirable to shift the ejection direction of each head in the circumferential direction so that the abrasives do not interfere with each other.

  There are two types of spraying methods of the abrasive using compressed air: suction type (gravity type, siphon type) and direct pressure type (pressurization type). In the former method, the flow path of the abrasive is made negative by the flow of compressed air injected from the nozzle, and the abrasive is transported by the flow of air generated by the negative pressure and compressed in the nozzle. This is a method in which air and scouring material are mixed and sprayed, and is suitable for a wide range of scouring treatments. On the other hand, the latter method is a method in which the compressed air and the abrasive are mixed in the injector, and the abrasive is fed into the pipe and injected.

  In the shot blasting apparatus of the present invention, it is difficult to install many injection nozzles on the inner surface of the pipe. Therefore, it is preferable to use a direct pressure type having a strong force for injecting the abrasive.

  Moreover, there is no restriction | limiting in particular about the injection quantity of a scouring material, but it can set to about 5-10 kg / min per nozzle.

  The spread angle of the blast material ejected from the head (see reference numeral 21 in the figure) is appropriately selected in consideration of the fact that if it is too wide, the impact force is weakened, and if it is too narrow, uniform scouring processing becomes difficult. For example, it may be in the range of 5 to 10 °.

  There is no particular limitation on the ejection angle of the head. However, as shown in Table 1, as the injection angle increases, the average roughness Ra tends to increase, and the injection angle is 20 ° or more and becomes a substantially constant value. On the other hand, since the shot blasting apparatus of the present invention may perform a blasting process even on a groove having a dovetail shape (reverse C shape) as shown in FIG. 3, the injection angle exceeds 65 °. Then, the angle at which the abrasive material collides with the side surface of the groove becomes small, which is not preferable. Accordingly, the ejection angle of the first head 1a (see reference numeral 22a in the figure) is preferably 20 to 65 °, and more preferably 40 to 45 °. Moreover, it is preferable to set it as 115-160 degrees, and, as for the injection angle (refer code | symbol 22b in the figure) of the 2nd head 1b, it is more preferable to set it as 135-140 degrees.

2. Inner plug The sprayed abrasive is usually collected by injecting compressed air from the end of the tube where the nozzle is inserted and sucking the abrasive together with air from the other end of the tube. . However, this method results in a significant increase in installation space and cost because the collection device becomes large and the structure becomes complicated, such as the need to move the collection unit according to the length of the steel pipe. Therefore, as shown in FIG. 2, it is possible to install a scouring chamber 11 having a suction part 11a at the tube end on the side where the nozzle is inserted, and to suck and collect the sprayed scouring material. It is desirable from the viewpoint of simplifying and simplifying.

  At this time, the side opposite to the side where the nozzle is inserted is preferably sealed using the inner plug 2 so that the abrasive does not flow out. By disposing the inner plug 2, it becomes possible to limit the diffusion region of the abrasive, especially when the abrasive range is limited to a part of the steel pipe. Therefore, the abrasive can be collected very easily.

  The inner plug 2 has a hollow disk shape as shown in FIG. 2 and preferably has a structure capable of expanding and contracting by taking in and out the air therein. The material used for the inner plug 2 is not particularly limited as long as it can be expanded and contracted. For example, urethane rubber or rubber obtained by vulcanizing natural rubber at a low temperature can be used. As a result of performing repeated expansion and shrinkage durability and wear resistance tests using the above two types of rubber, no difference was found in the wear resistance against the impact of the abrasive. However, in the middle plug of urethane rubber, it is more preferable to use a rubber obtained by vulcanizing natural rubber at a low temperature because peeling may occur due to repeated expansion and contraction at a location where the adhesive is joined. Moreover, there is no restriction | limiting in particular about the diameter of the inside plug 2, What is necessary is just to select suitably according to the internal diameter of the steel pipe which performs a blasting process.

  It is preferable that the inner plug 2 is inflated by sending compressed air after being inserted to a position corresponding to the erasing range in the steel pipe, and is brought into close contact with the inner surface of the steel pipe. Further, in order not to cause wear due to friction with the steel pipe, it is preferable to be able to rotate in synchronization with the rotation of the steel pipe. That is, the shaft portion 2a that supports the inner plug can carry the inner plug to the depth of the steel pipe and feed compressed air into the inner plug, and at the same time, the disk portion 2b of the inner plug can rotate on the shaft. It is desirable to have a simple mechanism. After completion of the polishing process, the inner plug 2 is brought into a contracted state and pulled out from the steel pipe.

3. Air Blow Nozzle As shown in FIG. 2, the shot blasting apparatus according to the present invention preferably has an air blow nozzle 3 on the back side of the inner plug 2 in the steel pipe. After the polishing process is completed, the air blow nozzle 3 is inserted into the depth of the steel pipe after the inner plug is pulled out or simultaneously, and jets compressed air toward the front side of the steel pipe, so that the abrasive material remaining in the steel pipe is polished. The scavenging chamber 11 can be discharged. The air blow nozzle 3 is preferably installed on the same axis as the inner plug 2.

4). Others A shot blasting apparatus for the purpose of blasting the inner surface of a steel pipe according to the present invention is a modification of a conventional shot blasting apparatus for the outer surface of a steel pipe, and the blasting process for both the male thread part and the female thread part of the steel pipe is performed in the same apparatus. It is possible to have a configuration that can be performed. First, with respect to the male threaded portion at one end of the tube, the outer surface is cleaned using the outer surface nozzle 12 shown in FIG. Thereafter, the nozzle 1 is inserted into the female threaded portion at the other end of the tube, and the inner surface is subjected to a polishing process. At this time, depending on the outer diameter and wall thickness of the steel pipe, it is necessary to replace the seal portion 13 manually. However, it is possible to automatically and continuously perform the cleaning process of the male screw and the female screw. Processing time is within 3 minutes.

  The configuration of the outer nozzle 12 is not particularly limited. However, since a large number of nozzles can be installed, for example, the above-described suction-type injection method includes, for example, the nozzle 12 having an injection amount of 1.5 kg / min in the upper portion of the blast chamber 11. 12 can be deployed. By adopting such a configuration, even when the screw shapes are different, it is possible to arbitrarily adjust the spray angle at which uniform cleaning is possible, which is preferable. Further, it is desirable that the outer nozzle 12 has a function of automatically adjusting the height according to the outer diameter of the steel pipe and a function of automatically moving according to the length of the screw portion. Further, the cleaning chamber 11 itself preferably has a function of automatically adjusting the height according to the outer diameter of the steel pipe.

  It is preferable that the scouring material sprayed from the nozzle has a mechanism to be sucked from the suction part 11a below the scouring chamber 11 after colliding with the screw part. In this case, after the aspirated abrasive is sorted by a cyclone separator, the powdered material is sent to a dust collector and captured, and the one having a large particle size is sent to an outer surface supply tank and reused.

  Since a gap is generated between the steel pipe and the cleaning chamber, it is preferable to provide a rubber seal 13 and make the opening as small as possible. By doing so, the control wind speed of the seal part by suction can be ensured, and the sprayed abrasive can be prevented from flowing out of the abrasive chamber. Moreover, in order to prevent the abrasive from flowing into the steel pipe, it is preferable to attach an inner plug corresponding to the inner diameter of the steel pipe to the end face of the steel pipe. The inner plug may be manually attached before the outer surface cleaning process, or the inner plug used for the inner surface cleaning process may be automatically mounted.

  As described above, the structure shown in FIG. 2 has been described in detail, but the shot blasting apparatus according to the present invention is not limited to this.

  According to the present invention, in the blasting process of the inner surface of the steel pipe having the concavo-convex shape, the non-abrasive material collision-impossible region does not occur, so that the inner surface of the steel pipe can be uniformly scoured. Therefore, the shot blasting apparatus of the present invention is optimal when performing a polishing process on a steel pipe having an inner surface formed with irregularities such as screws or ribs.

1. Nozzle 1a. First head 1b. Second head 2. Inner plug 2a. Shaft 2b. Disc part 3. Air blow nozzle 11. Cleaning room 11a. Suction unit 12. External nozzle 13. Seal part 21. Spreading angle 22a. Head ejection angle 22b. With respect to nozzle insertion direction on steel pipe shaft. 30. Injection angle of head with respect to nozzle insertion direction on steel pipe shaft Abrasives A. Abrasive material collision-impossible area

Claims (6)

  A shot blasting apparatus for performing a blasting treatment on the inner surface of a steel pipe having an uneven shape by inserting a nozzle into the steel pipe and spraying a blast material from a head provided on the nozzle while rotating the steel pipe, The nozzle includes a first head that ejects the abrasive in a direction that forms an acute angle with respect to a nozzle insertion direction on the steel pipe shaft, and a second head that ejects the abrasive in a direction that forms an obtuse angle. Shot blasting device.   The shot blasting device according to claim 1, wherein the second head is configured to be able to reach the back side of the steel pipe from the first head.   The shot blasting apparatus according to claim 1 or 2, wherein the abrasive jetting directions of the first head and the second head are different from each other in the circumferential direction.   The shot blasting device according to any one of claims 1 to 3, wherein the abrasive is sucked and collected from the end of the tube on the side where the nozzle is inserted.   5. The shot blasting apparatus according to claim 4, further comprising an inner plug for suppressing the diffusion of the abrasive from the nozzle to the back side of the steel pipe.   6. The shot blasting apparatus according to claim 5, further comprising an air blow nozzle for discharging the polishing material remaining in the steel pipe on the back side of the steel pipe from the inner plug.