JP2018008370A - Pipe grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe grinding device capable of preventing a grinding member from degrading in grinding performance due to friction heat.SOLUTION: A pipe grinding device comprises a plurality of grinding members 26 rotatably installed on a support shaft 24. Each grinding member 26 has a base plate section installed on the support shaft 24 and a grinding stone section 32 provided at an outer periphery of the base plate section. A spacer 34 is installed between the grinding members 26 arranged next to each other in a shaft center direction B of the support shaft 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a grinding apparatus for grinding an inner surface of a pipe.

  Conventionally, as this kind of grinding apparatus, as shown in FIG. 16, the grinding member 102 is moved in the axial direction A of the tube 101 with respect to the tube 101 rotatably supported, and the inner surface of the tube 101 is moved. There is something to grind. The grinding member 102 is provided at the tip of the rotating shaft 103.

  According to this, the tube 101 is rotated around the axial center, and the grinding member 102 is inserted into the tube 101 while being rotated together with the rotating shaft 103, and is moved in the axial direction A of the tube 101. Thereby, the grinding member 102 contacts the inner surface of the tube 101 and grinds the inner surface of the tube 101 while moving in the axial direction A of the tube 101.

  A pipe grinding apparatus as described above is described in, for example, Patent Document 1 below.

JP 2001-219344

  However, in the above conventional type, when the inner surface of the pipe 101 is ground by the grinding member 102, the grinding member 102 becomes high temperature due to frictional heat between the grinding member 102 and the inner surface of the pipe 101. There is a problem that the material becomes deteriorated and becomes brittle, and the grinding performance of the grinding member 102 is greatly lowered.

  An object of the present invention is to provide a pipe grinding apparatus capable of preventing a reduction in grinding performance of a grinding member due to frictional heat.

To achieve the above object, the first invention is a grinding apparatus for grinding an inner surface of a pipe while moving at least one of a pipe and a grinding member in the axial direction of the pipe with respect to the other.
A plurality of rotatable grinding members are provided on the support shaft,
The grinding member has a base part provided on the spindle and a grindstone part provided on the outer periphery of the base part,
A spacer is provided between the base parts of the grinding members adjacent in the axial direction of the support shaft.

  According to this, the tube is rotated around the axis, and the grinding member is brought into contact with the inner surface of the tube while rotating, and is moved in the axial direction of the tube. As a result, the inner surface of the tube is ground while the grinding member moves in the axial direction of the tube.

  At this time, frictional heat is generated by friction between the grindstone part of the grinding member and the inner surface of the pipe, but this frictional heat is transmitted from the grindstone part of the grinding member to the base part and dissipated from the base part, It is transmitted from the platform to the spacer and is also dissipated from the spacer. As a result, the dissipation (heat dissipation) of frictional heat is promoted and the temperature rise of the grindstone portion of the grinding member is suppressed, so that the grindstone portion can be prevented from becoming hot and deteriorating and becoming brittle. A reduction in grinding performance can be prevented.

  In addition, since the grinding members adjacent to each other in the axial direction of the support shaft are separated by a spacer, grinding waste generated when grinding the inner surface of the pipe can be easily performed between the grinding members adjacent to each other. To be discharged. Thereby, since the discharge | emission performance of grinding waste improves, the fall of the grinding performance of a grinding member can further be prevented.

In the tube grinding apparatus according to the second aspect of the present invention, a hole penetrating in the axial direction of the support shaft is formed in the base plate portion.
The spacer is configured so as not to block the hole.

According to this, since frictional heat is dissipated also from the hole of a base part, dissipation of frictional heat is accelerated | stimulated further.
In the pipe grinding apparatus according to the third aspect of the present invention, the base and the spacer are made of metal.

According to this, the frictional heat is easily transmitted from the grindstone part of the grinding member to the spacer through the base part, and the frictional heat can be dissipated from the base part and the spacer.
In the pipe grinding apparatus according to the fourth aspect of the present invention, a plurality of grindstone portions are provided at intervals in the circumferential direction of the base plate portion, and project outward in the radial direction from the outer periphery of the base plate portion.

  According to this, since the plurality of grindstone portions are provided in a state of being spaced apart in the circumferential direction of the platform portion, grinding waste generated when cutting the inner surface of the pipe is It is easily discharged from between the adjacent grindstone parts in the circumferential direction. Thereby, since the discharge | emission performance of grinding waste improves, the fall of the grinding performance of a grinding member can be prevented.

In the pipe grinding apparatus according to the fifth aspect of the invention, the grindstone portion has a mountain-shaped projection on the outer peripheral portion.
According to this, the cutting performance of the inner surface of the pipe is improved by the mountain-shaped projections of the grindstone portion of the rotating grinding member cutting the inner surface of the pipe.

In the pipe grinding apparatus according to the sixth aspect of the invention, the grindstone portion has a polygonal protrusion on the outer peripheral portion.
According to this, the cutting performance of the inner surface of the tube is improved by the polygonal protrusions of the grindstone portion of the rotating grinding member cutting the inner surface of the tube.

In the pipe grinding apparatus according to the seventh aspect of the invention, the protrusion has a corner at the end in the axial direction of the support shaft.
According to this, the grinding member moves in the axial direction of the tube while rotating, and the projection of the grindstone cuts the inner surface of the tube, whereby the inner surface of the tube is ground. At this time, since the projection has a corner at the end in the axial direction of the support shaft, the projection moves in the axial direction of the tube with the corner as the head. For this reason, the grinding member can be smoothly moved in the axial direction of the pipe.

In the pipe grinding apparatus according to the eighth aspect of the present invention, the projection has a corner at the end in the rotation direction of the grinding member.
According to this, the grinding member moves in the axial direction of the tube while rotating, and the projection of the grindstone cuts the inner surface of the tube, whereby the inner surface of the tube is ground. At this time, since the protrusion has a corner at the end in the rotation direction of the grinding member, the protrusion rotates with the corner as the head. For this reason, the grinding member can be smoothly rotated.

In the tube grinding apparatus according to the ninth aspect of the present invention, the projection has a guide surface for guiding the grinding waste between the grindstone portion and the platform portion.
According to this, when the projection of the grindstone portion of the rotating grinding member is cutting the inner surface of the pipe, grinding waste is generated. This grinding waste is generated between the grindstone portion and the base plate portion by the guide surface of the projection. It is easily discharged from between the grinding members. For this reason, the grinding | polishing waste discharge performance improves and it can prevent further the fall of the grinding performance of a grinding member.

  As described above, according to the present invention, when the inner surface of the pipe is being ground, frictional heat is generated due to friction between the grinding stone portion of the grinding member and the inner surface of the pipe. This frictional heat is generated from the grinding stone portion of the grinding member. It is transmitted to the base part and diffused from the base part, and is transmitted from the base part to the spacer and is also diffused from the spacer. As a result, the dissipation of frictional heat is promoted, and the temperature rise of the grindstone portion of the grinding member is suppressed, so that the grindstone portion can be prevented from becoming hot and deteriorating and becoming brittle. A decrease can be prevented.

1 is a side view of a pipe grinding apparatus according to a first embodiment of the present invention. It is a side view of the principal part of a grinding device. It is an exploded view of the principal part of a grinding device. FIG. 3 is an XX arrow view in FIG. 2. It is a side view of the grinding member of the grinding apparatus in the 2nd Embodiment of this invention. It is a side view of the principal part of the grinding device in the 3rd Embodiment of this invention. It is a perspective view of the grinding member of a grinding device. It is a XX arrow line view in FIG. It is a side view of the grinding member of the grinding device. It is an enlarged view of the protrusion of the grinding member of the grinding device. It is a partially expanded perspective view of the grinding member of the grinding apparatus in the 4th Embodiment of this invention. It is a side view of the principal part of the grinding device in the 5th Embodiment of this invention. It is a XX arrow line view in FIG. It is an enlarged perspective view of the grindstone part of the grinding device. It is a side view of the principal part of the grinding apparatus in the comparative example 1 described in Table 1. It is a side view of the principal part of the conventional pipe grinding apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
In the first embodiment, as shown in FIG. 1 to FIG. 4, 1 is a ductile cast iron straight pipe (ductile cast iron pipe), has an insertion slot 2 at one end, and a receptacle at the other end. 3. Reference numeral 10 denotes a support device for rotatably supporting the tube 1. The support device 10 includes a plurality of support rollers 11 that support the tube 1 in a horizontal posture from below, a press roller 12 that can be raised and lowered to press the tube 1 from above and prevent the tube 1 from jumping, and a support roller 11. Rotation drive means (not shown) for rotating the supported tube 1 around the axis.

  Reference numeral 20 denotes a grinding device for grinding the inner surface of the tube 1. The grinding device 20 includes a carriage 21 movable in the axial direction A of the tube 1, a vertically movable frame 22 provided on the carriage 21, a jack device (not shown) for raising and lowering the frame 22, A bearing device 23 provided on the bearing device 23, a support shaft 24 provided rotatably on the bearing device 23, a rotation drive device 25 such as a motor for rotating the support shaft 24, and a plurality of devices provided at the tip of the support shaft 24. The grinding member 26 is provided.

  The support shaft 24 includes a shaft main body portion 28, an attachment shaft portion 29 provided at the distal end of the shaft main body portion 28, and a cap 30 provided at the distal end portion of the attachment shaft portion 29. The attachment shaft portion 29 is attached to the tip of the shaft main body portion 28 by being detachably screwed via a screw. The cap 30 is attached to the tip end portion of the attachment shaft portion 29 by being detachably screwed via a screw.

The axial direction B of the support shaft 24 is the same as the axial direction A of the tube 1 supported by the support device 10.
Each grinding member 26 has a disk-shaped base part 31 detachably provided on the support shaft 24 and a plurality of grindstone parts 32 provided on the outer periphery of the base part 31. Spacers 34 are provided between the base portions 31 of the grinding members 26 adjacent in the axial direction B of the support shaft 24. Spacers 35 are also provided between the grinding member 26 and the end of the shaft main body 28 of the support shaft 24 and between the grinding member 26 and the cap 30 of the support shaft 24.

  A shaft hole 37 is formed in each of the center portion of the base plate portion 31 and the center portions of the spacers 34 and 35, and the mounting shaft portion 29 of the support shaft 24 is inserted into the shaft hole 37. Further, the mounting shaft 29 is provided with a non-rotating member (not shown) such as an embedding key, by which the grinding member 26 and the spacers 34 and 35 are relative to the mounting shaft 29. Thus, the rotational force of the support shaft 24 is transmitted to the grinding member 26 and the spacers 34 and 35 via the anti-rotation member, and the grinding member 26 and the spacers 34 and 35 are thereby prevented. And rotate together with the support shaft 24.

  A plurality of holes 38 penetrating in the axial direction B of the support shaft 24 are formed in the base plate portion 31. Each hole 38 is formed around the shaft hole 37 at a predetermined angle (for example, 60 ° in FIG. 4).

  The spacers 34 and 35 are annular members, and the spacers 34 and 35 have the same inner diameter and the same outer diameter, and the width C of the spacer 34 in the axial direction B is equal to the width D of the spacer 35 as shown in FIG. Bigger than. Further, as shown in FIG. 4, the distance L1 from the center of each spacer 34, 35 to the outer periphery is set to be equal to or less than the distance L2 from the center of the base plate portion 31 to the nearest edge of the hole 38. Thereby, each spacer 34 and 35 has the structure which does not block the hole 38 of the base part 31. FIG.

The base part 31 and the spacers 34 and 35 are each made of metal such as iron or stainless steel.
In addition, the material of the base part 31 and the spacers 34 and 35 may be a material other than iron or stainless steel as long as heat conductivity is good and sufficient strength is ensured.

  Each grindstone portion 32 includes diamond abrasive grains and is formed at predetermined intervals (20 ° in FIG. 4) at a predetermined interval in the circumferential direction of the base plate portion 31. Projects radially outward from the outer periphery.

  Each grindstone portion 32 has a plurality of mountain-shaped protrusions 41 on the outer peripheral portion. The ridge lines 42 at the tips of the protrusions 41 extend in the circumferential direction of the grinding member 26. As shown in FIGS. 2 and 3, the crest 41 a of each protrusion 41 of one grindstone portion 32 and the other grindstone portion 32 that are adjacent to each other in the circumferential direction of the grinding member 26 is in the axial direction B. Similarly, the valley 41b of each protrusion 41 is also in the same position in the axial direction B.

As shown in FIG. 2, the width E of the grinding member 26 in the axial direction B is equal to or smaller than the width C of the spacer 34. The outer diameter of the grinding member 26 is smaller than the inner diameter of the tube 1.
Hereinafter, the operation of the above configuration will be described.

  As shown in FIG. 1, the tube 1 is placed on the support roller 11 of the support device 10, pressed from above by the pressing roller 12, and rotated around the axis by the rotation driving means. The frame 22 of the grinding device 20 is moved up and down to adjust the height of the grinding member 26, and the support shaft 24 is rotated by the rotation drive device 25 to rotate the grinding member 26 in the same direction as the pipe 1.

  In this state, the carriage 21 is advanced, the grinding member 26 is inserted from one end of the tube 1 into the inside, the frame 22 is lowered, and the grinding member 26 is pressed against (in contact with) the inner surface of the tube 1 with an appropriate force. ). In this state, the carriage 21 is further advanced slowly, and the grinding member 26 is moved in the axial direction A within the pipe 1. As a result, the grinding member 26 moves in the axial direction A of the tube 1 while rotating to grind the inner surface of the tube 1, so that the oxide scale and the like on the inner surface of the tube 1 are removed.

  At this time, frictional heat is generated by friction between the grindstone portion 32 of the grinding member 26 and the inner surface of the tube 1. This frictional heat is transmitted from the grindstone portion 32 to the base plate portion 31, and the hole 38 of the base plate portion 31. Is transmitted from the base plate 31 to the spacers 34 and 35, and is also dissipated from the spacers 34 and 35. Thereby, the dissipation (heat dissipation) of frictional heat is promoted, and the temperature rise of the grindstone portion 32 is suppressed. Therefore, the grindstone portion 32 can be prevented from becoming high temperature and deteriorating and becoming brittle. A reduction in grinding performance can be prevented.

  Further, since the base part 31 and the spacers 34 and 35 are made of metal (for example, iron or stainless steel), the frictional heat is easily transmitted from the grindstone part 32 to the spacers 34 and 35 via the base part 31, and the frictional heat. Can be diffused from the base part 31 and the spacers 34 and 35.

  Further, since the grinding members 26 adjacent in the axial direction B are separated from each other via the spacer 34, the grinding waste generated when grinding the inner surface of the pipe 1 is between the grinding members 26 adjacent to each other. Is easily discharged into the tube 1. Thereby, since the discharge performance of grinding waste improves, the fall of the grinding performance of the grinding member 26 can further be prevented.

  Further, since the plurality of grindstone portions 32 are provided in a state of being spaced apart from each other at a predetermined interval in the circumferential direction of the base plate portion 31, grinding waste generated when cutting the inner surface of the tube 1 is It is easily discharged from between the adjacent grindstone portions 32 in the circumferential direction of the portion 31. Thereby, since the discharge | emission performance of grinding waste improves further, the fall of the grinding performance of the grinding member 26 can be prevented.

Moreover, the cutting performance of the inner surface of the tube 1 is improved by the mountain-shaped protrusion 41 of the grindstone portion 32 of the rotating grinding member 26 cutting the inner surface of the tube 1.
(Second Embodiment)
In the second embodiment, as shown in FIG. 5, the positions of the peaks 41 a of the protrusions 41 of one grindstone portion 32 and the other grindstone portion 32 that are adjacent to each other in the circumferential direction of the grinding member 26. And the position of the valley 41b are shifted in the axial direction B. That is, the position of the peak 41a of the protrusion 41 of the one grindstone part 32 and the position of the valley 41b of the protrusion 41 of the other grindstone part 32 coincide with each other in the axial direction B. The position of the valley 41b of the protrusion 41 of the grindstone 32 matches the position of the peak 41a of the protrusion 41 of the other grindstone 32.

According to this, the same operation and effect as the first embodiment described above can be obtained.
(Third embodiment)
In 3rd Embodiment, as shown in FIGS. 6-10, each grindstone part 32 has the processus | protrusion 50 of a rhombus (an example of a polygon) seeing from a radial direction outer side in an outer peripheral part. . That is, the outer end surface 50a of the protrusion 50 in the radial direction of the grinding member 26 is formed in a rhombus shape. Further, the protrusion 50 has first corners 50 b at both ends in the axial direction B of the support shaft 24, and has second corners 50 c at both ends in the rotation direction J of the grinding member 26. ing. Each of the first and second corner portions 50b and 50c is pointed in a V shape, the apex angle of the first corner portion 50b is an acute angle, and the apex angle of the second corner portion 50c is an obtuse angle.

  Further, the protrusion 50 has a guide surface 51 that guides the grinding scraps 52 between the two base plate parts 31 adjacent to the grindstone part 32. The guide surface 51 extends in a V shape in the axial direction B of the support shaft 24 from the second corner portion 50 c in the rotation direction J of the grinding member 26.

  As shown in FIG. 9, the orientation of the protrusion 50 is such that the longer diagonal line 53 of the protrusions 50 intersects the straight line 54 parallel to the axis 24 a of the support shaft 24 at a predetermined angle G. Is inclined in the circumferential direction of the grinding member 26.

Hereinafter, the operation of the above configuration will be described.
When the grinding member 26 rotates and moves in the axial direction A of the tube 1 to grind the inner surface of the tube 1, the diamond-shaped protrusions 50 of the grindstone portion 32 of the rotating grinding member 26 are formed on the tube 1. By cutting the inner surface, the cutting performance of the inner surface of the tube 1 is improved.

  As shown in FIG. 10, the grinding dust 52 generated at this time is scraped to the both guide surfaces 51 from the second corner portion 50 c of the protrusion 50, and the two base plate portions 31 adjacent to the grinding member 26 by the guide surfaces 51. Since it is guided in between, it is easily discharged into the space between the grinding members 26. For this reason, the discharge | emission performance of the grinding waste 52 improves and the fall of the grinding performance of the grinding member 26 can further be prevented.

  Further, since the protrusion 50 moves in the axial direction A of the tube 1 with the first corner 50b as the head, the grinding member 26 can be smoothly moved in the axial direction A. Furthermore, since the protrusion 50 rotates with the second corner portion 50c as the head, the grinding member 26 can rotate smoothly.

(Fourth embodiment)
In the said 3rd Embodiment, as shown in FIG. 7, each grindstone part 32 has the rhombus-shaped protrusion 50 which is an example of a polygon in the outer peripheral part, but 4th Embodiment. Then, as shown in FIG. 11, each grindstone part 32 has a rectangular protrusion 60 which is another example of a polygon on the outer peripheral part. That is, the outer end surface 60a of the protrusion 60 in the radial direction of the grinding member 26 is formed in a rectangular shape when viewed from the outside in the radial direction.

Hereinafter, the operation of the above configuration will be described.
When the grinding member 26 rotates and moves in the axial direction A of the tube 1 to grind the inner surface of the tube 1, the rectangular protrusion 60 of the grindstone portion 32 of the rotating grinding member 26 is formed on the tube 1. By cutting the inner surface, the cutting performance of the inner surface of the tube 1 is improved.

  In the third and fourth embodiments, the rhombus or rectangular protrusions 50 and 60 are provided as an example of a polygon. However, a rhombus or a rectangle other than the rectangle may be used, or a triangle, pentagon or more may be used. It may be.

(Fifth embodiment)
In the fifth embodiment, as shown in FIGS. 12 to 14, each grindstone portion 32 has a quadrangular pyramid-shaped protrusion 65 with a sharp tip on the outer peripheral portion. The protrusions 65 have first corners 65 a at both ends in the axial direction B of the support shaft 24, and second corners 65 b at both ends in the rotation direction J of the grinding member 26. .

Hereinafter, the operation of the above configuration will be described.
When the grinding member 26 rotates and moves in the axial direction A of the tube 1 to grind the inner surface of the tube 1, the quadrangular pyramid-shaped protrusions 65 of the grindstone 32 of the rotating grinding member 26 are in the tube 1. By cutting the inner surface, the cutting performance of the inner surface of the tube 1 is improved.

  Further, since the protrusion 65 moves in the axial direction A of the tube 1 with the first corner 65a as the head, the grinding member 26 can move smoothly in the axial direction A. Furthermore, since the protrusion 50 rotates with the second corner 65b as the head, the grinding member 26 can be smoothly rotated.

In the fifth embodiment, the quadrangular pyramid projection 65 is provided, but the projection is not limited to a quadrangular pyramid, and may be a polygonal pyramid shape such as a triangular pyramid or a pentagonal pyramid or a conical shape, for example. .
Table 1 below shows the test results showing the evaluation of grinding the inner surface of the pipe 1 using five types of grinding members 26 and 91 (Comparative Example 1, Examples 1 to 4). Among them, in Comparative Example 1, as shown in FIG. 15, the width E of one grinding member 91 is 50 mm, the number of grinding members 91 is two, and the total width E of the grinding members 91 is 100 mm (= grinding). The width of the member 91 × the number) and the shape of the protrusion 93 of the grindstone 92 are rectangular, and no spacer is provided between the two grinding members 102, and no space is formed.

  Further, in Example 1, as shown in the first embodiment (see FIG. 2), the shape of the protrusion 41 of the grindstone portion 32 is formed in a mountain shape, and the width of one grinding member 26 is obtained. E is 20 mm, the number of mounting of the grinding members 26 is 3, and the spacers 34 and 35 are provided to form a space between the grinding members 26.

In Example 2, as shown in the third embodiment (see FIG. 6), the shape of the protrusion 50 of the grindstone 32 is formed in a rhombus shape.
In Example 3 and Example 4, as shown in the fourth embodiment (see FIG. 11), the shape of the protrusion 60 of the grindstone portion 32 is formed in a rectangular shape. Example 3 and Example 4, the width E and the number of attachments of the grinding member 26 are different.

  The pipe 1 was a ductile cast iron straight pipe (ductile cast iron pipe) having a diameter of 150 mm and a total length of 5 m, on which an oxide film of 100 μm iron was formed on the inner surface.

  As an evaluation, the time required to completely remove the oxide film on the inner surface of the tube 1 (hereinafter referred to as the removal time) was measured for each of Comparative Example 1 and Examples 1 to 4, and With the removal time as 1, the ratio of the removal times of Examples 1 to 4 is described.

  Further, the inner surfaces of a predetermined number of tubes 1 are ground for a certain time, and then powder coating is performed on the inner surfaces of each tube 1 to form a coating film having a film thickness of 400 μm. The failure rate when the inspection is performed is measured for each of Comparative Example 1 and Examples 1 to 4, and the failure rate of Comparative Example 1 is set to 1, and the failure rate of each of Examples 1 to 4 is measured. Ratios are listed.

  Moreover, about the pipe 1 which passed the pinhole test | inspection of the said powder coating, the adhesive force of a coating film was measured, the coating film adhesive force of the comparative example 1 was set to 1, and the coating film of Example 1- Example 4 The ratio of adhesion was described.

  According to Table 1 below, in Examples 1 to 4, the total width E of the grinding member 26 is smaller than that in Comparative Example 1, but since the spacers 34 and 35 are provided, the dissipation of frictional heat and the grinding dust Emissions are promoted. This prevents a decrease in the grinding performance of the grinding member 26, the ratio of the removal times of Examples 1 to 4 is smaller than 1, and the oxide film on the inner surface of the tube 1 is formed in a shorter time than Comparative Example 1. It is thought that it can be completely removed.

  The total width E of the grinding member 26 of Example 4 is smaller than that of Example 3, but Example 4 has the same evaluation as Example 3. This is because, in the fourth embodiment, the width E of each grinding member 26 is narrower and the total number of the spacers 34 and 35 is larger than that in the third embodiment, and the dissipation of frictional heat and the discharge of grinding dust are promoted. it is conceivable that.

  In addition, with respect to the ratio of the removal time, Example 1 and Example 2 are shorter than Example 3 and Example 4. About this, by making the shape of the protrusion 41 of the grindstone 32 into a mountain shape or a rhombus shape, the contact area between the protrusion 41 and the inner surface of the tube 1 is reduced, and the protrusion 41 comes into contact with the inner surface of the tube 1. It is thought that this is because the grinding performance was improved by improving the surface pressure.

  Moreover, about the ratio of the coating film adhesion force, all of Examples 1 to 4 are larger than Comparative Example 1, and the coating films in Examples 1 to 4 are those of Comparative Example 1. Rather than being firmly fixed to the inner surface of the tube 1. In addition, when the oxide scale remains on the inner surface of the tube 1, the coating film is easily peeled off from the portion of the oxide scale, and the adhesion of the coating film is reduced. Therefore, as described above, Examples 1 to 4 have a larger value than that of Comparative Example 1 with respect to the ratio of the adhesion strength of the coating film, which means that the oxide scale on the inner surface of the tube 1 is removed. It is proved that Examples 1 to 4 are superior to Comparative Example 1.

  In each of the above embodiments, as shown in FIG. 1, the tube 1 is fixed in the axial direction A, and the inner surface of the tube 1 is ground while moving the grinding member 26 in the axial direction A with respect to the tube 1. However, the inner surface of the tube 1 may be ground while fixing the grinding member 26 in the axial direction A and moving the tube 1 in the axial direction A with respect to the grinding member 26. Alternatively, the inner surface of the tube 1 may be ground by moving both the tube 1 and the grinding member 26 in directions opposite to each other in the axial direction A (approaching and separating directions). When the tube 1 is moved in the axial direction A, for example, the support device 10 may be configured to be movable in the axial direction A.

  In each of the above embodiments, as shown in FIGS. 4, 8, and 13, each hole 38 does not overlap with the spacers 34, 35, but overlaps with a part of the spacers 34, 35 so as to overlap each hole 38. Only a part of these may be covered with spacers 34 and 35. That is, it is sufficient that the entire surface of each hole 38 is not blocked by the spacers 34 and 35.

  In the above embodiments, the number of the grinding members 26, the spacers 34 and 35, the grindstone 32, the projections 41, 50, 60, and 65 are not limited to those illustrated. Moreover, although the duct 1 made of ductile cast iron was mentioned, it is not limited to the product made of ductile cast iron.

DESCRIPTION OF SYMBOLS 1 Pipe | tube 20 Grinding device 24 Support shaft 26 Grinding member 31 Base part 32 Grinding stone part 34 Spacer 38 Hole 41, 50, 60, 65 Protrusion 50b 1st corner | angular part 50c 2nd corner | angular part 51 Guide surface 52 Grinding waste 65a 1st 1 corner 65b 2nd corner A Axial direction B of the tube B Axial direction J of the spindle J Rotation direction of the grinding member

Claims (9)

A grinding device for grinding an inner surface of a pipe while moving at least one of a pipe and a grinding member relative to the other in the axial direction of the pipe,
A plurality of rotatable grinding members are provided on the support shaft,
The grinding member has a base part provided on the spindle and a grindstone part provided on the outer periphery of the base part,
A pipe grinding apparatus, wherein a spacer is provided between the base parts of the grinding members adjacent in the axial direction of the support shaft. A hole penetrating in the axial direction of the support shaft is formed in the platform,
2. The pipe grinding apparatus according to claim 1, wherein the spacer is configured not to block the hole. The pipe grinding apparatus according to claim 1 or 2, wherein the base part and the spacer are made of metal. 4. The grindstone portion is provided with a plurality of intervals in the circumferential direction of the base plate portion, and protrudes radially outward from the outer periphery of the base plate portion. The pipe grinding apparatus according to item 1. The pipe grinding apparatus according to any one of claims 1 to 4, wherein the grindstone portion has a mountain-shaped protrusion on an outer peripheral portion thereof. The pipe grinding apparatus according to any one of claims 1 to 4, wherein the grindstone portion has a polygonal protrusion on an outer peripheral portion thereof. The pipe grinding apparatus according to claim 6, wherein the protrusion has a corner at an end in the axial direction of the support shaft. The pipe grinding apparatus according to claim 6 or 7, wherein the protrusion has a corner at an end in a rotation direction of the grinding member. The pipe grinding apparatus according to any one of claims 6 to 8, wherein the protrusion has a guide surface that guides grinding waste between the grindstone portion and the platform portion.

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