JP2006224267A - Pipe inside grinding apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe inside grinding apparatus and method for grinding an inner surface of a circular pipe made of stainless steel or the like, even if it has a large diameter. <P>SOLUTION: There is provided a grinding wheel 2 of which outside diameter is set to be smaller than the inside diameter of the circular pipe and which has an iron core 3 in it so as to grind the inner surface of the circular pipe 1 by rotation. A flexible cantilever shaft 6 is provided to rotatively drive the wheel 2, and a circular pipe drive section is provided to rotatively drive the circular pipe. A magnet 5 generating a line of magnetic force is provided so as to travel in the axial direction of the circular pipe 1 at such a position as to face, sandwiching the grinding wheel 2 and the circular pipe 1 and so as to develop an attraction force against the iron core 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an in-pipe grinding apparatus and an in-pipe grinding method for grinding an inner surface of a circular pipe made of stainless steel or the like, particularly a large diameter exceeding 10 mm and made of a nonmagnetic material.

  Stainless steel pipes have high durability and corrosion resistance. Currently, long stainless steel pipes with high-precision inner surfaces are used in food and pharmaceutical manufacturing. It is required to be processed and mirror-finished.

  Conventionally, an electropolishing method has been widely known as a method of processing the inner surface of a circular tube such as stainless steel. In the electrolytic polishing method, for example, as shown in FIG. 12, the circular tube 31 is immersed in an electrolytic solution 35 in a tank 33 using a fishing rod 37, and a voltage is applied to the circular tube 31 positively (positively). Wiring 39, a cathode 41 to which a negative (negative) voltage is applied in the electrolytic solution 35, and its wiring 43 are provided, and the temperature of the electrolytic solution 35 is stirred by a stirrer 47 while the temperature of the temperature regulator 45 is adjusted. However, by applying a positive voltage to the circular tube 31 and a negative voltage to the cathode 41, an electrolysis phenomenon is caused to elute minute convex portions on the inner surface of the circular tube 31, and the inner surface has a smooth gloss. The surface finish is provided. Such an electrolytic polishing method is suitably used for finishing the inner surface of a thin circular tube having a diameter of 10 mm or less. A thin circular tube having a diameter of 10 mm or less is usually formed by extrusion.

  However, since the above conventional electropolishing method cannot be processed to correct the size and shape, the steel plate is bent into a tubular shape like a circular tube having a diameter of more than 10 mm, and the boundary surface between the inner side and the outer side. Therefore, there is an inconvenience that it cannot be used for the circular pipe welded from the above. This is because weld marks (beads) raised along the boundary surface are formed on the inner surface of the circular pipe manufactured by welding as described above, and such weld marks cannot be removed by the electrolytic polishing method. Because.

  Further, in the conventional electropolishing method, it is necessary to use a large amount of the electrolytic solution 35. Therefore, it takes time to process the electrolytic solution 35 after use, and the load on the environment when it is discarded is large. Has also occurred.

  Therefore, it is known to use a honing method for finishing the inner surface of a large-diameter circular pipe having such a welding mark. In the honing method, as shown in FIG. 13, several rod-shaped grindstones 52 of a honing tool are applied to an inner surface 51 a of the circular pipe 51 by a spring or hydraulic pressure, with respect to a circular pipe 51 having a large diameter in which the honing tool enters. While pushing, the honing tool 53 is rotated and reciprocated in the axial direction to finish the inner surface of the circular pipe 51.

  Such a honing method has the advantage that high-precision and high-quality finishing can be performed, and also requires only a small amount of grinding fluid during grinding, so that the above-mentioned disadvantages can be avoided with less environmental burden.

  However, in the conventional honing method, since the rotational movement of the grindstone 52 cannot be accelerated in order to suppress the temperature rise of the grindstone 52, there is a problem that the grinding efficiency is low and the efficiency is low. The conventional electrolytic polishing method has the same problem in terms of low efficiency.

  In addition, in the conventional honing method, the honing tool 53 is also long in order to cope with the long circular tube 51, and the apparatus configuration becomes large, and the temperature during processing is increased. This causes problems such as wear of the grindstone 52 and deterioration of the processing quality of the inner surface of the circular pipe 51.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an in-pipe grinding apparatus and an in-pipe grinding apparatus capable of grinding a large-diameter circular pipe, in particular, an inner surface of a steel pipe efficiently, quickly and accurately. To realize a grinding method.

  In order to solve the above problems, an in-pipe grinding apparatus according to the present invention has an outer diameter smaller than the inner diameter of the circular pipe, and has a magnetic body inside, and a grindstone for grinding the inner surface of the circular pipe by rotation, , A grindstone driving unit for rotationally driving the grindstone, a circular tube driving unit for rotationally driving the circular tube, and movable in the axial direction of the circular tube at a position facing the grindstone and the circular tube And a magnetic force generating part for generating a magnetic force line so as to generate an attractive force with respect to the magnetic body.

  According to the above configuration, the magnetic body is provided inside the grindstone, and the magnetic force generating portion that generates the magnetic force lines so as to generate an attractive force against the magnetic body is positioned at the position where the grindstone and the circular pipe are opposed to each other with the shaft of the circular pipe. Since the grindstone is provided so as to be movable in the direction, even if the outer diameter of the grindstone is set smaller than the inner diameter of the circular tube, the grindstone can be pressed against the inner surface of the circular tube by the suction force to maintain the contact state.

  Thus, in the above configuration, the grindstone is rotated by the grindstone driving unit while contacting the grindstone with the inner surface of the circular tube, and the circular tube is rotated by the circular tube driving unit, so that the grindstone rotates the entire inner surface of the circular tube. The peripheral surface can be ground.

  In addition, in the above-described configuration, it is possible to increase the efficiency of grinding of the inner peripheral surface and avoid deterioration of work quality by rotating the grindstone at a high speed by the grindstone driving unit.

  The above-mentioned in-pipe grinding apparatus preferably further includes a stabilizing portion for stabilizing the movement of the grindstone.

  The in-pipe grinding apparatus preferably further includes a magnetic force movement control unit that moves the magnetic force generation unit. In the above-mentioned in-pipe grinding apparatus, the magnetic force generator may be a permanent magnet.

  In the in-pipe grinding apparatus, it is desirable that the grindstone driving unit and the circular tube driving unit are set so as to rotate the grindstone and the circular tube in opposite directions.

  In the above-mentioned in-pipe grinding apparatus, it is preferable that the grindstone driving unit includes a flexible cantilever rotating shaft that can transmit a rotational driving force even if it is bent. According to the above configuration, since the flexible cantilever rotary shaft that can transmit the rotational driving force even if bent, the rotational driving force can be transmitted to the grindstone even if the circular tube is long. It can be suitably used for grinding the inner surface of a circular pipe.

  In the above-mentioned in-pipe grinding apparatus, the circular pipe may be provided with a welding mark obtained by bending a plate into a tubular shape by bending and welding between adjacent plates.

  In order to solve the above problems, the in-pipe grinding method according to the present invention sets a grindstone for grinding the inner surface of a circular pipe by rotation so that the outer diameter of the grindstone is smaller than the inner diameter of the round pipe, The grindstone and the circular tube are rotated while the outer peripheral surface of the grindstone is in contact with the inner peripheral surface of the circular tube, and the grindstone is moved in the axial direction of the circular tube while rotating the grindstone, and the grindstone is rotated. In this case, the circular tube is pressed while being moved.

  According to the above method, the wheel is pressed against the circular pipe while rotating and moving. Therefore, even if the outer diameter of the grindstone is set smaller than the inner diameter of the circular pipe, the grindstone is in contact with the inner surface of the circular pipe. It can be maintained by the above pressing.

  Thereby, the said method can grind the whole surrounding surface of the inner surface of a circular tube with the said grindstone by rotating a grindstone in contact with the inner surface of a circular tube, and rotating the said circular tube. In addition, the above method can increase the efficiency of the grinding of the inner peripheral surface and avoid the deterioration of the processing quality by rotating the grindstone at a high speed.

  In the above-mentioned in-pipe grinding method, it is desirable to set so that the grindstone and the circular tube are rotated in opposite directions when the grindstone and the circular tube are respectively rotated.

  In the in-pipe grinding method, a magnetic body is provided inside the grindstone, and is further movable in the axial direction of the circular pipe at a position facing the grindstone and the circular pipe, and has an attractive force against the magnetic body. It is preferable to generate lines of magnetic force so as to generate pressure and press the grindstone against the circular pipe. In the in-pipe grinding method, the grindstone may be rotationally driven through a flexible cantilever shaft that can transmit a rotational driving force even if it is bent.

  As described above, the in-pipe grinding apparatus according to the present invention has an outer diameter smaller than the inner diameter of the circular pipe, includes a magnetic body therein, and grinds the inner surface of the circular pipe by rotation, and the whetstone A grindstone drive unit for rotationally driving, a circular tube drive unit for rotationally driving the circular tube, and movable in the axial direction of the circular tube at a position facing the grindstone and the circular tube, and And a magnetic force generator that generates magnetic lines of force so as to generate an attractive force with respect to the magnetic body.

  Therefore, in the above configuration, since the magnetic body inside the grindstone is provided and the magnetic force generating part that generates the magnetic force lines is generated so as to generate an attractive force against the magnetic body, the outer diameter of the grindstone is made smaller than the inner diameter of the circular tube. Even if it is set to a small value, by rotating the grindstone at a high speed, it is possible to increase the efficiency of grinding the inner peripheral surface and to avoid the deterioration of the machining quality as compared with the conventional honing method.

  In the in-pipe grinding method according to the present invention, as described above, the grindstone for grinding the inner surface of the circular pipe by rotation is set so that the outer diameter of the grindstone is smaller than the inner diameter of the circular pipe, The grindstone and the circular tube are respectively rotated while the surface is in contact with the inner peripheral surface of the circular tube, and the grindstone is moved in the axial direction of the circular tube while the grindstone is rotated, and the grindstone is rotated and moved. However, it is a method of pressing against the circular pipe.

  Therefore, the above method presses the circular pipe while rotating and moving the grindstone. Therefore, even if the grindstone is rotated at a high speed by setting the outer diameter of the grindstone to be smaller than the inner diameter of the circular pipe, Compared with the honing method, it is possible to increase the efficiency of grinding the inner peripheral surface and to prevent the deterioration of the processing quality.

  Each embodiment of the in-pipe grinding apparatus and the in-pipe grinding method according to the present invention will be described below with reference to FIGS. The above-mentioned in-pipe grinding apparatus is suitable for finishing the inner surface of a circular pipe in which, for example, a stainless steel (SUS304) steel plate is formed into a spiral shape by bending and welded between adjacent steel plates, particularly for mirror finish It can be used. On the inner surface of the circular pipe obtained by such welding, weld marks (beads) serving as convex portions are formed.

  In the above-mentioned in-pipe grinding apparatus, as shown in FIGS. 1 and 2, a grindstone 2 for grinding the inner surface of a circular pipe 1 such as stainless steel by rotation is provided in a columnar shape. The grindstone 2 has an outer diameter smaller than the inner diameter of the circular tube 1 and includes an iron core (magnetic body) 3 inside.

  In addition, a flexible cantilever shaft (grinding wheel drive unit) 6 for rotationally driving the grindstone 2 has one end attached to the rotating shaft of the grindstone 2. The other end of the flexible cantilever shaft 6 is connected to a motor (grinding wheel drive unit) 8. The flexible cantilever shaft 6 can transmit a rotational driving force from one end portion to the other end portion even when bent, and is rotationally driven by a motor 8.

  Further, a circular tube support portion (circular tube driving portion) 7a for supporting the circular tube 1 rotatably and substantially horizontally is mounted on the support base 7. Therefore, the circular tube support portion (circular tube drive portion) 7a includes the driven wheels (circular tube drive portion) 9 so that the circular tube 1 can be supported rotatably and substantially horizontally. Yes. Each driven wheel 9 is formed with a flange portion 9a extending on the axial end portion of the circular tube 1, and each end portion of the circular tube 1 is sandwiched between the flange portions 9a, thereby On the support base 7, the movement of the circular tube 1 in its axial direction is restricted.

  In addition, in order to rotationally drive the circular tube 1, a main driving wheel (circular tube driving unit) 11 that rotates in contact with the outer peripheral surface of the circular tube 1 is interposed between each driven wheel 9 and each driven wheel 9. It is provided so that the circular tube 1 is sandwiched therebetween. The main driving wheel 11 is rotationally driven by a motor (circular tube drive unit) 12 via a belt (circular tube drive unit) 14. Therefore, the circular tube 1 is rotationally driven in the circumferential direction of the circular tube 1 by the rotational drive by the main driving wheel 11. Instead of the belt 14, driving force transmission means such as a gear can be used.

  Then, a magnet (magnetic force generator) 5 that generates a magnetic force line so as to generate an attractive force with respect to the iron core 3 moves in the axial direction of the circular tube 1 at a position facing the grindstone 2 and the circular tube 1. It is provided as possible. Further, a magnetic force movement control unit 4 for moving the magnet 5 in the axial direction in order to move the grindstone 2 in the axial direction is provided on the support base 7. In the present embodiment, the magnet 5 is a permanent magnet that is a rare earth magnet, but an energized coil can be used instead.

  Further, a grindstone guide cable (stabilizing portion) 10 for stably moving the grindstone 2 in the axial direction of the circular tube 1 within the circular tube 1 is an end portion to which the flexible cantilever shaft 6 of the grindstone 2 is attached. The grindstone 2 is rotatably mounted on the rotation shaft at the end opposite to the above. Moreover, the tension | pulling tension | tensile_strength which pulls the grindstone 2 between the grindstone guide cables 10 with the flexible cantilever shaft 6 is applied by the weight etc., and the movement state of the grindstone 2 and the contact state to the inner surface of the circular pipe 1 are stabilized. It is possible.

  Such motors 8 and 12 are set to rotate the grindstone 2 and the circular pipe 1 in opposite directions. The grindstone 2 and the circular tube 1 may be rotated in the same direction. In that case, the linear velocity of the outer peripheral surface of the rotating grindstone 2 is set to the line of the inner peripheral surface of the rotating circular tube 1. It is preferable that the linear velocity of the outer peripheral surface of the grindstone 2 is set so that the relative velocity with respect to the linear velocity of the inner peripheral surface of the rotating circular tube 1 is larger than the speed.

  Next, the in-pipe grinding method according to the present invention will be described. In the in-pipe grinding method, first, the grindstone 2 for grinding the inner surface of the circular tube 1 by rotation is formed so that the outer diameter of the grindstone 2 is smaller than the inner diameter of the circular tube 1. Subsequently, the grindstone 2 and the circular tube 1 are rotated while the outer peripheral surface of the grindstone 2 is in contact with the inner peripheral surface of the circular tube 1. On the other hand, while rotating the grindstone 2, the inside of the circular tube 1 is moved by the movement of the magnet 5 in the axial direction of the circular tube 1, preferably reciprocating. At this time, while rotating the grindstone 2 and moving the inside of the circular tube 1 in the axial direction, the outer peripheral surface (that is, the grindstone surface) of the grindstone 2 is pressed against the inner surface of the circular tube 1 to grind the inner surface. Process.

  When the grindstone 2 and the circular tube 1 are rotated in this way, the grindstone 2 and the circular tube 1 are rotated in opposite directions, and the linear velocity of the outer peripheral surface of the rotating grindstone 2 is changed to that of the rotating circular tube 1. It is preferable to set so as to be larger than the linear velocity of the inner peripheral surface.

  Further, an iron core 3 as a magnetic body is provided inside the grindstone 2, and is movable in the axial direction of the circular tube 1 at a position facing the grindstone 2 and the circular tube 1. On the other hand, it is desirable to generate lines of magnetic force so as to generate an attractive force and press the grindstone 2 against the inner surface of the circular tube 1. Furthermore, it is preferable that the grindstone 2 is rotationally driven via the flexible cantilever shaft 6 that can transmit the rotational driving force even if it is bent, because it can be suitably applied to the long circular tube 1.

  The in-pipe grinding method and the in-pipe grinding apparatus according to the present invention have the above-mentioned circular pipe as long as the grinding stone 2 enters a thick circular pipe or a circular pipe with a weld mark (bead) as a processing target. For example, mirror finishing can be performed by grinding a surface that does not exist.

  Further, the in-pipe grinding method and the in-pipe grinding apparatus according to the present invention rotate the grindstone 2 attached to the tip of the flexible cantilever shaft 6 at high speed and perform grinding while reciprocating the inner surface of the rotated circular pipe 1. The grindstone 2 is attracted to the inner surface of the circular tube 1 by the magnetic force of the magnet 5 from the outside of the tube 1, and the grindstone 2 obtains a force for processing the inner surface of the circular tube 1, and the grindstone 2 rotated at high speed dances in the circular tube 1 ( Unstable movements) can be prevented and the grinding process can be stabilized.

  As a result, the apparatus and method of the present invention enables high-efficiency and high-quality grinding with the grinding wheel 2 that rotates at high speed, and also enables dimension and shape correction (bead removal). In addition, the apparatus and method of the present invention can reduce the cost of the long circular pipe 1 compared to the conventional apparatus by adopting the flexible cantilever shaft 6 and can reduce the cost. Since only the grinding fluid needs to be used, the burden on the environment can be reduced.

  Next, the results of examination of each grinding condition of the in-pipe grinding method and the in-pipe grinding apparatus according to the present invention will be described. As each grinding condition, the rotational speed of the circular tube 1, the rotational speed of the grindstone 2, the feed speed, and the grain size of the grindstone can be mentioned. As a rocking (reciprocating) device for the grindstone 2, a table of a vertical grinder (Malto) was used. As the circular pipe (work material) 1, a stainless steel pipe (SUS304) was used. CBN (resin bond, metal bond) wheel and SD (resin bond, metal bond) wheel were used for the grindstone. A rare earth magnet was used as the magnet 5 for attracting the grindstone 2. Details of the test conditions are shown in Table 1.

(Grinding test results)
As a result of the preliminary test, it was found that by scratching the corner of the grindstone 2 (corner at the end of the rotation axis direction), scratches generated on the grinding surface could be suppressed. used. Since there is a bead step on the inner surface of the circular tube 1 which is a stainless steel tube used in the test, the test was started after grinding down before the test. In order to evaluate the grinding results, as shown in FIG. 3, the change in the inner diameter of the circular tube 1 (grinding amount Δr) is measured with a micrometer, and the surface roughness in the axial direction is measured with a surface roughness meter (Form Talysurf, S4C). It was measured by.

(Effect of grinding stone 2 grain size and abrasive grain type on grinding)
The results of examining the influence of the grindstone particle size on the grinding performance are shown in FIGS. 4 (a) and 4 (b), respectively. As the grindstone 2, CBN170, CBN325, and SD1000 metal bond diamond grindstones were used. The grinding conditions are: the circular tube rotational speed, which is the rotational direction linear velocity on the inner surface (inner peripheral surface) of the circular tube 1, 80 m / min, and the grinding wheel rotational speed, which is the rotational direction linear velocity of the outer peripheral surface of the grindstone 2, is 80 m. The feed speed, which is the moving speed in the axial direction in the circular tube 1, was 1.2 m / min.

  In any grindstone 2, the grinding amount increased in proportion to the processing time. Moreover, the processing efficiency improved as the abrasive grains were coarse. The surface roughness was improved with respect to the processing time, but after the processing time of 10 minutes, the CBN170 metal bond grindstone was improved only to Ry = 5.0 μm and the CBN325 metal bond was improved to Ry = 3.0 μm. On the other hand, when an SD1000 grindstone was used, Ry was improved to 1.4 μm and polished to a sub-mirror surface.

(Effect on grinding when the rotation speed is changed)
The results of investigating the effects of the grindstone rotation speed and the circular tube rotation speed are shown in FIGS. 5 (a), 5 (b), 6 (a), and 6 (b), respectively. As the grindstone 2, a CBN325 metal bond grindstone was used, and the feed rate was set to 1.2 m / min.

  When the grinding wheel rotation speed was increased, the grinding amount increased, but the surface roughness Ry was rather deteriorated. The rotating speed of the circular tube was changed to 40 m / min (FIGS. 5A and 5B) and 80 m / min (FIGS. 6A and 6B), but the grinding amount and surface roughness were changed. No effect was observed.

(Effect of change in feed rate on grinding)
Next, the influence on the grinding performance when the feed rate is changed is shown in FIGS. 7 (a) and 7 (b), respectively. The grindstone 2 was a CBN325 metal bond grindstone. The test was performed with the circular tube rotation speed of 80 m / min, the grindstone rotation speed of 80 m / min, and the feed rates were changed to 0.6 m / min, 1.2 m / min, and 1.8 m / min. At a slow feed rate of 0.6 m / min, the grinding amount was improved over other feed rate conditions. On the other hand, the surface roughness was not improved much.

(Effect of magnetic force on grinding)
As shown in FIG. 8, the influence of grinding on the use of the magnet 22 with the magnet increased to two to increase the magnetic force was examined. The grinding results are shown in FIG. 9 (a) and FIG. 9 (b), respectively. An SD1000 metal bond grindstone was used as the grindstone 2, and the circular tube rotation speed was 80 m / min, the grindstone rotation speed was 80 m / min, and the feed speed was 1.2 m / min. From the results, when the magnetic force was increased with two magnets, the grinding amount increased, but the surface roughness was not improved.

(Examination of mirror finish conditions)
From the test results so far, the surface roughness reached when the optimum conditions for mirror finishing were applied was investigated. As the grinding stone 2, fine SD1000 and SD2000 resin bond diamond grinding stones were used. As grinding conditions, the results of grinding using the conditions where the most improvement in surface roughness is expected (grinding wheel rotational speed 80 m / min, circular pipe rotational speed 80 m / min, feed speed 1.8 m / min) are shown in FIG. .

  As a result of grinding for 25 minutes with an SD1000 resin bond grindstone, the inner surface of the circular tube 1 was improved to Ry = 0.71 μm and polished to a mirror surface. Further, after grinding for 15 minutes with an SD1000 resin bond grindstone, the surface roughness was improved to Ry = 0.42 μm as a result of grinding for 10 minutes after replacing with an SD2000 resin bond grindstone. At that time, as shown in FIG. 11, the inner surface of the circular tube 1 had a mirror finish so that characters of the printed matter placed below could be discriminated by the inner mirror surface.

(Conclusion of the test)
A magnetically assisted grinding wheel adsorption grinding method in which a grinding wheel 2 rotated at high speed is attracted to the inner surface of the circular pipe 1 using a magnet 5 for the purpose of high-efficiency and high-quality machining of the inner surface of the circular pipe 1 such as a stainless steel pipe. The grinding performance was investigated. The results obtained are shown below.
(1) The processing efficiency increased with the grinding wheel 2 having a larger abrasive grain size. To obtain a mirror-like surface roughness, a fine grinding stone of SD1000 or less is required.
(2) Grinding conditions vary depending on the processing efficiency and surface roughness, but it seems to be effective to reduce the wheel rotation speed in order to obtain good surface roughness.
(3) When processing was performed under conditions suitable for mirror finishing, it was possible to polish to a mirror surface of Ry = 0.42 μm.

  The in-pipe grinding apparatus and in-pipe grinding method of the present invention can be suitably used for smoothing and mirror finishing of the inner surface of a circular pipe, such as a large-diameter stainless steel pipe. Can be suitably used.

The principal part of embodiment in the pipe grinding apparatus and pipe grinding method which concerns on this invention is shown, (a) is a side view, (b) is sectional drawing. The said pipe grinding apparatus and the pipe grinding method are shown, (a) is a side view, (b) is front sectional drawing. It is sectional drawing which shows each measurement item of the test as described in this Embodiment, (a) shows grinding amount (DELTA) r and (b) shows surface roughness Ry. As an example of the above test, it is a graph showing the test results of examining the influence of the grindstone size and abrasive grain type on grinding, where (a) shows the cumulative grinding amount and (b) shows the surface roughness Ry. As another example of the above test, it is a graph showing the test results of examining the influence on grinding when the rotating speed of the grindstone is changed while fixing the rotating speed of the circular tube to 40 m / min. The amount of grinding, (b), indicates the surface roughness Ry. As still another example of the above-mentioned test, a graph showing test results of examining the influence on grinding when the circular tube rotation speed is fixed at 80 m / min and the grindstone rotation speed is changed, (a) Cumulative grinding amount, (b) indicates the surface roughness Ry. As still another example of the above test, it is a graph showing a test result obtained by examining the influence of a change in feed speed on grinding, in which (a) shows a cumulative grinding amount and (b) shows a surface roughness Ry. As still another example of the above-described test, in order to investigate the influence of the strength of magnetic force on grinding, it is a cross-sectional view of the main part of the in-pipe grinding device when using a magnet with two magnets to increase the magnetic force. . As still another example of the above test, it is a graph showing the results of examining the influence of the strength of magnetic force on grinding, where (a) shows the cumulative grinding amount and (b) shows the surface roughness Ry. It is a graph which shows the grinding test result of the mirror surface finish using SD1000 and SD2000 as another example of the said test. It is a drawing substitute photograph which shows the said grinding test result. It is sectional drawing of the grinding processing apparatus using the electrolytic polishing method as the conventional grinding process. The grinding processing apparatus using the honing process method as the conventional grinding process is shown, (a) is principal part sectional drawing, (b) It is a principal part top view.

Explanation of symbols

1 Circular pipe 2 Grinding stone 3 Iron core (magnetic material)
5 Magnet (line of magnetic force generation)
6 Flexible cantilever shaft (grinding wheel drive unit)
8 Motor (Wheel driving unit)
9 Driven wheel (circular tube drive)
10 Whetstone stabilization cable (stabilization part)
11 Driving wheel (circular pipe drive)
12 Motor (circular tube drive unit)

Claims (11)

An outer diameter is set smaller than the inner diameter of the circular tube, a magnetic body is provided inside, a grindstone for grinding the inner surface of the circular tube by rotation,
A grindstone driving unit for rotationally driving the grindstone,
A circular tube driving unit for rotationally driving the circular tube;
It has a magnetic force generator that is movable in the axial direction of the circular tube at a position facing the grindstone and the circular tube, and generates a magnetic force line so as to generate an attractive force to the magnetic body. In-pipe grinding apparatus characterized by the above.   The in-pipe grinding apparatus according to claim 1, further comprising a stabilizing portion for stabilizing the movement of the grindstone.   The in-pipe grinding apparatus according to claim 1, further comprising a magnetic force movement control unit for moving the magnetic force generation unit.   The in-pipe grinding apparatus according to any one of claims 1 to 3, wherein the magnetic force generator is a permanent magnet.   5. The in-pipe grinding apparatus according to claim 1, wherein the grindstone driving unit and the circular tube driving unit are set so as to rotate the grindstone and the circular tube in directions opposite to each other. .   The in-pipe grinding apparatus according to any one of claims 1 to 5, wherein the grindstone driving unit includes a flexible cantilever rotating shaft that can transmit a rotational driving force even when the grindstone is bent.   The said circular pipe is provided with the welding trace which bent the board into the circular pipe shape by bending, and welded between each board adjacent to each other, The one of Claim 1 thru | or 6 characterized by the above-mentioned. In-pipe grinding machine. Set the grindstone for grinding the inner surface of the circular pipe by rotation so that the outer diameter of the grindstone is smaller than the inner diameter of the circular pipe,
The grindstone and the circular tube are respectively rotated while the outer peripheral surface of the grindstone is in contact with the inner peripheral surface of the circular tube,
While rotating the grindstone, move in the circular tube in the axial direction of the circular tube,
An in-pipe grinding method comprising pressing the circular tube while rotating and moving the grindstone.   9. The in-pipe grinding method according to claim 8, wherein when the grindstone and the circular pipe are respectively rotated, the grindstone and the circular pipe are set to rotate in directions opposite to each other. A magnetic material is provided inside the grindstone,
Further, a magnetic field line is generated so as to be movable in the axial direction of the circular tube at a position facing the grindstone and the circular tube, and to generate an attractive force to the magnetic body, so that the grindstone is The in-pipe grinding method according to claim 8 or 9, wherein the pipe is pressed against the pipe.   The in-pipe grinding method according to any one of claims 8 to 10, wherein the grindstone is rotationally driven through a flexible cantilever shaft capable of transmitting a rotational driving force even if the grindstone is bent.