Rotary joint, polishing device, cutting device, and powder dust removal method

Abstract

To inhibit failure caused by power dust mixing into a fluid in a rotary part of a rotary joint.SOLUTION: A rotary joint 70 circulates a fluid between a rotary part 80 which rotates and a non-rotary part 90 which does not rotate and includes: a change part 8b which is provided at the rotary part 80 and where a fluid flow direction is changed; and a jet port 8h which is provided at the rotary part 80 and jets a sub fluid for removing powder dust to the change part 8b.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a rotary joint, a grinding and cutting device, and a dust removal method. [Background technology]

[0002] As one type of joint having a fluid passage therein, a rotary joint in which a fluid flows between a rotating part and a non-rotating part is known. If dust is mixed in the fluid flowing through the rotary joint, there is a risk of malfunction due to the dust. In response to this, techniques have been proposed for processing dust that has become mixed in with the fluid flowing inside the rotary joint. For example, providing a fluid passage for sucking dust in the non-rotating part of the rotary joint has been considered (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-287173 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a rotary joint in which a fluid passage for suctioning dust is provided in the non-rotating part as described above, dust mixed in the fluid flowing inside the rotating part cannot be processed, and therefore problems caused by dust in the rotating part cannot be solved. For example, in a changing part in the rotating part where the flow direction of the fluid is changed, accumulation of dust is not suppressed, which may lead to problems such as pressure loss of the fluid and ignition of the accumulated dust. Therefore, there is room for improvement in preventing problems caused by dust mixed in the fluid in the rotating portion of the rotary joint.

[0005] The present invention has been devised in view of the above problems, and has as one of its objectives to suppress malfunctions caused by dust mixed in the fluid in the rotating part of a rotary joint. However, in addition to this objective, another objective of the present invention is to achieve actions and effects derived from the configurations shown in the "Mode for Carrying Out the Invention" described later, which are actions and effects that cannot be obtained with conventional technology. [Means for solving the problem]

[0006] The rotary joint disclosed herein has the following configurations (1) to (5). (1) A rotary joint that allows a fluid to flow between a rotating part that rotates and a non-rotating part that does not rotate, a change portion provided in the rotating portion and configured to change the flow direction of the fluid; an injection port provided in the rotating portion and configured to inject a secondary fluid for removing dust toward the changing portion; A rotary joint characterized in that (2) The injection port is drilled in a bolt fixed to the rotating portion. A rotary joint as described in (1). (3) a plurality of injection ports for injecting the secondary fluid radially toward the change portion; A rotary joint according to (1) or (2). (4) The fluid is sucked from the outside and introduced into the change section by an introduction section that is provided in the rotation section and that introduces the fluid into the change section so that the fluid turns at an obtuse angle in the change section. The rotary joint according to any one of (1) to (3) above. (5) The secondary fluid includes gas and liquid. The rotary joint according to any one of (1) to (4) above.

[0007] The polishing apparatus disclosed herein has the following configuration (6). (6) A grindstone for sharpening the cutting blade; a suction duct for sucking up abrasive powder generated by grinding the cutting blade with the grindstone; and a rotary joint according to any one of (1) to (5) to which the suction duct is connected and through which air containing the abrasive powder flows as the fluid. A polishing apparatus comprising:

[0008] The cutting device disclosed herein has the following configuration (7). (7) A polishing apparatus according to (6), and a cutting blade for cutting paper material. A cutting device characterized in that

[0009] The dust removal method disclosed herein has the following configuration (8). (8) A method for removing dust from a rotary joint in which a fluid flows between a rotating part and a non-rotating part, comprising the steps of: The method includes a step of injecting a secondary fluid for removing dust toward a change portion where the flow direction of the fluid is changed in the rotating portion. A dust removal method comprising the steps of: Effect of the Invention

[0010] According to the present invention, it is possible to suppress problems caused by dust mixed in the fluid in the rotating portion of the rotary joint. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a production line. [Diagram 2] FIG. 2 is a schematic diagram showing a cutting part of a production line. [Diagram 3] FIG. 4 is a perspective view showing a cutting device of a cutting part. [Figure 4] FIG. [Diagram 5] FIG.

[0012] Hereinafter, a rotary joint, a grinding device, a cutting device, and a dust removal method will be described as embodiments. The rotary joint of the present embodiment is a joint (also called a "rotary joint") that allows fluid to flow between a rotating part that rotates and a non-rotating part that does not rotate. In this embodiment, a rotary joint is provided in a toilet roll manufacturing line in which strip-shaped sanitary paper (paper material) is wound into a roll. This rotary joint is provided to remove dust, such as grinding powder and paper powder, generated when a blade (cutting blade) that cuts a log (paper material) into toilet rolls is ground with a grindstone.

[0013] Specifically, a cutting device that cuts logs into toilet rolls is provided with a blade for cutting the logs and a sharpening device for the blade. In addition to a grindstone for sharpening the blade, the sharpening device is provided with a suction duct for sucking in the abrasive powder generated by sharpening the blade with the grindstone, and a rotary joint to which the suction duct is connected. Air containing the abrasive powder flows into the rotary joint from the connected suction duct, and the air containing the abrasive powder flows inside. Since paper powder is generated when cutting the logs, the suction duct can suck in the paper powder in addition to the abrasive powder.

[0014] As described above, when air containing dust such as abrasive powder or paper powder is the fluid flowing through the inside of the rotary joint, there is a risk of problems occurring due to accumulation of dust in the fluid passages provided in the rotary joint. Therefore, the rotary joint of this embodiment is configured to inject a secondary fluid for removing dust in order to suppress the accumulation of dust. In addition, the dust removal method of this embodiment includes a step of injecting the secondary fluid for removing dust at the rotary joint.

[0015] I. One embodiment In the following embodiment, the configuration of the rotary joint is described in item [1], and the action and effect of the configuration of item [1] is described in item [2]. [1. Configuration] In this section [1], the basic configuration of a manufacturing line equipped with a rotary joint is outlined in subsection [1-1], and the main components related to the rotary joint are described in detail in subsection [1-2].

[0016] [1-1.Basic configuration] The rotary joint according to this embodiment is applied to a line for manufacturing toilet rolls (hereinafter referred to as the "manufacturing line"). As shown in Fig. 1, the production line 4 is provided with a log forming part 10 which forms a roll-shaped log 5 which is longer in the axial direction than the toilet roll 3, an adjusting part 20 which temporarily stores the logs 5 formed in the log forming part 10 and adjusts the timing of sending out the logs 5, and a cutting part 30 which cuts the logs 5 sent out from the adjusting part 20 into toilet rolls 3. Furthermore, the production line 4 is provided with a packaging part 40 which packages the toilet rolls 3 cut out by the cutting part 30 in fixed numbers, and a boxing part 50 which boxes the packages 9 of the toilet rolls 3 packaged by the packaging part 40.

[0017] Hereinafter, upstream and downstream are defined based on the order of each process performed in the production line 4. In the production line 4, a log forming part 10, an adjusting part 20, a cutting part 30, a packaging part 40, and a boxing part 50 are arranged in this order from upstream to downstream.

[0018] The log forming part 10 unwinds the base paper 11 (material) in a strip shape wider than the toilet roll 3 from a base roll 12 on which the base paper 11 is wound, and forms a log 5 by rewinding the base paper 11 with a winder 13. The log 5 is a paper material wound into a roll (i.e., a paper material) and has an axial length equal to the axial length of the base roll 12 and a diameter equal to the diameter of the toilet roll 3. In the winder 13, embossing or printing may be applied to the base paper 11. Furthermore, the base paper roll 12 may be a primary base paper (jumbo roll) on which a single layer (one ply) of base paper 11 made of one sheet of paper material is wound, or a secondary base paper on which multi-layer (two or more plies) base paper 11 made of multiple sheets of paper material is wound.

[0019] The winder 13 cuts the base paper 11 every time it is wound around a cylindrical core 5c (long core tube) by a predetermined length, thereby continuously forming the logs 5. More specifically, the base paper 11 is wound from the inner periphery (core 5c side) of the log 5 to the outer periphery (i.e., from the inside to the outside in the radial direction). Then, when a predetermined length of the base paper 11 is wound around the outer periphery of the core 5c, the base paper 11 is cut (divided) along a straight line along the width direction (direction perpendicular to the longitudinal direction) of the base paper 11, thereby forming the logs 5. Each log 5 has a winding end 5a glued (tail sealed) to the outer periphery in the gluing part 14, which is the final process of the log forming part 10, and is then sent to the downstream adjustment part 20.

[0020] The adjusting part 20 stores a plurality of logs 5 in an accumulator 21, and sequentially sends the logs 5 to the downstream cutting part 30. Here, an example of the adjusting part 20 that sends the logs 5 two at a time toward the cutting part 30 will be shown. The cutting part 30 cuts the logs 5 with a log saw 31. As a result, each log 5 is cut into a plurality of toilet rolls 3.

[0021] The packaging part 40 inserts, for example, four toilet rolls 3 (two rolls x two layers) as a set into the packaging bag 22 and seals the opening 19 of the packaging bag 22 to form a package 9. The box packing part 50 packs a plurality of (for example, four) packages 9 as one set into a cardboard box 23. Then, the packages 9 packed in the cardboard box 23 are shipped.

[0022] [1-2.Main part configuration] In the cutting part 30 in the above-mentioned manufacturing line 4, a log saw 31 would be sufficient if only cutting the logs 5, but as shown in Figure 3, a cutting device 39 is provided which includes not only the log saw 31 but also a grinding device 60. The log saw 31 is a basic device for cutting the log 5 (see FIG. 1), and is equipped with a blade 32 (cutting edge) for cutting the log 5. In contrast, the grinding device 60 is a device provided for maintaining good cutting performance of the log 5 by the blade 32, and is equipped with a grindstone 61 for grinding the blade 32. The grinding device 60 is provided with a rotary joint 70 for disposing of grinding powder generated by grinding the blade 32 by the grindstone 61. That is, the cutting device 39 includes the log saw 31 and the grinding device 60, and the grinding device 60 includes the rotary joint 70.

[0023] [1-2-1. Log saw] 2 and 3, the log saw 31 has a disk-shaped blade 32 with a sharp outer circumferential edge, and a support arm 33 that rotatably supports a center portion 36 of the blade 32. The blade 32 rotates relative to the support arm 33 about a rotation axis A2 that passes through the center portion 36 and extends in the thickness direction of the blade 32.

[0024] Meanwhile, the support arm 33 rotates at its base end opposite to the tip end to which the blade 32 is attached, around a rotation axis A3 extending along the rotation axis A2 of the blade 32. Therefore, it can be said that the blade 32 rotates about the rotation axis A2 and revolves around the rotation axis A3 of the support arm 33. For this reason, in the following description, the rotation axis A2 of the blade 32 is also referred to as the "rotation axis A2" and the rotation axis A3 of the blade 32 is also referred to as the "revolution axis A3."

[0025] In the cutting part 30 of this embodiment, the log 5 (see Figs. 1 and 2) is cut into a plurality of toilet rolls 3 by the rotating and revolving blade 32. The revolving blade 32 alternately comes into contact (cuts) and does not come into contact (separates) with the log 5 set in a cuttable position. In other words, in the process of making one revolution around the revolution axis A3, the blade 32 cuts (comes into contact with) the log 5 at the position where the log 5 is set, and separates from the log 5 at other positions. The number of blades 32 provided on the log saw 31 is usually up to two, but is not particularly limited. The log saw 31 may be provided with a plurality of blades 32 that revolve around the same revolution axis A3. Also, in the cutting part 30, a plurality of log saws 31 may be arranged side by side along the axial direction of the log 5.

[0026] The log 5 is fed into the log saw 31 with its axial direction aligned with the rotation axis A2 and revolution axis A3 of the blade 32, and is set on the track of the revolving blade 32. The log 5 is then cut (sliced) in the radial direction by the blade 32, which rotates and revolves as described above. Furthermore, the log 5 is transported in the axial direction by an amount corresponding to the axial length of the toilet roll 3 (product) while the blade 32 makes one revolution around the revolution axis A3. As a result, the log saw 31 cuts the log 5 at different axial positions with the blade 32 in sequence from one end 5b on the downstream side of the log 5 (hereinafter also referred to as the downstream end 5b) to the other end 5d on the upstream side (hereinafter also referred to as the upstream end 5d).

[0027] In the cutting part 30 of the present embodiment, the axial transport of the log 5 and cutting by the blade 32 are repeated as described above, so that a predetermined number of toilet rolls 3 are cut out from one log 5. Then, as shown in Fig. 1, once the set number of toilet rolls 3 have been cut out from the log 5, the toilet roll 3 is transported to the downstream packaging part 40, and the next log 5 is sent from the adjusting part 20 to the cutting part 30.

[0028] [1-2-2. Polishing device] In the log saw 31 for cutting the log 5 as described above, the blade 32 is sharpened by a sharpening device 60 (see FIG. 3) described next, so that the blade 32 maintains good cutting ability for the log 5. As shown in FIG. 3, the grinding device 60 is attached to the support arm 33 of the log saw 31 and rotates together with the blade 32 of the log saw 31 about the revolution axis A3.

[0029] The grinding device 60 is provided with a grindstone 61 for grinding the blade 32. The grindstone 61 is a member for grinding the cutting edge (outer peripheral end) of the blade 32. The grindstone 61 grinds the blade 32 by coming into contact with the blade 32 while rotating relatively to the blade 32. The grindstone 61 illustrated here is pivotally supported so as to be rotatable, and is driven by the rotating blade 32 by coming into contact with the blade 32. In addition, the grindstone 61 repeatedly comes into contact with and separates from the cutting edge of the blade 32 at predetermined intervals. The grindstone 61 may be constantly in contact with the cutting edge of the blade 32, and the blade 32 may be continuously ground, instead of being intermittently ground by the grindstone in this manner. Oil is sprayed onto the blade 32 to suppress frictional heat generated by grinding with the grindstone 61 and ensure grinding properties.

[0030] The polishing device 60 is also provided with a suction duct 62 and a rotary joint 70 to which the suction duct 62 is connected. The suction duct 62 is a duct that sucks in grinding powder generated when the blade 32 is ground by the grindstone 61. The suction duct 62 has an upstream end 6a (one end) that is an end to which the powder is sucked, connected to the vicinity of the grindstone 61, and a downstream end 6b (the other end) that is an end to which the powder is discharged, connected to the rotary joint 70. Air containing grinding powder generated when the blade 32 is ground by the grindstone 61 (hereinafter referred to as "dusty air") flows from the upstream end 6a to the downstream end 6b of the suction duct 62, and then flows into the rotary joint 70, becoming a fluid that flows inside the rotary joint 70.

[0031] In addition, the grinding device 60 illustrated here is provided with a pair of grindstones 61, one of which grinds one side of the cutting edge of the blade 32 (one side in the direction along the rotation axis A2), and the other grindstone 61 grinds the other side of the cutting edge of the blade 32 (the other side in the direction along the rotation axis A2). The pair of grindstones 61 grind the double-edged blade 32. Moreover, the suction duct 62 illustrated here is provided for each grinding wheel 61. That is, a pair of suction ducts 62 are provided, and each suction duct 62 is connected to a rotary joint 70.

[0032] [1-2-3. Rotary joint] The rotary joint 70 is a joint for discharging dust air supplied from the suction duct 62 of the grinding device 60 that revolves (rotates) together with the log saw 31 to a fixed structure. As shown in FIG. 4, this rotary joint 70 is provided with a rotating part 80 that rotates around the revolution axis A3, a non-rotating part 90 that is fixed and does not rotate, and a rotating part 7 that supports the rotating part 80 so that it can freely rotate relative to the non-rotating part 90.

[0033] A main body 7a incorporating a bearing is fixed to the rotating component 7, and a rotating shaft 7b is provided which is rotatably supported relative to the main body 7a. A rotating part 80 is attached to the rotating shaft 7b, and a non-rotating part 90 is attached between the rotating part 80 and the main body 7a. That is, the rotating part 80 is attached to the tip side of the rotating shaft 7b, and the base end side of the rotating shaft 7b is inserted into the non-rotating part 90. The downstream end 6b of the suction duct 62 is connected to the rotating part 80, and dusty air flows in at the rotary joint 70. This dusty air flows from inside the rotating part 80 to inside the non-rotating part 90, which does not rotate, and is discharged from the non-rotating part 90 to the outside of the system.

[0034] The rotating portion 80 is provided with a bracket 81 for mounting to the support arm 33 of the log saw 31, and a rotating block 82 to which the downstream end 6b of the suction duct 62 is attached. The bracket 81 is fixed to the tip of the rotating shaft 7b. A rotating block 82 is disposed on the base end side of the rotating shaft 7b relative to the bracket 81, and the rotating block 82 is fixed to the bracket 81. In this manner, the bracket 81 and the rotating block 82 are connected to rotate integrally with the rotating shaft 7b.

[0035] The non-rotating portion 90 is provided with a suction wheel 92 fixed integrally to a fixed block 91 . The components of the rotating section 80 and the non-rotating section 90 are arranged in the following order from the tip end side to the base end side of the rotating shaft 7b: bracket 81, rotating block 82, fixed block 91, and suction wheel 92. In addition, the suction wheel 92 is connected to a suction hose 8 that draws dusty air out of the system.

[0036] The bracket 81 is a member forming part of the structure that connects the rotating block 82 to the support arm 33 of the log saw 31. Here, a plate-shaped bracket 81 extending along a plane that intersects with the rotation axes A2, A3 is shown as an example. The rotating block 82, which will be described next, is fixed to the bracket 81 with a bolt 8d inserted into a bolt hole 8i provided in the rotating block 82. The rotating block 82 has a flow passage 2 therein for the dusty air flowing in from the suction duct 62 .

[0037] The dusty air that has flowed through the flow passage 2 of the rotating block 82 passes through the inside of the fixed block 91, flows through the inside of the suction wheel 92, and is discharged outside the system through the suction hose 8. The opening through which dusty air flows out from the rotating block 82 and the opening through which dusty air flows into the fixed block 91 are shaped to communicate with each other regardless of the rotation phase of the rotating block 82 relative to the fixed block 91. Fig. 4 shows an example of an opening through which dusty air flows into the fixed block 91, extending in the circumferential direction based on the revolution axis A3.

[0038] The configuration of the rotation block 82 will be described in detail below. 4, the downstream ends 6b of the suction ducts 62 are connected to the rotation block 82, and flow passages 2 for the dusty air flowing in from the suction ducts 62 are provided inside the rotation block 82 at this connection point. The rotation block 82 illustrated here is provided with flow passages 2 corresponding to the respective suction ducts 62 (one of which is not shown in FIG. 4).

[0039] In the flow passage 2 of the rotating block 82, the dusty air flows through the upper flow passage 2a, the middle flow passage 2b, and the lower flow passage 2c in that order. The upper flow passage 2a and the lower flow passage 2c are straight flow passages. In contrast, the middle flow passage 2b is a flow passage in which the flow direction of the dusty air changes from the upper flow passage 2a to the lower flow passage 2c. That is, the rotating block 82 has an inlet portion 8a that is a portion surrounding the upper flow path 2a, a change portion 8b that is a portion surrounding the middle flow path 2b, and an outlet portion 8c that is a portion surrounding the downstream flow path 2c. The inlet portion 8a, the change portion 8b, and the outlet portion 8c are portions in which the spaces that form the upper flow path 2a, the middle flow path 2b, and the downstream flow path 2c are provided as hollow spaces.

[0040] The upstream flow path 2a is arranged linearly in the rotating block 82 and inclined toward the tip side of the rotating shaft 7b (one side in the direction along the revolution axis A3) with respect to the radial direction (hereinafter simply referred to as the "radial direction") based on the revolution axis A3. From the viewpoint of ensuring a layout for connecting the suction duct 62, the direction in which the upstream flow path 2a extends is preferably a direction that is at an angle of 45° or more with respect to the revolution axis A3, more preferably a direction that is at an angle of 55° or more with respect to the revolution axis A3, and a suitable example is a direction that is at an angle of 65° with respect to the revolution axis A3. In addition, from the viewpoint of suppressing changes in the direction in which the dust air flows inside the rotating block 82, the direction in which the upstream flow path 2a extends is preferably a direction that forms an angle of less than 90° with respect to the revolution axis A3, more preferably a direction that forms an angle of 80° or less with respect to the revolution axis A3, and a suitable example is a direction that forms an angle of 65° with respect to the revolution axis A3.

[0041] The introduction section 8a surrounding the upstream flow path 2a includes a portion that protrudes radially in the rotating block 82, and is connected to the downstream end 6b of the suction duct 62 by being inserted into the opening of this protruding portion. The middle flow passage 2b is provided in a corner shape bent from the extension direction of the upper flow passage 2a to a direction parallel to the revolution axis A3. This bent structure changes the flow direction of the dusty air in the middle flow passage 2b, and the flow direction of the dusty air is changed at the change portion 8b surrounding the middle flow passage 2b.

[0042] The change section 8b, where the flow direction of the dusty air is changed, surrounds the middle flow passage 2b, which is bent from a direction extending at an angle toward the tip side of the rotary shaft 7b with respect to the radial direction (extension direction of the upper flow passage 2a) to a direction parallel to the revolution axis A3, as described above. For this reason, the introduction section 8a can be said to be a section that introduces the dusty air sucked in from outside the rotary joint 70 into the change section 8b so that the dusty air is bent at an obtuse angle in the change section 8b.

[0043] This modified portion 8b is provided with a bolt 8d that fixes the rotation block 82 to the bracket 81. Specifically, a head 8e (bolt head) of the bolt 8d is exposed in the space formed by the intermediate flow passage 2b surrounded by the modified portion 8b (or a space communicating with this space), and a shaft portion 8f of the bolt 8d is inserted into the bolt hole 8i in a direction extending parallel to the revolution axis A3, and a tip of the shaft portion 8f is screwed into the bracket 81.

[0044] Incidentally, the rotary joint 70 tends to require maintenance work, although the rotating portion 80, which rotates, is more difficult to maintain than the non-rotating portion 90, which does not rotate. In particular, in the middle flow passage 2b of the rotating section 80 surrounded by the change section 8b, dust in the dusty air is likely to accumulate because this is a section where the flow direction of the dusty air is changed, and there is a risk of malfunction due to the accumulation of dust. Examples of malfunctions here include pressure loss of the dusty air and ignition of the accumulated dust. In addition, dust in the dusty air mixed with abrasive powder together with the oil sprayed on the blade 32 may smolder due to the heat (or sparks) of the abrasive powder.

[0045] Therefore, the rotary joint 70 of this embodiment is provided with a structure for processing dust that may accumulate in the middle flow passage 2b. Specifically, the bolt 8d that fixes the rotating block 82 to the bracket 81 is provided with a structure for processing dust that may accumulate in the middle flow passage 2b. This bolt 8d is provided with a structure for blowing the secondary fluid onto the dust that may accumulate in the middle flow passage 2b. In other words, the existing bolt fixed to the rotating part 80 is used to process dust that may accumulate in the middle flow passage 2b.

[0046] In the present embodiment, the bolt 8d has a head 8e disposed at a position facing the wall surface surrounding the intermediate flow passage 2b in the modified portion 8b. 4 and 5, an internal passage 8g for a secondary fluid to be sprayed onto dust that may accumulate in the intermediate passage 2b is provided through the bolt 8d from the head 8e to the shaft 8f. In the internal passage 8g, the secondary fluid flows from the shaft 8f to the head 8e. An injection port 8h through which the secondary fluid is blown out from the internal passage 8g is drilled in the head 8e of the bolt 8d. The injection port 8h is an opening that jets the secondary fluid for removing dust toward the wall surface (changed portion 8b) surrounding the middle passage 2b. The injection port 8h that jets out the secondary fluid toward the changed portion 8b in this manner is provided facing in a radial direction centered on the direction in which the axial force of the bolt 8d acts. Here, three (multiple) injection ports 8h that jet the secondary fluid radially centered on the direction in which the axial force of the bolt 8d acts are arranged in the head 8e of the bolt 8d. That is, injection ports 8h facing three different directions (multiple directions) are formed in the head 8e of the bolt 8d. From the viewpoint of ensuring ease of processing for providing the internal passage 8g and the injection port 8h, it is preferable to use a hexagonal head bolt rather than a so-called cap screw bolt for the bolt 8d.

[0047] 4, the secondary fluid exemplified here is supplied from an internal passage 79 extending through the main body 7a and the rotating shaft 7b of the rotating component 7 and the bracket 81 to an external passage 89 leading to a connecting portion 8j for the bolt 8d, to an internal passage 8g of the bolt 8d. The connecting portion 8j for the bolt 8d is provided, for example, by being detachably screwed onto the bolt 8d, and is provided so as to be separable from the bolt 8d. In addition, in Fig. 4, the structure surrounding the internal passage 79 and the external passage 89 is illustrated as an integrated unit for convenience, but in the structure surrounding these passages 79, 89, at least the part of the main body 7a is provided separately from the other parts because the main body 7a does not rotate, whereas other parts such as the rotating shaft 7b and the bracket 81 rotate. Also, the groove portion 79a shown in Fig. 4 is a groove-shaped part that serves as a part of the internal passage 79, and is recessed into the outer circumferential surface of the rotating shaft 7b over the entire circumference around the rotation axis A3. In this way, the groove portion 79a that exists over the entire circumference in the rotation direction of the rotating shaft 7b allows the internal passage 79 in the main body 7a to communicate with the internal passage 79 in the rotating part 7b, regardless of the rotation phase of the rotating part 7b relative to the main body 7a.

[0048] The secondary fluid may be constantly injected from the injection port 8h, or may be injected periodically using a timer, etc. Using the timer, it is possible to set the injection time of the secondary fluid and the number of times the injection of the secondary fluid is stopped (the number of cut-offs). In addition, the downstream passage 2c is provided linearly in a direction extending parallel to the revolution axis A3. An opening communicating with the interior of the fixed block 91 is provided in the outlet section 8c surrounding the downstream passage 2c, and the dusty air led out from this opening flows into the non-rotating section 90.

[0049] A dust removal method is carried out in the above-described rotary joint 70. This dust removal method is a dust removal method for a rotary joint that circulates dusty air between the rotating part 80 and the non-rotating part 90, and includes an injection step of injecting a secondary fluid from an injection port 8h. In this injection step, the secondary fluid for removing dust is injected toward a change part 8b where the flow direction of the dusty air is changed in the rotating part 80.

[0050] [2. Actions and Effects] According to the rotary joint 70, the grinding device 60, the cutting device 39, and the dust removal method configured as described above, the following actions and effects (1) to (7) can be obtained. (1) The rotating part 80 of the rotary joint 70 is provided with an injection port 8h that injects a secondary fluid for removing dust toward the change part 8b where the flow direction of the dusty air is changed. As a result, the secondary fluid injected from the injection port 8h can blow away dust that may accumulate in the middle flow path 2b surrounded by the change part 8b. This makes it possible to suppress pressure loss of the dusty air flowing through the middle flow path 2b, and to prevent ignition of the dust accumulated in the middle flow path 2b. Therefore, in the rotating part 80 of the rotary joint 70, malfunctions caused by dust mixed in the dusty air can be suppressed. The above-mentioned functions and effects can also be obtained by the dust removal method of this embodiment.

[0051] (2) The injection port 8h is drilled into the bolt 8d fixed to the rotating portion 80, and therefore can be easily attached to an existing rotary joint 70 at a later date. Since this injection port 8h is drilled into a bolt that fixes the rotating block 82 to the bracket 81 in the rotating portion 80, an increase in the number of parts of the rotary joint 70 can also be suppressed.

[0052] (3) The rotary joint 70 of the present embodiment is provided with three (a plurality of) injection ports 8h that inject the secondary fluid radially, which contributes to reliable removal of dust that may accumulate in the intermediate flow passage 2b. These three injection ports 8h are provided in the head 8e of the bolt 8d. This makes it easy to form the three injection ports 8h facing in different directions. Although it is difficult to adjust the final rotation position when fastening the bolt 8d, if the injection ports 8h facing in three directions are formed in the head 8e of the bolt 8d, the secondary fluid is injected over a wide range regardless of the final rotation position of the bolt 8d, and dust that may accumulate in the middle passage 2b can be reliably removed.

[0053] (4) In a structure provided with an introduction section that introduces dusty air sucked in from the outside of the rotary joint into the modified section so that the dusty air turns at a right angle or an acute angle at the modified section, dust from the dusty air is likely to collide with the wall surface of the modified section, and dust is likely to accumulate. In contrast, introduction section 8a of the present embodiment introduces dusty air into modified section 8b so that the dusty air turns at an obtuse angle at modified section 8b, and therefore the dusty air is less likely to collide with the wall surface of modified section 8b, further suppressing dust accumulation. (5) Since the secondary fluid sprayed from the nozzle 8h is compressed air, the accumulation of dust can be suppressed by the secondary fluid, which is easier to process, compared to a configuration in which a liquid or granular material (solid) is sprayed from the nozzle 8h.

[0054] (6) The grinding device 60 provided with the rotary joint 70 is provided with a grindstone 61 for grinding the blade 32, as well as a suction duct 62 for sucking in grinding powder generated when the blade 32 is ground by the grindstone 61, and this suction duct 62 is connected to the rotary joint 70. Therefore, in the grinding device 60 for grinding the blade 32, grinding powder such as iron powder generated when the blade 32 is ground can be sucked and removed, and dust including grinding powder can be prevented from accumulating at the change portion 8b of the rotary joint 70. In this way, dust that may be ignited by sparks generated when the blade 32 is ground by the grindstone 61 can be removed, improving fire resistance.

[0055] (7) The cutting device 39 is not only provided with the log saw 31 equipped with the blade 32 that cuts the log 5, but also with the grinding device 60 and the rotary joint 70. Therefore, even if the grinding powder generated from the grindstone 61 of the grinding device 60 and the paper powder generated when the log 5 is cut by the blade 32 are mixed into the dusty air as dust, the dust such as the grinding powder and the paper powder can be prevented from accumulating at the change portion 8b of the rotary joint 70. In addition, paper dust generated when the blade 32 cuts the log 5 is sucked through the suction duct 62, thereby preventing the adhesion of paper dust to the cut log 5 and the toilet roll 3 from which the log 5 is cut. Also, the blade 32 of the cutting device 39 is ground by the grindstone 61 of the grinding device 60, improving the cutting performance of the log 5 and helping to prevent the generation of paper dust. This also helps to prevent the adhesion of paper dust to the toilet roll 3.

[0056] [II. Modifications] The above-described embodiment is merely an example, and is not intended to exclude various modifications and application of techniques not explicitly stated in the embodiment. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the embodiment. In addition, the configurations can be selected as necessary, and can be combined appropriately.

[0057] For example, the number of secondary fluid injection ports is not limited to three (multiple), and only one (single) may be provided. Furthermore, the secondary fluid injection port is not limited to a structure in which it is drilled in the bolt, and may be provided at least in the rotating part of the rotary joint. One example of such an injection port is one in which an opening for the secondary fluid is provided in a through hole extending from the bracket to the rotating block. That is, a secondary fluid injection path may be formed in the rotating part separately from the bolt.

[0058] Moreover, the secondary fluid injected from the injection port is not limited to a gas such as compressed air, but may be a liquid. That is, any fluid may be used as the secondary fluid as long as it is a fluid that can be mixed into the flow path of the dusty air. An example of the secondary fluid is a liquid for preventing or extinguishing the ignition of accumulated dust, and another example is a non-flammable gas for preventing the ignition of accumulated dust. Furthermore, gas and liquid may be used in combination as the secondary fluid. When a liquid is used as the secondary fluid, dust can be reliably removed and washed, or the flow path can be moistened, which contributes to reliably eliminating problems caused by dust mixed in the dusty air. When a gas and a liquid are used in combination as the secondary fluid, problems caused by dust mixed in the dusty air can be further eliminated.

[0059] Alternatively, the introduction portion of the rotating block is not limited to a form in which dust air sucked in from outside the rotary joint is introduced into the change portion so that the dust air bends at an obtuse angle in the change portion, but may be a form in which dust air sucked in from outside the rotary joint is introduced into the change portion so that the dust air bends at a right angle or an acute angle in the change portion. The grinding apparatus is not limited to being incorporated in the cutting apparatus, and various other installation configurations may be adopted. The rotary joint is also not limited to being incorporated in the grinding apparatus, and various other installation configurations may be adopted.

[0060] In addition, the product manufactured by the manufacturing line to which the rotary joint is attached is not limited to toilet rolls, but may be kitchen paper in which strip-shaped sanitary paper (paper material) is wound into a roll, or may be a tissue paper bundle or kitchen paper bundle in which sheet-shaped sanitary paper (paper material) is stacked. In other words, the object to be cut by the cutting device to which the rotary joint is attached may be a log to be cut into a roll of kitchen paper, or a long laminate to be cut into a tissue paper bundle or kitchen paper bundle. Furthermore, the rotary joint may be attached to a line (i.e., a manufacturing line) that manufactures any product, not limited to paper products such as toilet rolls and kitchen paper, and the rotary joint may be provided in a cutting device that cuts and separates semi-finished products of various products. [Explanation of symbols]

[0061] 2 Distribution path 2a Upstream channel 2b Middle flow path 2c downstream path 3. Toilet roll 4 Production Line 5 Logs 5a End of winding 5b One end 5c Core 5d Other end 7 Rotating Parts 7a Main body 7b Rotating shaft 8 Suction hose 9 Package 10 Log formation part 11 Base paper (materials) 12 Raw material roll 13 Winder 14 Gluing part 19 Opening 20 Adjustment Part 21 Accumulator 22 Packaging bag 23 Cardboard Box 30 Cutting Part 31 Log saw 32 Blade (Cutting blade) 33 Support Arm 36 Center 39 Cutting device 40 Packaging Part 50 Packing Part 60 Polishing equipment 61 Grindstone 62 Suction duct 63 Tank (storage section) 6a Upstream end (one end) 6b Downstream end (other end) 70 Rotary joint 79 Internal passage 80 Rotating section 81 Bracket 82 Rotating Block 8a Introduction 8b Changes 8c Derivation part 8d Bolt 8e head 8f shaft part 8g internal passage 8h injection port 8i Bolt hole 8j Connection 89 Exterior Passage 90 Non-rotating part 91 Fixed Block 92 Suction Wheel A2 Rotation axis (rotation axis) A3 revolution axis (rotation axis)

Claims

1. A rotary joint that allows a fluid to flow between a rotating part that rotates and a non-rotating part that does not rotate, a change portion provided in the rotating portion and configured to change the flow direction of the fluid; an injection port provided in the rotating portion and configured to inject a secondary fluid for removing dust toward the changing portion; A rotary joint characterized in that

2. The injection port is drilled in a bolt fixed to the rotating portion.

2. A rotary joint according to claim 1.

3. a plurality of injection ports for injecting the secondary fluid radially toward the change portion; 2. A rotary joint according to claim 1.

4. The fluid is sucked from the outside and introduced into the change section by an introduction section that is provided in the rotation section and that introduces the fluid into the change section so that the fluid turns at an obtuse angle in the change section.

2. A rotary joint according to claim 1.

5. The secondary fluid includes gas and liquid.

2. A rotary joint according to claim 1.

6. A grindstone for sharpening the cutting blade; a suction duct for sucking up abrasive powder generated by grinding the cutting blade with the grindstone; and a rotary joint according to any one of claims 1 to 5, to which the suction duct is connected and which circulates air containing the abrasive powder as the fluid. A polishing apparatus comprising:

7. A polishing apparatus according to claim 6, and a cutting blade for cutting paper material. A cutting device characterized in that

8. A method for removing dust from a rotary joint in which a fluid flows between a rotating part and a non-rotating part, comprising the steps of: The method includes a step of injecting a secondary fluid for removing dust toward a change portion where the flow direction of the fluid is changed in the rotating portion. A dust removal method comprising the steps of:

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