JP3294165B2 - Existing pipe cutting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an existing pipe cutting apparatus which is used, for example, for cutting and removing a part of an existing water pipe in a sealed housing in a water-free state. A cutting unit provided with a cutting tool for cutting the peripheral wall along the circumferential direction, a guide support unit that rotatably supports the cutting unit around a pipe axis, and a driving unit that drives and rotates the cutting unit. The cutting unit includes a screw-type feed mechanism that moves the cutting bite in the pipe diameter direction, and an engagement portion provided on a fixed portion beside a rotation path of the cutting unit. The present invention relates to an existing pipe cutting device in which a mechanism is provided with a passive rotating body that imparts rotation corresponding to a unit feed amount.

[0002]

2. Description of the Related Art In a conventional existing pipe cutting device, the engaging portion is formed of a plate-shaped engaging piece projecting toward a rotation axis of the cutting unit (the pipe axis of the existing pipe). The passive rotator is constituted by a passive gear, and the passive gear is provided on the screw shaft of the screw-type feed mechanism in an integrally rotating state,
The rotation angle of the passive gear between the time when one tooth portion of the passive gear driven and rotated integrally with the cutting unit is engaged with the engagement piece and is disengaged is determined by the unit feed amount of the screw type feed mechanism. (For example, see Japanese Patent Application Laid-Open No. 3-14996).

[0003]

In the conventional pipe cutting device, the passive gear is fixed to the screw shaft of the screw type feed mechanism, and the unit rotation angle of the passive gear is set to the unit feed amount of the screw type feed mechanism. In order to change the unit feed amount of the screw-type feed mechanism to a small value according to the cutting conditions such as the material of the existing pipe and the cutting performance of the cutting tool,
It is necessary to reduce the pitch of the teeth of the passive gear and to reduce the protrusion of the teeth in the radius direction of rotation.
However, the smaller the unit feed amount of the screw-type feed mechanism is set, the smaller the engagement allowance between the tooth portion of the passive gear and the engagement piece on the fixed portion side becomes. When an assembly error occurs in a part, a cutting unit, or the like, a situation may occur in which the teeth of the passive gear and the engaging piece are engaged, or the teeth of the passive gear do not engage with the engaging piece. Easier to do. Therefore, high accuracy is required not only for the processing accuracy of the components that make up the existing pipe cutting device such as the guide support section and the cutting unit, but also for the assembling accuracy of the cutting device at the construction site. There has been a problem that it leads to a reduction in the efficiency of assembly and assembly work.

The present invention has been made in view of the above-mentioned circumstances, and a main problem thereof is to improve the structure of a rotary transmission system from the passive rotating body to a screw-type feed mechanism by using a screw type. An existing pipe cutting device that can easily change the unit feed amount of the feed mechanism to the feed amount according to the cutting conditions, etc., can be advantageously manufactured in terms of assembly work efficiency and construction cost at the construction site. On the point.

[0005]

According to a first aspect of the present invention, there is provided an existing pipe cutting apparatus comprising: a cutting unit having a cutting tool for cutting a peripheral wall of an existing pipe along a circumferential direction;
A guide support unit that rotatably supports the cutting unit around the pipe axis; and a driving unit that drives and rotates the cutting unit. The cutting unit includes a screw type that moves the cutting tool in the pipe diameter direction. A passive rotator that applies rotation corresponding to a unit feed amount to the screw-type feed mechanism by engaging a feed mechanism and an engagement portion provided on a fixed portion beside the rotation path of the cutting unit is provided. An existing pipe cutting device, wherein a speed reduction mechanism is interposed in a rotation transmission system from the passive rotating body to the screw shaft of the screw-type feed mechanism. According to the above-mentioned characteristic configuration, when the passive rotator that is driven and rotated integrally with the cutting unit rotates while engaging with the engaging portion provided on the fixed portion beside the rotation path, the rotation of the passive rotator is performed. Since the force is transmitted to the screw shaft of the screw-type feed mechanism via the speed reduction mechanism, the rotation angle of the screw shaft becomes smaller than the rotation angle of the passive rotary body by the reduction ratio of the speed reduction mechanism. Therefore, when changing the unit feed amount of the screw type feed mechanism to a small value in accordance with the cutting conditions such as the material of the existing pipe and the cutting performance of the cutting tool, the rotational radius direction between the passive rotary body and the engaging portion is changed. Even if the engagement allowance is increased and the rotation angle per rotation of the passive rotator is set large, the unit feed amount of the screw type feed mechanism can be reduced. Moreover, even if an error occurs in the margin of engagement between the passive rotating body and the engaging portion in the radial direction of rotation of the passive rotating body, the reduction ratio of the reduction mechanism of the reduction mechanism is smaller than that of a conventional existing pipe cutting device. Since the fluctuation width of the rotation angle of the screw shaft is reduced by the amount, the accuracy of the unit feed amount of the screw feed mechanism can be improved. Therefore, while freely setting the engaging portion on the fixed portion side and the passive rotating body to a dimensional relationship that does not cause a biting or non-engaging state due to an assembly error, the unit of the screw type feed mechanism is The feed amount can be easily set to the feed amount according to the cutting conditions, and the variation in the rotation angle of the screw shaft due to the assembly error can be reduced. An existing pipe cutting device that can easily change the amount to a feed amount according to the cutting conditions can be advantageously manufactured in terms of an assembly work surface at a construction site and a construction cost.

The existing pipe cutting device according to a second aspect of the present invention is characterized in that the speed reduction mechanism comprises a worm interlocked with the passive rotating body and a worm wheel interlocked with a screw shaft of the screw type feed mechanism. It is in the point. According to the above-mentioned characteristic configuration, the speed reduction mechanism is composed of a worm and a worm wheel. A deceleration ratio can be secured. In addition, even if an external force in the reverse rotation direction acts on the screw shaft of the screw type feed mechanism due to a cutting reaction force, vibration, or the like, passive rotation from the screw shaft side between the worm and the worm wheel constituting the speed reduction mechanism. Since the reverse rotation transmission to the body is prevented, it is possible to prevent the feed amount of the cutting bite from decreasing due to the reverse rotation of the screw shaft.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment FIGS. 1 to 6 show a first embodiment of an existing pipe cutting device A of the present invention, which is provided with a cutting tool 2 for cutting a peripheral wall 1A of an existing pipe 1 along a circumferential direction. It comprises a cutting unit 3, a guide support unit 4 for rotatably supporting the cutting unit 3 around the pipe axis X of the existing pipe 1, and a driving unit 5 for driving and rotating the cutting unit 3. In the cutting unit 3, the cutting tool 2 is attached to the existing pipe 1.
The unit feed amount on the screw shaft 8 of the screw type feed mechanism 6 by the engagement of the screw type feed mechanism 6 for moving in the pipe diameter direction and the engaging part 7 provided on the fixed part beside the rotation path of the cutting unit 3. And a passive rotator 9 for imparting rotation corresponding to.
Furthermore, a rotation transmission system from the passive rotating body 9 to the screw shaft 8 of the screw type feed mechanism 6, that is, a speed reduction mechanism 10 is interposed between the passive rotating body 9 and the screw shaft 8.

As shown in FIGS. 6 and 7, the existing pipe cutting device A cuts and removes a part of the existing pipe 1 in a sealed housing 11 and then removes the cut and removed pipe section 12.
Is used in the existing pipe replacement device B for mounting the replacement pipe section 13 at a location corresponding to the above. The housing 11 includes a lower housing 14 having an upward opening through which the existing pipe 1 is penetrated so as to surround a portion corresponding to the removal pipe section, and an upper housing 15 detachably attached to the opening of the lower housing 14 in a sealed state. It consists of: The existing pipe cutting device A is provided in the lower housing 14 in order to cut both ends of the existing pipe 1 at locations corresponding to the removal pipe section, and as shown in FIG.
In addition, a seal flange member 16 fitted externally to the exchange pipe portion 13 so as to be relatively movable in the pipe axis direction from the outside of the housing 11 to the joint portion between the existing pipe 1 and the exchange pipe portion 13 is slid. The upper housing 15 is provided with a holding / elevating device 18 which moves up and down while holding the removal pipe section 12 and the exchange pipe section 13 separately.

As shown in FIG. 8, the feeder mechanism 17 includes a blade member 19 erected on the seal flange member 16,
A feed screw 20 screwed into a screw hole provided in the blade member 19, a stopper plate 21 erected on the exchange pipe portion 13 so as to be able to contact one end of the feed screw 20, and a feed screw 20
And a rotating operation body 22 for engaging and rotating the other end of the rotating operation body.
Are reciprocally movable and rotatably held by a guide seal member 23 provided on a side wall of the lower housing 14 in a state where the distal end thereof protrudes outside.
Of these, by rotating the square shaft portion formed at the portion protruding to the outside, the seal flange member 16 of the replacement pipe portion 13 that is attached to a portion corresponding to the removal tube portion instead of the resection tube portion 12 is installed. The joint can be slid to the joint between the pipe 1 and the exchange pipe section 13. When the seal flange member 16 is fixed in a state of straddling the existing pipe 1 and the exchange pipe section 13, the gap between the inner peripheral surface of the seal flange member 16 and the outer peripheral faces of the existing pipe 1 and the exchange pipe section 13 is obtained. The elastic seal material 16A interposed between the inner peripheral surface of the seal flange member 16 and the outer peripheral surface of the existing pipe 1, the inner peripheral surface of the seal flange member 16 and the outer periphery of the exchange pipe portion 13 It can be sealed from the outside by the elastic sealing material 16B interposed between the surface.

As shown in FIG. 1, the lower housing 1
4 is formed into two parts, a first member 14A located above the existing pipe 1 and a second member 14B located below the existing pipe 1, in order to sandwich the existing pipe 1 from above and below. A semicircular notch 24A for forming a pair of through-holes 24 for penetrating the existing pipe 1 is formed at a connecting portion of each of the two members 14A and 14B. Each of the annular gaps formed between each through hole 24 of the lower housing 14 and the outer peripheral surface of the peripheral wall 1A of the existing pipe 1 is closed by a closing ring 25 fitted externally to the existing pipe 1. Yes,
A tubular portion 25A of the closing ring 25 is externally fixed to the outer peripheral surface of the peripheral wall 1A of the existing pipe 1 via a first packing 26, and a flange portion 25B integrally formed on one end side of the tubular portion 25A is provided. It is connected and fixed to the outer surface of the side wall of the lower housing 14 via the second packing 27. Further, on the other end side of the inner peripheral surface of the cylindrical portion 25A of the closing ring 25, a tapered surface having a larger diameter toward the opening side is formed.
Between the tapered surface and the outer peripheral surface of the peripheral wall 1A of the existing pipe 1,
A centering ring 28 having a tapered surface used for centering the closing ring 25 with respect to the existing pipe 1 is inserted and mounted. The closing ring 25 and the centering ring 2
Numerals 8 are respectively formed in two parts so as to sandwich the existing pipe 1 from above and below.

As shown in FIG. 1, the existing pipe cutting device A
The guide support portion 4 constituting the
A cylindrical pedestal 29, which is bolted and fixed to the inner surface of the side wall of the lower housing 14 together with the flange portion 25B,
9, a ring-shaped guide disk 30 which is concentrically fixed to the free end side and guides the cutting unit 3 relatively rotatably around the pipe axis X of the existing pipe 1. The guide support portion 4 is disposed so that the existing pipe 1 is inserted into a through hole 31 formed in the center of the guide disk 30 and a through hole 32 of the pedestal 29.

As shown in FIG. 1, the cutting unit 3
Is a ring-shaped sprocket wheel 34 provided on one side with a concave portion 33 for receiving the guide disk 30 of the guide support portion 4, and the screw type provided at one circumferential position on the other side of the sprocket wheel 34. It comprises a feed mechanism 6 and the cutting tool 2 attached to a top member 35 of the screw type feed mechanism 6. The escape of the guide disk 30 from the recess 33 of the sprocket wheel 34 is regulated by a contact piece 36 detachably attached to one side surface of the sprocket wheel 34. Also, a recess 33 and a contact piece 36 of the sprocket wheel 34,
A low friction material 37 made of synthetic resin or the like is interposed between the opposing surfaces of the guide disk 30 for the purpose of reducing friction. The guide support portion 4 and the sprocket wheel 34 of the cutting unit 3 are surrounded from the outside in the pipe diameter direction with respect to the peripheral wall 1A of the existing pipe 1. The sprocket wheel 3 is composed of a pair of divided guide support portions 4A divided into two.
4 is composed of a pair of split sprocket wheels 34A divided into two in the radial direction of the pipe, and the screw type feed mechanism 6 is attached to one of the split sprocket wheels 34A.

As shown in FIGS. 1 to 7, the screw type feed mechanism 6 includes a base 38 fixed to a sprocket wheel 34, and a fixing portion 35A to which a base end of the cutting bite 2 is detachably attached. And the screw shaft 8 which feeds and moves the top member 35 to the tube axis X side of the existing pipe 1. The top member 35 is mounted on the base 3.
In the dovetail groove 39 formed in 8, the external fitting is held so as to be relatively movable along the pipe radial direction of the existing pipe 1. The screw shaft 8
Is rotatably supported by a support member 40 fixed to the base 38, and a male screw portion 8A at one end thereof is screwed to a female screw portion 35B of the top member 35,
A worm wheel 41 interlocking with the screw shaft 8 is fixed to the other end of the screw shaft 8. Further, the support member 40
A worm 42 meshing with the worm wheel 41 is rotatably supported around an axis parallel to the rotation axis of the sprocket wheel 34. One end of the rotation shaft that rotates integrally with the worm 42 has (In this embodiment, 5
The star wheels 9 which are radially formed at equal intervals are fixed to the star pieces 9A, and the worm 42 is configured to interlock with the star wheels 9.

Incidentally, as shown in FIG.
The main blade portion 2A that cuts while cutting the peripheral wall 1A of the existing pipe 1 along the circumferential direction, and the chamfering blade portion 2B that chamfers the outer peripheral edge side of the cut surface of the remaining pipe portion 43 at the distal end portion. Is provided.

As shown in FIGS. 1, 6, and 7, the drive unit 5 is connected to an electric motor 44 mounted on an outer surface of a side wall of the lower housing 14, and is in a state of being operatively connected to an output shaft of the electric motor 44. And an endless chain 47 wound around a drive sprocket 46 fixed to the end of the output shaft 45 and a sprocket wheel 34 of the cutting unit 3. I have. That is, when the electric motor 44 is driven and rotated, the driving rotation is performed by the output shaft 45 and the driving sprocket 4.
The cutting unit 3 is transmitted to the sprocket wheel 34 via the endless chain 6 and the endless chain 47 so as to drive and rotate.

As shown in FIG. 4, the engaging portion 7 includes a pair of plate pieces disposed in the vicinity of a radially outer side of the sprocket wheel 34 of the cutting unit 3 along the rotation direction of the sprocket wheel 34. And a pedestal 49 fixedly bolted to a specific location on the inner surface of the side wall of the lower housing 14 as the fixing portion, and fixedly supporting the two plate pieces 48.
A part of the two plate pieces 48 is arranged so as to sequentially engage with the protruding pieces 9A of the star wheel 9 as the cutting unit 3 rotates. When one protruding piece 9A of the star wheel 9 engages with the first plate piece 48A on the upper side in the rotation direction with the driving rotation of the cutting unit 3, the protruding piece 9A and the first plate piece 48A Until the engagement is released by their relative movement, the star wheel 9 rotates to the normal rotation side, and the following protruding piece 9A of the one protruding piece 9A is rotated to the second plate piece 4 on the lower side in the rotation direction.
8B, the rotation of the star wheel 9 stops,
After the following protruding piece 9A and the second plate piece 48B are engaged, the star wheel 9 rotates to the normal rotation again until the engagement is released by their relative movement.

The angular velocity of the star wheel 9 during forward rotation is reduced via the worm 42 and the worm wheel 41, and the external thread 8A of the screw shaft 8 rotates at an angular velocity lower than the angular velocity of the star wheel 9. Wagon top member 3
5, the top member 35 moves along the dovetail groove 39 toward the pipe axis X of the existing pipe 1, and the cutting bit 2 is moved along the pipe axis of the existing pipe 1 accordingly. Move to the axis X side. The amount of double movement of the top member 35 toward the pipe axis X of the existing pipe 1 when the star wheel 9 rotates twice forward by sequentially engaging with both plate pieces 48 of the engagement portion 7 is described. The sum corresponds to the unit feed amount of the top member 35 of the screw type feed mechanism 6. In other words, the star wheel 9 rotates the screw shaft 8 of the screw type feed mechanism 6 by the engagement corresponding to the unit feed amount by the engagement of the engaging portion 7 provided in the vicinity of the cutting unit 3 with the two plate pieces 48. The deceleration mechanism 10 is constituted by the worm 42 linked to the star wheel 9 and the worm wheel 41 linked to the screw shaft 8 of the screw-type feed mechanism 6. Further, the unit feed amount of the top member 35 of the screw type feed mechanism 6 is a cutting depth by the main blade portion 2A of the cutting tool 2. When the cutting unit 3 is rotated in the reverse direction by rotating the electric motor 44 in the reverse direction, and the star wheel 9 is rotated in the reverse direction, the top member 35 moves to the opposite side to the tube axis X of the existing tube 1. Since the cutting tool 2 moves, the cutting tool 2 can be moved back to the opposite side of the existing pipe 1 from the pipe axis X side. Even if the other end of the rotation shaft of the worm 42 is forcibly rotated in the reverse direction, the cutting bit 2 can be returned to the opposite side of the existing pipe 1 from the pipe axis X side.

Next, with reference to FIGS. 9 to 13, a description will be given of a working process in the case where the existing pipe replacing apparatus B is used for replacing a part of an existing water pipe which is an example of the existing pipe 1. FIG. . As shown in FIG. 9, a pit for mounting the housing 11 on the existing pipe 1 buried underground is excavated,
For example, the existing pipe 1 including the gate valve 50 to be replaced is exposed. In this case, the gate valve 50 and a part of the existing pipe 1 connected to the gate valve 50 correspond to the removal pipe section 12. Hereinafter, description will be made in order. 1) The first member 14A and the second member 14B of the lower housing 14 are assembled to the existing pipe 1 in a state where the portion corresponding to the removal pipe portion of the existing pipe 1 is covered with the existing pipe 1, and the existing pipe 1 and the lower housing 14 are attached to each other. The closing ring 25 is assembled over the entire pipe 1, and the centering of the closing ring 25 with respect to the existing pipe 1 is performed by the centering ring 28. 2) Two sets of existing pipe cutting devices in which the guide support part 4 and the cutting unit 3 are assembled so that the cutting bit 2 of the cutting unit 3 is located at a predetermined cutting position with respect to the peripheral wall 1A of the existing pipe 1. A is fixed to the lower housing 14 together with the flange portion 25B of the closing ring 25 via the pedestal 29. 3) An endless chain 47 is wound around the driving sprocket 46 of the electric motor 44 and the sprocket wheel 34 of the cutting unit 3 and connected so as to transmit power. 4) The lifting rod 18A of the holding elevating device 18 provided in the upper housing 15 is lowered, and the removing pipe 12 is held by the holding attachment 18B. 5) The upper housing 1 is inserted into the opening of the lower housing 14.
When the inside of the housing 11 is hermetically sealed by hermetically mounting 5, the state shown in FIG. 10 is obtained. 6) The cutting unit 3 is driven to rotate forward by the electric motor 44 to rotate the cutting tool 2 in the circumferential direction of the peripheral wall 1A of the existing pipe 1, and the engaging portion 7 and the passive rotating body 9 associated therewith. The forward rotation of the star wheel 9 due to the engagement between the pair of plate pieces 48 and the projecting piece 9A of the star wheel 9,
The cutting tool 2 is fed and moved to the peripheral wall 1A side of the existing pipe 1 while the screw shaft 8 of the screw type feed mechanism 6 is rotated in the forward direction by the speed reduction mechanism 10 to cut the removal pipe section 12. At this time, the water flowing out of the cut portion of the existing pipe 1
When the inside is filled, no further outflow occurs, and the flow of water through the existing pipe 1 is maintained. That is, the removal pipe section 12 can be cut in a water-free state. 7) After the cutting of the removal pipe section 12 by the cutting tool 2 is completed, the cutting unit 3 is driven to rotate in the reverse direction by the electric motor 44 so that the cutting tool 2 circulates in the circumferential direction of the peripheral wall 1A of the existing pipe 1. With a pair of plate pieces 4
When the star wheel 9 rotates in reverse due to the engagement of the projection 8 with the protruding piece 9A of the star wheel 9, the cutting tool 2 is returned while the screw shaft 8 of the screw type feed mechanism 6 is rotated in the reverse direction by the speed reduction mechanism 10. When the cutting tool 2 is moved and the seal flange member 16 is slid to the seam portion between the existing pipe 1 and the replacement pipe section 13, the seal flange member 16 and the main blade 2A of the cutting tool 2 come into contact with each other. Move it away from the peripheral wall 1A of the existing pipe 1 to a position where it does not hit. 8) The lifting rod 18A of the holding lifting device 18 until the removing pipe part 12 is located in the inner region of the upper housing 15.
Is raised, and the lower shutter 14 is sealed with respect to the upper housing 15 by activating the shielding shutter 51 provided on the upper portion of the lower housing 14. The state shown in FIG. 9) Remove the upper housing 15 from the lower housing 14. In this state, even when the upper housing 15 is removed from the lower housing 14, the flow of water in the existing pipe 1 is maintained. That is, the uninterrupted water state can be continued. 10) After opening the upper housing 15 and removing the removing tube portion 12 held by the holding attachment 18B,
The holding pipe 18 is held by the holding attachment 18B with a new gate valve 50 and the exchange pipe section 13 provided with the seal flange members 16 at both ends thereof, and the upper housing 15 is hermetically attached to the opening of the lower housing 14 again.
To communicate the upper housing 15 and the lower housing 14. 11) When the elevating rod 18A of the holding elevating device 18 is lowered and the replacement pipe portion 13 held by the holding attachment 18B is positioned at a position corresponding to the removal pipe portion of the existing pipe 1, the state shown in FIG. 12) Feeder mechanism 17 from outside of housing 11
Is operated, the seal flange member 16 is slid to the joint between the existing pipe 1 and the replacement pipe section 13, and the state shown in FIG. 13 is obtained. 13) After removing the upper housing 15 from the lower housing 14, the existing pipe cutting device A is disassembled and the lower housing 14 is removed from the existing pipe 1. Through the above-described operation steps, the replacement of a part of the existing pipe 1 is completed without obstructing the flow of the fluid in the existing pipe 1, here, tap water.

[Second Embodiment] FIG. 14 shows another embodiment of the speed reduction mechanism 10 of the first embodiment.
Is a small-diameter bevel gear 5 linked to the star wheel 9.
2 and a large-diameter bevel gear 53 interlocking with the screw shaft 8 of the screw type feed mechanism 6. Specifically, a large-diameter bevel gear 53 interlocking with the screw shaft 8 is fastened to the other end of the screw shaft 8 of the screw-type feed mechanism 6, and a large-diameter bevel gear is attached to the support member 40. A small-diameter bevel gear 52 meshing with 53 is rotatably supported around an axis parallel to the rotation axis of the sprocket wheel 34. Also, at one end of a rotating shaft that rotates integrally with the small-diameter bevel gear 52,
The star wheel 9 is fixed. The other configuration is the same as that of the first embodiment. Components having the same configuration or the same function as the components described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

[Other Embodiments] In each of the above embodiments, when the cutting unit 3 is rotatably supported around the pipe axis X, the guide support unit 4 and the electric motor 44 of the drive unit 5 are both mounted on the lower housing 14. Although the existing pipe cutting device A to be fixed has been described, the existing pipe cutting device A is not limited to this, and the driving unit 5 is provided in the holding and lifting device 18 or the guide support unit 4. And the drive unit 5 are both held and lifted
May be provided. The screw-type feed mechanism 6 is not limited to the configuration described in each of the above embodiments, but includes a passive rotating body 9.
If a speed reduction mechanism 10 is interposed in the rotation transmission system of the screw type feed mechanism 6 to the screw shaft 8 so that the cutting tool 2 can be moved in the pipe diameter direction by the rotation of the passive rotary body 9. The structure can be appropriately changed. The reduction mechanism 10 may be a combination of a worm 42 and a worm wheel 41 or a small diameter bevel gear 5.
The combination is not limited to the combination of the large diameter bevel gear 53 and the large diameter bevel gear 53. For example, a combination of a small diameter sprocket wheel and a large diameter sprocket wheel and an endless chain wound around both sprocket wheels, or a small diameter pulley And a combination of a large-diameter pulley and an endless belt wound around both pulleys. The passive rotating body 9 may be a gear. In the above embodiments, the engaging portion 7 in which the pair of plate pieces 48 are arranged close to each other along the rotation direction of the sprocket wheel 34 has been described. Only one may be provided, and three or more plate pieces may be provided. In each of the above-described embodiments, the existing pipe replacement device B that cuts and removes a part of the existing pipe 1 in the sealed housing 11 and then attaches the replacement pipe section 13 to a portion corresponding to the removed and removed pipe section 12. Although the existing pipe cutting device A used for the above has been described, as the existing pipe cutting device A of the present invention,
The present invention is not limited to one in which a part of the existing pipe 1 is cut and removed in the sealed housing 11.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an existing pipe cutting apparatus of the present invention, and is a front sectional view before cutting an existing pipe.

FIG. 2 is a plan view of a speed reduction mechanism.

FIG. 3 is a cross-sectional plan view of the screw feed mechanism.

FIG. 4 is a side view showing an engagement portion and a passive rotating body.

FIG. 5 is a sectional front view of the existing pipe in the middle of a cutting process;

FIG. 6 is a side view of an existing pipe cutting device.

FIG. 7 is a longitudinal sectional view of an existing pipe exchange device.

FIG. 8 is a sectional view showing a feeder mechanism of the seal flange member.

FIG. 9 is a schematic view showing a work process of replacing an existing pipe by the existing pipe replacing apparatus.

FIG. 10 is a schematic view showing a work process of replacing an existing pipe by the existing pipe replacing apparatus.

FIG. 11 is a schematic diagram showing a work process of replacing an existing pipe by the existing pipe replacing apparatus.

FIG. 12 is a schematic view showing a work process of replacing an existing pipe by the existing pipe replacing apparatus.

FIG. 13 is a schematic diagram showing a work process of replacing an existing pipe by the existing pipe replacing apparatus.

FIG. 14 is a plan view showing another embodiment of the speed reduction mechanism of the existing pipe cutting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Existing pipe 1A Perimeter wall 2 Cutting bite 3 Cutting unit 4 Guide support part 5 Drive part 6 Screw type feed mechanism 7 Engagement part 8 Screw shaft 9 Passive rotating body 10 Reduction mechanism 41 Worm wheel 42 Worm X Tube axis

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-79430 (JP, A) JP-A 4-128119 (JP, U) JP-A 6-45289 (JP, Y2) (58) Survey Field (Int.Cl. ⁷ , DB name) B26D 1/00-5/42

Claims (2)

(57) [Claims] 1. A cutting unit having a cutting tool for cutting a peripheral wall of an existing pipe along a circumferential direction in a sealed housing, and a sprocket wheel of the cutting unit rotatably supported around a pipe axis. A guide support portion and a sprocket wheel of the cutting unit are wound around the guide support portion .
A drive unit for driving and rotating via an endless chain , wherein a sprocket wheel of the cutting unit includes a screw-type feed mechanism for moving the cutting bite in a pipe diameter direction, and a fixing unit beside a rotation path of the cutting unit. A plurality of protruding pieces that are sequentially engaged with an engaging portion provided at a specific position of the specific position, and a passive rotating body that imparts rotation corresponding to a unit feed amount to the screw-type feed mechanism by the engagement. An existing pipe cutting device, wherein a reduction mechanism is interposed in a rotation transmission system from the passive rotating body to a screw shaft of the screw-type feed mechanism, and the passive rotating body is parallel to a rotation axis of a sprocket wheel. An existing pipe cutting device that is configured to be rotatable around a simple axis. 2. The existing pipe cutting device according to claim 1, wherein said speed reduction mechanism comprises a worm interlocked with said passive rotating body and a worm wheel interlocked with a screw shaft of said screw type feed mechanism.