GB2455367A - Rotary pipe cutter, with ratchet and rollers - Google Patents

Abstract

The rotary cutter includes a C-shaped housing 10 having a recess (11, figure 10) containing a rotary cutting unit 20 and an annular one-way ratchet 131. The ratchet engages stops 30, so that the cutting unit can only rotate in one direction in relation to the housing. The cutting unit includes rollers 23, and a blade 22 on an automatic feeding mechanism (24, figure 12). A handle (40, figure 15) can be added. The tool can be used to cut round tubes.

Description

I

ROTARY CUriiR

Field of the Invention

The present invention relates to a rotary cutter, and more specifically to a rotary cutter that includes a C-shaped housing and at least two one-way limiting assemblies.

DeScrlDtiOn of the Prior Art

The traditional pipe cutting devices can be described as follows.

[1] As illustrated in FIG 1, it is a traditional mini-cutter 70 that comprises a main body 71, a movable body 72, and a blade feeding portion 73. The main body 71 is disposed with a guiding slot 711 and two rollers 712. The movable body 72 can slide along the guiding slots 711 of the main body 71. Plus, a cutting blade 721 is mounted on the movable body 72. In operation, the user can insert a pipe 90 and then adjust the blade feeding portion 73 to have a suitable cutting depth. After which, the user should rotate this mini-cutter 70 around this pipe 90 several times. By repeated feeding and rotating actions, the cutting blade 721 will cut this pipe 90 eventually.

It has some major disadvantages such as the holding is not comfortable, it is lack of automatic feeding function, its rotation must over 360 degrees, and the applying force by the user is large.

[2] As shown in FIG 2, it is a traditional automatic-feeding pipe cutter 80. It includes a base 81, an energy storing portion 82, and two rollers 83. This energy storing portion 82 is a resilient and cantilever-like structure. One end of the energy storing portion 82 is secured on the base 81 and the other end of it is disposed with a cutting blade 821. In operation, the user should insert a pipe 90 in. Meanwhile, this inserting action would make the energy storing portion 82 deform and make the cutting blade 821 back a little. At this moment, the cutting blade 821 has a pushing force to feed the cutting blade 821 in. When this traditional automatic-feeding pipe cutter 80 rotates around the pipe 90, the cutting blade 821 will gradually cut into the pipe 90. Finally, this pipe 90 will be cut off.

Concerning this kind of traditional automatic-feeding pipe cutter 80, it still has the disadvantages such as the holding is not comfortable, it is only suitable for certain range of pipe size (it is useless, if diameter of the pipe 90 is too big or too small), its rotation must over 360 degrees, and the applying force by the user is large.

[3] Referring to FIG 3, it is a traditional rotary cutter 60. It comprises a main body 61, a handle 62, a feed knob 63, a rotary unit 64 and a cutter assembly 65. This cutter assembly 65 is disposed on the rotary unit 64. The rotary unit 64 can be rotated inside the main body 61. When the rotary unit 64 moves to a specific position, the user can rotate the feed knob 63 to achieve the manual feeding or withdrawal function for the cutting work. However, the crucial problem is that there is no automatic feeding function.

[4] As shown in FIGS. 4 and 5, the traditional pipe cutter 95 has a handle. It contains a rotary portion 95A and a pair of outer housings 95B. The rotary portion 95A has a cutting blade 951, two rollers 952, and a feeding knob 953. About the outer housings 95B, they are formed by pair of plates 954 facing each other (that can be combined together). The rotary portion 95A only can be rotated toward one direction.

However, because the rotary portion 95A and the feeding knob 953 protrude out, the protruded portions are easy to hit some obstructions nearby.

Moreover, the pipe cutting work is possible to be done in one of the following places or conditions.

[a] The user cuts a pipe under the kitchen sink as shown in FIGS. 6 and 7. A general kitchen sink connects with a cold water suppiy pipe 97 and a hot water supply pipe 98. Plus, there is a drain hose 99 nearby. If the user chooses the traditional mini-cutter 70 or the traditional automatic-feeding pipe cutter 80 to conduct such pipe cutting work, this user must lay down or hunker and then outstretches one hand to reach the pipe to be cut (referring to FIG 6). Many problems still occur, such as the holding is not comfortable, it is lack of automatic feeding function (for the mini-cutter 70), its rotation must over 360 degrees (for the mini-cutter 70 and the traditional automatic-feeding pipe cutter 80), and the applying force by the user is large. Long-time outstretching posture causes the user's body (including back and aim) tired and uncomfortable. Besides, if the user selects traditional rotary cutter 60 or the traditional pipe cutter 95 to proceed the pipe cutting work, it is hard to put in and it will hit the wall 96 or other existing pipe, as illustrated in FIG 7. Consequently, it cannot work. Furthermore, if the user wants to cut the pipe 971 or pipe 981 (as shown in FIG 6) located by the wall 96 and beneath the kitchen sink, it is almost impossible (or highly difficult).

[b] As illustrated in FIG 8, it shows the condition that user wants to cut one of the pipes beneath a boiler (not shown). Under the circumstances, there are four pipes 93A, 93B, 93C, 93D and a U-shaped obstruction 93E (such as a wall). It is hard to cut the pipe 93C. If the user utilizes the traditional mini-cutter 70, the blade feeding portion 73 will hit the neighboring pipes 93B, 93D, or the U-shaped obstruction 93E. If the user selects the traditional rotary cutter 60, it is difficult to install it on the pipe to be cut. Since the opening direction the traditional rotary cutter 60 and the handle 62 of the traditional rotary cutter 60 are perpendicular, the handle 62 will be blocked by other pipes 93A, 93D. Even though the user chooses the traditional automatic-feeding pipe cutter 80, there still are some problems such as it is hard to hold and the user's arm length is not enough.

Of course, if the user selects the traditional pipe cutter 95, the protruded feeding knob 953 and the rotary portion 95A are very easy to hit the neighboring obstructions.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a rotary cutter, which is able to be operated in a narrow space with many obstructions around.

The secondary object of the present invention is to provide a rotary cutter. In which, it is suitable for one-hand operation.

The next object of the present invention is to provide a rotary cutter, which is flexible to change the rotary cutting units with different sizes.

Another object of the present invention is to provide a rotary cutter, which is possible to add an extending handle to apply force easily within a narrow working space.

BREIF DESCRIFION OF THE DRAWINGS

FIG I is a view showing a traditional mini-cutter without automatic feeding function.

FIG 2 is a view illustrating another traditional automatic-feeding pipe cutter.

FIG 3 is a perspective view of a traditional rotary cutter.

FIG 4 is a view of a traditional pipe cutter with a handle.

FIG 5 is a side view of the one shown in FIG 4.

FIG 6 is a view showing a typical working place for a traditional pipe cutting device.

FIG 7 is a cross-sectional view showing the problem of the traditional pipe cutting device will occur.

FIG 8 is a view showing another typical working place for the traditional mini-cutter.

FIG 9 is a perspective view of the present invention.

FIG 10 is a perspective view of the present invention when viewed from another angle.

FIG ii is an exploded view of the present invention.

FIG 12 is an exploded view of the rotary cutting unit of the present invention.

FIG 13 is a plane view depicting the inner parts of the rotary cutting unit of the present invention.

FIG 14 is a view illustrating a user operates this invention.

FIG 15 is a view of the second preferred embodiment of the present invention.

FIG 16 is a view showing the operation process one of the second preferred embodiment of the present invention.

FIG 17 is a view showing the operation process two of the second preferred embodiment of the present invention.

FIG 18 is a view showing the operation process three of the second preferred embodiment of the present invention.

FIG 19 is a view showing a portion of the third preferred embodiment of the present invention.

FIG 20 is a view showing a portion of the fourth preferred embodiment of the present invention.

FIG 21 is a view showing a portion of the fifth preferred embodiment of the present invention.

DETMLED DESCRIPTION OF THE INVENTION

Referring to FIGS. 9, 10, 11, 12 and 13, the present invention is a rotary cutter. It mainly includes a C-shaped housing 10 and at least two one-way limiting assemblies 30.

With regard to the C-shaped housing 10, it has a storing space 11, an outer edge 12, a pair of relatively inner surfaces 13 and an opening width W. The storing space 11 is provided for storing a rotary cutting unit 20 that has a pair of relatively outer surfaces 21, a cutting blade 22, at least two rollers 23, an automatic blade feeding mechanism 24 and at least two limiting assembly recesses 25. One of the relatively inner surfaces 13 is disposed with a substantially annular one-way ratchet portion 131. This C-shaped housing 10 and the rotary cutting unit 20 are coaxial about an axis X. The one-way ratchet portion 131 has a plurality of tilted surfaces l3lA and a plurality of vertical stopping surfaces 13 lB. The automatic blade feed mechanism 24 is able to force the cutting blade 22 feeding automatically.

Concerning these two one-way limiting assemblies 30, they are separated by a distance larger than the opening width W and disposed in the limiting assembly recesses respectively. Each one-way limiting assembly 30 has a sloped guiding surface 31, a holding surface 32, a sliding block 33 and a pushing portion 34. The sloped surface 31 is corresponding to one of the tilted surfaces 131 A of the one-way ratchet portion 131. The holding surface 32 is provided for blocking with one of the stopping surfaces 131B of the one-way ratchet portion 131, so that only one rotational direction between the C-shaped housing 10 and the rotary cutting unit 20 is allowed.

More specifically, the C-shaped housing 10 may be consisted by two half-housings bA, lOB and several securing elements IOC for locking the half-housings IOA, lOB together. Of course, it might be modified into a larger part and a smaller part or into multiple parts.

Furthermore, the cutting blade 22 has a blade shaft 221 and a force-transmitting portion 222.

The automatic blade feeding mechanism 24 includes a curved guider 241 and a resilient force generator 242. This curved guider 241 is secured on the C-shaped housing for limiting a moving path of the blade shaft 221. When the cutting blade 22 contacts with a pipe 50 (or called a workpiece, as shown in FIGS. 13 and 14) to be cut. The cuffing blade 22 rotates and moves along the curved guider 241, so as to gradually reduce a working distance S between the center of the pipe 50 and the center of the blade shaft X for automatic blade feeding. The resilient force generator 242 is provided for applying a pressing force on the force-transmitting portion 222 of the cutting blade 22.

With regard to the practical operation of this invention, as illustrated in FIG 14, a user can select a suitable rotary cutting unit 20 having a proper size to match the diameter of the pipe 50 to be cut and then can install into the C-shaped housing 10. Or, just choose a product having the installed rotary cutting unit 20.

The pipe 50 (held by one hand of the user) should be placed into the storing space 11 of the C-shaped housing 10 (held by another hand of the user). The user can rotate the C-shaped housing around the pipe 50 several times for certain angles. It will achieve the automatic blade feeding of the rotary cutting unit 20. Because the automatic blade feeding technique is a prior art, the detailed description about its principle is omitted.

Therefore, the user can easily hold on this C-shaped housing 10 (approximately equal to the size of a palm) and then rotate for a predetennined angles several times or more. Gradually, the pipe 50 will be cut. The operation is very easy and sample. There is no need to switch the holding hand. The above-mentioned structure is the first preferred embodiment of the present invention.

In addition, as shown in FIG 18, it is the second preferred embodiment of the present embodiment. In which, the C-shaped housing 10 further comprises a connecting recess 14 and an extending handle 40. The connecting recess 14 is provided for securing the extending handle 40 on the C-shaped housing 10. By doing so, the moment arm becomes longer. Hence, it is easier to operate this invention to cut a pipe 50, especially for a pipe 50 made by a hard material.

Besides, if there are two obstructions 51 near the pipe 50 to be cut, as illustrated in FIGS. 14 and 15, it will make the allowable rotating angle ei (as shown in FIG 16) very small, such as on only allowing 80°. Under the circumstances, the user can hold the extending handle 40 secured on the C-shaped housing 10 and then rotate a working angleO2 from a first position P1 (as shown in FIG 16) to a second position P2 (as shown in FIG 17). Since one or more the one-way limiting assemblies 30 lock with the one-way ratchet portions 131, the rotary cuffing unit 20 and the C-shaped housing 10 rotate simultaneously. So, it can gradually cut the pipe 50 during this process. After which, the extending handle 40 can be pulled back from the second position P2 to the first position P1. Meanwhile, all the one-way limiting assemblies 30 will slide over the one-way ratchet portions 131.So, only the C-shaped housing 10 will rotate back. The rotary cutting unit 20 does not move. Then, repeat the rotation from the first position P1 to the second position P2 again for the second blade feeding (and cutting). Just repeat the same procedure mentioned above for several times or more. The pipe 50 will be cut into two parts eventually. Even though there are some obstructions 52 nearby, the required working angle 02 of the present invention is quite small. As a result, this invention still can work at a tiny space with some existing obstructions.

In addition, referring to FIG 19, it is the third preferred embodiment of the present invention. In which, the connecting recess 14 is a square socket having four inner walls 141. Each inner wall 131 has a locking recess 142. One end of the extending handle 40 has a square protrusion 41 having four outer walls 411 corresponding to the inner walls 141. One of the outer walls 411 is disposed with a resilient locking protruding portion 412 for locking into one of the locking recess 412. Based on this design, the extending handle 40 can be secured temporarily.

Of course, this extending handle 40 could be a L-shaped structure (as illustrated in FIG 20; the fourth preferred embodiment) or a two-segment structure that is defined as a structure has two segments connected by a pivoted node (as shown in FIG 21; the fifth preferred embodiment). In the fourth preferred embodiment, the extending handle 40 and the C-shaped housing 10 are separated. After the present invention is installed on the pipe 50 properly, the user can insert the extending handle 40 into the connecting recess 14 as a combined structure (like an integral one) for later operation. Therefore, even though there are three existing pipes 93A, 93B, 93C and a U-shaped obstruction 94E (such as a wall) around, this invention still can work without doubt. That is, this invention can be moved through the space among these pipes 93A, 93B, 93C, and then be installed on the pipe 50. After which, the extending handle 40 can be connected with the C-shaped housing 10. By doing so, this invention can work in an environment full with many obstructions around that the prior art is impossible to work there.

Besides, if the pipe 971 (or 981) as shown in FIG 6 is located in a deep hole or a recessed position that the user is hard to reach, the fifth preferred embodiment of the present invention is an ideal solution. As depicted in FIG 21, the extending handle 40 is a two-segment structure having a first rod 40A, a second rod 40B, and a pivoting portion 40C. Under such circumstances, this invention can be installed on the pipe 971 (or 981) first. Then, this extending handle 40 is connected. After which, the user still can rotate this invention about the axis of the pipe 971 back and forth within a small angle. By repeating these actions, this invention can achieve the cutting work for the pipe located in a hard-to-reach zone that the prior art cannot achieve. That is, based on the special two-segment design, the reachable working position is expanded significantly. This invention almost will not be blocked by any existing obstructions (such as pipes, wall and the like).

Therefore, the advantages and functions of the present invention can be summarized as follows: [I] It can be operated in a narrow space with many obstructions around. If there is a small space having a sufficient working angle, this invention can be operated by repeating partial rotations (less than 360 degrees) to achieve the function of automatic feeding. It is very suitable to work in a position having many existing pipes and obstructions around. In addition, if this invention is combined with an L-shaped or two-segment extending handle, it will be more powerful than ever.

[2] It is suitable for one-hand operation. This invention is highly in compliance with the human-factors engineering. The C-shaped housing is easy to be held by a hand. If there is no any obstruction, this invention can be rotated about 360 degrees. If there are many obstructions, this invention still can be partially rotated within a narrow working angle or space back and forth repeatedly. Concerning the pipe cutting work, the operation is quite easy and smooth. Hence, the overall working efficiency can be significantly increased.

[3] It is flexible to change the rotary cutting units with different sizes. The C-shaped housing has a fixed size. But, it can receive a rotary cutting unit having a specific size for certain pipes. For example, there are three rotary cutting units having the same outer diametet They have different blade cutting working diameters, namely 12 mm to 18mm, 18 mm to 24 mm, and 24 mm to 30 mm (briefly referred as Small Sized Unit, Medium Sized Unit, and Large Sized Unit). Therefore, any one of the rotary cutting units can be installed into the C-shaped housing. Thus, the user can choose a suitable one to install in, so that it is flexible to change the rotary cutting units with different sizes.

[4] It is possible to add an extending handle to apply force easily within a narrow working space. Once the extending handle is secured on the C-shaped housing as an integral one, the moment arm becomes longer. Thus, it will save more applying force during operation.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from scope of the invention as defined by the appended claims. I

ROTARY CUriiR

Field of the Invention

The present invention relates to a rotary cutter, and more specifically to a rotary cutter that includes a C-shaped housing and at least two one-way limiting assemblies.

DeScrlDtiOn of the Prior Art

The traditional pipe cutting devices can be described as follows.

[1] As illustrated in FIG 1, it is a traditional mini-cutter 70 that comprises a main body 71, a movable body 72, and a blade feeding portion 73. The main body 71 is disposed with a guiding slot 711 and two rollers 712. The movable body 72 can slide along the guiding slots 711 of the main body 71. Plus, a cutting blade 721 is mounted on the movable body 72. In operation, the user can insert a pipe 90 and then adjust the blade feeding portion 73 to have a suitable cutting depth. After which, the user should rotate this mini-cutter 70 around this pipe 90 several times. By repeated feeding and rotating actions, the cutting blade 721 will cut this pipe 90 eventually.

It has some major disadvantages such as the holding is not comfortable, it is lack of automatic feeding function, its rotation must over 360 degrees, and the applying force by the user is large.

[2] As shown in FIG 2, it is a traditional automatic-feeding pipe cutter 80. It includes a base 81, an energy storing portion 82, and two rollers 83. This energy storing portion 82 is a resilient and cantilever-like structure. One end of the energy storing portion 82 is secured on the base 81 and the other end of it is disposed with a cutting blade 821. In operation, the user should insert a pipe 90 in. Meanwhile, this inserting action would make the energy storing portion 82 deform and make the cutting blade 821 back a little. At this moment, the cutting blade 821 has a pushing force to feed the cutting blade 821 in. When this traditional automatic-feeding pipe cutter 80 rotates around the pipe 90, the cutting blade 821 will gradually cut into the pipe 90. Finally, this pipe 90 will be cut off.

Concerning this kind of traditional automatic-feeding pipe cutter 80, it still has the disadvantages such as the holding is not comfortable, it is only suitable for certain range of pipe size (it is useless, if diameter of the pipe 90 is too big or too small), its rotation must over 360 degrees, and the applying force by the user is large.

[3] Referring to FIG 3, it is a traditional rotary cutter 60. It comprises a main body 61, a handle 62, a feed knob 63, a rotary unit 64 and a cutter assembly 65. This cutter assembly 65 is disposed on the rotary unit 64. The rotary unit 64 can be rotated inside the main body 61. When the rotary unit 64 moves to a specific position, the user can rotate the feed knob 63 to achieve the manual feeding or withdrawal function for the cutting work. However, the crucial problem is that there is no automatic feeding function.

[4] As shown in FIGS. 4 and 5, the traditional pipe cutter 95 has a handle. It contains a rotary portion 95A and a pair of outer housings 95B. The rotary portion 95A has a cutting blade 951, two rollers 952, and a feeding knob 953. About the outer housings 95B, they are formed by pair of plates 954 facing each other (that can be combined together). The rotary portion 95A only can be rotated toward one direction.

However, because the rotary portion 95A and the feeding knob 953 protrude out, the protruded portions are easy to hit some obstructions nearby.

Moreover, the pipe cutting work is possible to be done in one of the following places or conditions.

[a] The user cuts a pipe under the kitchen sink as shown in FIGS. 6 and 7. A general kitchen sink connects with a cold water suppiy pipe 97 and a hot water supply pipe 98. Plus, there is a drain hose 99 nearby. If the user chooses the traditional mini-cutter 70 or the traditional automatic-feeding pipe cutter 80 to conduct such pipe cutting work, this user must lay down or hunker and then outstretches one hand to reach the pipe to be cut (referring to FIG 6). Many problems still occur, such as the holding is not comfortable, it is lack of automatic feeding function (for the mini-cutter 70), its rotation must over 360 degrees (for the mini-cutter 70 and the traditional automatic-feeding pipe cutter 80), and the applying force by the user is large. Long-time outstretching posture causes the user's body (including back and aim) tired and uncomfortable. Besides, if the user selects traditional rotary cutter 60 or the traditional pipe cutter 95 to proceed the pipe cutting work, it is hard to put in and it will hit the wall 96 or other existing pipe, as illustrated in FIG 7. Consequently, it cannot work. Furthermore, if the user wants to cut the pipe 971 or pipe 981 (as shown in FIG 6) located by the wall 96 and beneath the kitchen sink, it is almost impossible (or highly difficult).

[b] As illustrated in FIG 8, it shows the condition that user wants to cut one of the pipes beneath a boiler (not shown). Under the circumstances, there are four pipes 93A, 93B, 93C, 93D and a U-shaped obstruction 93E (such as a wall). It is hard to cut the pipe 93C. If the user utilizes the traditional mini-cutter 70, the blade feeding portion 73 will hit the neighboring pipes 93B, 93D, or the U-shaped obstruction 93E. If the user selects the traditional rotary cutter 60, it is difficult to install it on the pipe to be cut. Since the opening direction the traditional rotary cutter 60 and the handle 62 of the traditional rotary cutter 60 are perpendicular, the handle 62 will be blocked by other pipes 93A, 93D. Even though the user chooses the traditional automatic-feeding pipe cutter 80, there still are some problems such as it is hard to hold and the user's arm length is not enough.

Of course, if the user selects the traditional pipe cutter 95, the protruded feeding knob 953 and the rotary portion 95A are very easy to hit the neighboring obstructions.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a rotary cutter, which is able to be operated in a narrow space with many obstructions around.

The secondary object of the present invention is to provide a rotary cutter. In which, it is suitable for one-hand operation.

The next object of the present invention is to provide a rotary cutter, which is flexible to change the rotary cutting units with different sizes.

Another object of the present invention is to provide a rotary cutter, which is possible to add an extending handle to apply force easily within a narrow working space.

BREIF DESCRIFION OF THE DRAWINGS

FIG I is a view showing a traditional mini-cutter without automatic feeding function.

FIG 2 is a view illustrating another traditional automatic-feeding pipe cutter.

FIG 3 is a perspective view of a traditional rotary cutter.

FIG 4 is a view of a traditional pipe cutter with a handle.

FIG 5 is a side view of the one shown in FIG 4.

FIG 6 is a view showing a typical working place for a traditional pipe cutting device.

FIG 7 is a cross-sectional view showing the problem of the traditional pipe cutting device will occur.

FIG 8 is a view showing another typical working place for the traditional mini-cutter.

FIG 9 is a perspective view of the present invention.

FIG 10 is a perspective view of the present invention when viewed from another angle.

FIG ii is an exploded view of the present invention.

FIG 12 is an exploded view of the rotary cutting unit of the present invention.

FIG 13 is a plane view depicting the inner parts of the rotary cutting unit of the present invention.

FIG 14 is a view illustrating a user operates this invention.

FIG 15 is a view of the second preferred embodiment of the present invention.

FIG 16 is a view showing the operation process one of the second preferred embodiment of the present invention.

FIG 17 is a view showing the operation process two of the second preferred embodiment of the present invention.

FIG 18 is a view showing the operation process three of the second preferred embodiment of the present invention.

FIG 19 is a view showing a portion of the third preferred embodiment of the present invention.

FIG 20 is a view showing a portion of the fourth preferred embodiment of the present invention.

FIG 21 is a view showing a portion of the fifth preferred embodiment of the present invention.

DETMLED DESCRIPTION OF THE INVENTION

Referring to FIGS. 9, 10, 11, 12 and 13, the present invention is a rotary cutter. It mainly includes a C-shaped housing 10 and at least two one-way limiting assemblies 30.

With regard to the C-shaped housing 10, it has a storing space 11, an outer edge 12, a pair of relatively inner surfaces 13 and an opening width W. The storing space 11 is provided for storing a rotary cutting unit 20 that has a pair of relatively outer surfaces 21, a cutting blade 22, at least two rollers 23, an automatic blade feeding mechanism 24 and at least two limiting assembly recesses 25. One of the relatively inner surfaces 13 is disposed with a substantially annular one-way ratchet portion 131. This C-shaped housing 10 and the rotary cutting unit 20 are coaxial about an axis X. The one-way ratchet portion 131 has a plurality of tilted surfaces l3lA and a plurality of vertical stopping surfaces 13 lB. The automatic blade feed mechanism 24 is able to force the cutting blade 22 feeding automatically.

Concerning these two one-way limiting assemblies 30, they are separated by a distance larger than the opening width W and disposed in the limiting assembly recesses respectively. Each one-way limiting assembly 30 has a sloped guiding surface 31, a holding surface 32, a sliding block 33 and a pushing portion 34. The sloped surface 31 is corresponding to one of the tilted surfaces 131 A of the one-way ratchet portion 131. The holding surface 32 is provided for blocking with one of the stopping surfaces 131B of the one-way ratchet portion 131, so that only one rotational direction between the C-shaped housing 10 and the rotary cutting unit 20 is allowed.

More specifically, the C-shaped housing 10 may be consisted by two half-housings bA, lOB and several securing elements IOC for locking the half-housings IOA, lOB together. Of course, it might be modified into a larger part and a smaller part or into multiple parts.

Furthermore, the cutting blade 22 has a blade shaft 221 and a force-transmitting portion 222.

The automatic blade feeding mechanism 24 includes a curved guider 241 and a resilient force generator 242. This curved guider 241 is secured on the C-shaped housing for limiting a moving path of the blade shaft 221. When the cutting blade 22 contacts with a pipe 50 (or called a workpiece, as shown in FIGS. 13 and 14) to be cut. The cuffing blade 22 rotates and moves along the curved guider 241, so as to gradually reduce a working distance S between the center of the pipe 50 and the center of the blade shaft X for automatic blade feeding. The resilient force generator 242 is provided for applying a pressing force on the force-transmitting portion 222 of the cutting blade 22.

With regard to the practical operation of this invention, as illustrated in FIG 14, a user can select a suitable rotary cutting unit 20 having a proper size to match the diameter of the pipe 50 to be cut and then can install into the C-shaped housing 10. Or, just choose a product having the installed rotary cutting unit 20.

The pipe 50 (held by one hand of the user) should be placed into the storing space 11 of the C-shaped housing 10 (held by another hand of the user). The user can rotate the C-shaped housing around the pipe 50 several times for certain angles. It will achieve the automatic blade feeding of the rotary cutting unit 20. Because the automatic blade feeding technique is a prior art, the detailed description about its principle is omitted.

Therefore, the user can easily hold on this C-shaped housing 10 (approximately equal to the size of a palm) and then rotate for a predetennined angles several times or more. Gradually, the pipe 50 will be cut. The operation is very easy and sample. There is no need to switch the holding hand. The above-mentioned structure is the first preferred embodiment of the present invention.

In addition, as shown in FIG 18, it is the second preferred embodiment of the present embodiment. In which, the C-shaped housing 10 further comprises a connecting recess 14 and an extending handle 40. The connecting recess 14 is provided for securing the extending handle 40 on the C-shaped housing 10. By doing so, the moment arm becomes longer. Hence, it is easier to operate this invention to cut a pipe 50, especially for a pipe 50 made by a hard material.

Besides, if there are two obstructions 51 near the pipe 50 to be cut, as illustrated in FIGS. 14 and 15, it will make the allowable rotating angle ei (as shown in FIG 16) very small, such as on only allowing 80°. Under the circumstances, the user can hold the extending handle 40 secured on the C-shaped housing 10 and then rotate a working angleO2 from a first position P1 (as shown in FIG 16) to a second position P2 (as shown in FIG 17). Since one or more the one-way limiting assemblies 30 lock with the one-way ratchet portions 131, the rotary cuffing unit 20 and the C-shaped housing 10 rotate simultaneously. So, it can gradually cut the pipe 50 during this process. After which, the extending handle 40 can be pulled back from the second position P2 to the first position P1. Meanwhile, all the one-way limiting assemblies 30 will slide over the one-way ratchet portions 131.So, only the C-shaped housing 10 will rotate back. The rotary cutting unit 20 does not move. Then, repeat the rotation from the first position P1 to the second position P2 again for the second blade feeding (and cutting). Just repeat the same procedure mentioned above for several times or more. The pipe 50 will be cut into two parts eventually. Even though there are some obstructions 52 nearby, the required working angle 02 of the present invention is quite small. As a result, this invention still can work at a tiny space with some existing obstructions.

In addition, referring to FIG 19, it is the third preferred embodiment of the present invention. In which, the connecting recess 14 is a square socket having four inner walls 141. Each inner wall 131 has a locking recess 142. One end of the extending handle 40 has a square protrusion 41 having four outer walls 411 corresponding to the inner walls 141. One of the outer walls 411 is disposed with a resilient locking protruding portion 412 for locking into one of the locking recess 412. Based on this design, the extending handle 40 can be secured temporarily.

Of course, this extending handle 40 could be a L-shaped structure (as illustrated in FIG 20; the fourth preferred embodiment) or a two-segment structure that is defined as a structure has two segments connected by a pivoted node (as shown in FIG 21; the fifth preferred embodiment). In the fourth preferred embodiment, the extending handle 40 and the C-shaped housing 10 are separated. After the present invention is installed on the pipe 50 properly, the user can insert the extending handle 40 into the connecting recess 14 as a combined structure (like an integral one) for later operation. Therefore, even though there are three existing pipes 93A, 93B, 93C and a U-shaped obstruction 94E (such as a wall) around, this invention still can work without doubt. That is, this invention can be moved through the space among these pipes 93A, 93B, 93C, and then be installed on the pipe 50. After which, the extending handle 40 can be connected with the C-shaped housing 10. By doing so, this invention can work in an environment full with many obstructions around that the prior art is impossible to work there.

Besides, if the pipe 971 (or 981) as shown in FIG 6 is located in a deep hole or a recessed position that the user is hard to reach, the fifth preferred embodiment of the present invention is an ideal solution. As depicted in FIG 21, the extending handle 40 is a two-segment structure having a first rod 40A, a second rod 40B, and a pivoting portion 40C. Under such circumstances, this invention can be installed on the pipe 971 (or 981) first. Then, this extending handle 40 is connected. After which, the user still can rotate this invention about the axis of the pipe 971 back and forth within a small angle. By repeating these actions, this invention can achieve the cutting work for the pipe located in a hard-to-reach zone that the prior art cannot achieve. That is, based on the special two-segment design, the reachable working position is expanded significantly. This invention almost will not be blocked by any existing obstructions (such as pipes, wall and the like).

Therefore, the advantages and functions of the present invention can be summarized as follows: [I] It can be operated in a narrow space with many obstructions around. If there is a small space having a sufficient working angle, this invention can be operated by repeating partial rotations (less than 360 degrees) to achieve the function of automatic feeding. It is very suitable to work in a position having many existing pipes and obstructions around. In addition, if this invention is combined with an L-shaped or two-segment extending handle, it will be more powerful than ever.

[2] It is suitable for one-hand operation. This invention is highly in compliance with the human-factors engineering. The C-shaped housing is easy to be held by a hand. If there is no any obstruction, this invention can be rotated about 360 degrees. If there are many obstructions, this invention still can be partially rotated within a narrow working angle or space back and forth repeatedly. Concerning the pipe cutting work, the operation is quite easy and smooth. Hence, the overall working efficiency can be significantly increased.

[3] It is flexible to change the rotary cutting units with different sizes. The C-shaped housing has a fixed size. But, it can receive a rotary cutting unit having a specific size for certain pipes. For example, there are three rotary cutting units having the same outer diametet They have different blade cutting working diameters, namely 12 mm to 18mm, 18 mm to 24 mm, and 24 mm to 30 mm (briefly referred as Small Sized Unit, Medium Sized Unit, and Large Sized Unit). Therefore, any one of the rotary cutting units can be installed into the C-shaped housing. Thus, the user can choose a suitable one to install in, so that it is flexible to change the rotary cutting units with different sizes.

[4] It is possible to add an extending handle to apply force easily within a narrow working space. Once the extending handle is secured on the C-shaped housing as an integral one, the moment arm becomes longer. Thus, it will save more applying force during operation.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from scope of the invention as defined by the appended claims.

Claims (5)

1. Arotary cutter comprising: a C-shaped housing having a storing space, an outer edge, a pair of relatively inner surfaces and an opening width; said storing space being provided for storing a rotary cutting unit having a pair of relatively outer surfaces, a cutting blade, at least two rollers, an automatic blade feeding mechanism, and at least two limiting assembly recesses; one of said relatively inner surfaces being disposed with a substantially annular one-way ratchet portion; said C-shaped housing and said rotary cutting unit being coaxial about an axis; said one-way ratchet portion having a plurality of tilted surfaces and a plurality of vertical stopping surfaces; said automatic blade feed mechanism being able to force said cutting blade feeding automatically; at least two one-way limiting assemblies separated by a distance larger than said opening width and disposed in said limiting assembly recesses respectively; each one-way limiting assembly having a sloped guiding surface, a holding surface, a sliding blocks and a pushing portion; said sloped surface being corresponding to one of said tilted surfaces of said one-way ratchet portion, said holding surface being provided for contacting against one of said stopping surfaces of said one-way ratchet portion, so that only one rotational direction between said C-shaped housing and said rotary cutting unit being allowed.

2. Arotaiy cutter as claimed in Claim 1, wherein said C-shaped housing including two half-housings and several securing elements for locking said half-housings together, said cutting blade having a blade shaft and a force-transmitting portion; said automatic blade feeding mechanism including a curved guider and a resilient force generator; said curved guider being secured on said C-shaped housing for limiting a moving path of said blade shaft, when said cutting blade contacting with a pipe to be cut, said cutting blade rotating and moving along said curved guider, so as to gradually reduce a working distance between the center of said pipe and the center of said blade shaft for automatic blade feeding; said resilient force generator being provided for applying a pressing force on said force-transmitting portion of said cutting blade.

3. A rotary cutter as claimed in Claim 1, wherein said C-shaped housing further comprising a connecting recess and an extending handle, said connecting recess being provided for securing said extending handle on said C-shaped housing.

4. A rotary cutter as claimed in Claim 3, wherein said connecting recess being a square socket having four inner walls, each inner wall having a locking recess; one end of said extending handle having a square protrusion having four outer walls corresponding to said inner walls, one of said outer walls being disposed with a resilient locking protruding portion for locking into one of said locking recess.

5. A rotary cutter substantially as hereinbefore described with reference to and as shown in Figures. 9 to 21 of the accompanying drawings.

5. A rotary cutter substantially as hereinbefore described with reference to and as shown in Figures. 9 to 21 of the accompanying drawings.

1. Arotary cutter comprising: a C-shaped housing having a storing space, an outer edge, a pair of relatively inner surfaces and an opening width; said storing space being provided for storing a rotary cutting unit having a pair of relatively outer surfaces, a cutting blade, at least two rollers, an automatic blade feeding mechanism, and at least two limiting assembly recesses; one of said relatively inner surfaces being disposed with a substantially annular one-way ratchet portion; said C-shaped housing and said rotary cutting unit being coaxial about an axis; said one-way ratchet portion having a plurality of tilted surfaces and a plurality of vertical stopping surfaces; said automatic blade feed mechanism being able to force said cutting blade feeding automatically; at least two one-way limiting assemblies separated by a distance larger than said opening width and disposed in said limiting assembly recesses respectively; each one-way limiting assembly having a sloped guiding surface, a holding surface, a sliding blocks and a pushing portion; said sloped surface being corresponding to one of said tilted surfaces of said one-way ratchet portion, said holding surface being provided for contacting against one of said stopping surfaces of said one-way ratchet portion, so that only one rotational direction between said C-shaped housing and said rotary cutting unit being allowed.

2. Arotaiy cutter as claimed in Claim 1, wherein said C-shaped housing including two half-housings and several securing elements for locking said half-housings together, said cutting blade having a blade shaft and a force-transmitting portion; said automatic blade feeding mechanism including a curved guider and a resilient force generator; said curved guider being secured on said C-shaped housing for limiting a moving path of said blade shaft, when said cutting blade contacting with a pipe to be cut, said cutting blade rotating and moving along said curved guider, so as to gradually reduce a working distance between the center of said pipe and the center of said blade shaft for automatic blade feeding; said resilient force generator being provided for applying a pressing force on said force-transmitting portion of said cutting blade.

3. A rotary cutter as claimed in Claim 1, wherein said C-shaped housing further comprising a connecting recess and an extending handle, said connecting recess being provided for securing said extending handle on said C-shaped housing.

4. A rotary cutter as claimed in Claim 3, wherein said connecting recess being a square socket having four inner walls, each inner wall having a locking recess; one end of said extending handle having a square protrusion having four outer walls corresponding to said inner walls, one of said outer walls being disposed with a resilient locking protruding portion for locking into one of said locking recess.