Patent Publication Number: US-2002011139-A1

Title: Cutting apparatus

Description:
[0001] The present invention is directed to cutting apparatus, and in particular to cutting apparatus for cutting hard material such as concrete and bricks.  
       [0002] Specialised cutting equipment has been developed for cutting such materials. In the Applicant&#39;s U.S. Pat. No. 5,456,011, there is disclosed a cutting tool incorporating two cutting members mounted side by side. This cutting tool is applicable for use in cutting hard materials. As the cutting members must be respectively moved for simultaneous oscillatory movements in opposing directions, this requires a relatively elaborate drive system for the cutting members. The power source for driving the cutting members must also be relatively large to take into account the acceleration forces generated by the movement of these cutting members. Furthermore, because a pair of cutting members are required, the width of the cut produced by the cutting tool will be relatively wide.  
       [0003] It would therefore be advantageous to provide a different type of cutting apparatus for cutting hard materials which can be relatively compact in size and which only requires a single cutting member.  
       [0004] With this in mind, the present invention provides a cutting apparatus including a generally circular cutting member, and a support means for supporting the cutting member for orbital movement about a central area, wherein the cutting member is driven in a rolling orbital motion about the central area during operation of the cutting apparatus.  
       [0005] The cutting member therefore moves in a similar fashion to the movement of a “hula hoop” about the central area.  
       [0006] The cutting member, may have a cutting edge, and each point on the cutting edge may be driven along a continuous convex scalloped path. Alternatively, each point on the cutting edge may be driven along a continuous concave scalloped path.  
       [0007] The support means may include a stator section and rotor section engaging the stator section for said rolling orbital motion therearound. The cutting member may be supported on the rotor section.  
       [0008] According to one preferred embodiment of the cutting apparatus according to the present invention, the stator section may be fixed to a body of the cutting apparatus, with the stator section having an outer wall. The rotor section may have an inner wall. The stator section outer wall and the rotor section inner wall may be at least substantially cylindrical, the diameter of the rotor section inner wall being greater than the diameter of the stator section outer wall. At least a portion of the outer wall of the stator section may be located within the confines of the inner wall of the rotor section such that a point contact is maintained between the inner and outer walls during said rolling orbital motion therebetween.  
       [0009] The rotor section may be rotatably supported on an axle. This axle may be rotatably supported on a moveable carriage. The moveable carriage may itself be slidably supported on a rotatably supported slide support. A power source may drive the slide support for rotational movement. The axis of rotation of the slide support may be laterally offset relative to the axis of rotation of the axle and therefore the rotor to thereby provide an offset drive arrangement.  
       [0010] When the slide support is driven, the offset drive arrangement results in orbital movement of the axle supported on the moveable carriage about the axis of rotation of the slide support. Because the rotor section is supported on the axle, centrifugal force may act to urge the outer cylindrical wall of the stator section against the inner cylindrical wall of the rotor section. Resilient means may also be provided to assist in urging together the inner and outer cylindrical walls. The resilient means may for example be in the form of a coil spring located between an end of the moveable carriage and the slide support to urge the inner cylindrical wall of the rotor section against the outer cylindrical wall of the stator section. This arrangement results in movement of the circular cutting member supported on the rotor section in a rolling motion about the stationery stator section.  
       [0011] Each point on the cutting edge of the cutting member may therefore move along the continuous scalloped path, with each of the scalloped portions of the path being convex in shape.  
       [0012] According to an alternative preferred embodiment of the cutting apparatus according to the present Invention, the stator section may be fixed to a body of the cutting apparatus, and the stator section may have an inner wall, with the rotor section having an outer wall. The rotor section outer wall and the stator section inner wall may be at least substantially cylindrical, the diameter of the rotor section outer wall being less than the diameter of the stator section inner wall. The rotor section may be supported on a moving carriage slidably supported on a slide support in a similar manner to the earlier offset drive arrangement. The principal difference is that at least a portion of the outer wall of the rotor section is located within the confines of the inner wall of the stator section. This also allows a point contact to be maintained between the inner and outer walls during said rolling orbital motion therebetween.  
       [0013] This configuration results in a somewhat different cutting path to the first embodiment. In particular, the cutting path of each point on the cutting edge of the cutting member may be defined by a plurality of concave scallops instead of convex scallops in the case of the first embodiment.  
       [0014] According to yet another preferred embodiment of the cutting apparatus according to the present invention, the central axis of the stator section may be driven for movement in an orbital path about a central rotational point and not fixed as in the earlier embodiments. The stator section may therefore move in an eccentric motion about the central rotational point. The rotor section may be located around the stator section. The movement of the rotor section in a rolling orbital motion about the stator section may be effected by the eccentric movement of the stator section such that the rotor section may “swing” about the stator section in the same manner that a hula hoop swings about the body of a user.  
       [0015] The stator section may include a stator housing having peripheral annular groove, and the rotor section may include an annular ring having an inner peripheral portion supported within the annular groove, a point contact being maintained between the base of the annular groove and the inner peripheral portion during said rolling orbital motion therebetween. The stator section may be driven for movement by an offset drive arrangement includes a drive shaft, a cam supported on the drive shaft and having an axis of symmetry laterally offset relative to the axis of rotation of the drive shaft, wherein the stator housing is supported on the cam for movement therewith.  
       [0016] This arrangement eliminates the need for the drive arrangement of the earlier arrangement incorporating the axle for supporting the rotor and the moveable carriage. The rotor may therefore move about the stator in a rolling motion at least entirely as a result of centrifugal force.  
       [0017] The above described embodiments preferably utilise relatively smooth cylindrical walls for the rotor section and stator section. It is however also envisaged that there be a positive drive between the stator and the rotor by for example, providing cooperating gear teeth respectively on the contacting walls.  
       [0018] Furthermore, it is envisaged that the stator and rotor may be held together by an offset weight arrangement.  
       [0019] The motion of the cutting member has a number of advantages:  
       [0020] a) The movement of the cutting member results in lateral oscillatory movement of the cutting edge of the cutting member. This allows a degree of impacting of the cutting member against the material being cut which facilitates the cutting of hard brittle material such as concrete.  
       [0021] b) The use of this cutting apparatus will be much safer because the cutting member will not readily cut any resilient material such as human flesh as the rotational speed of the cutting member can be relatively slow.  
       [0022] c) Because the cutting member moves in one rotational direction, this will allow the cutting member to continually throw out waste material from the cut during operation thereby preventing slogging of the cutting member. This also provides for a relatively simple drive arrangement for the cutting member.  
       [0023] d) The width of a cut made by the cutting apparatus will be less than the width of the cut produced by the Applicant&#39;s earlier cutting tool described in the above noted US patent.  
       [0024] e) When compared with the Applicant&#39;s earlier cutting tool, the cutting apparatus of the present invention can be relatively compact in size and could be held in one hand. This is in part because the cutting member needs to be driven in one direction only, and the power source for the cutting apparatus can be relatively smaller then the Applicant&#39;s earlier cutting tool. Furthermore, only one cutting member is required. 
     
    
    
     [0025] It will be convenient to further describe the invention by reference to the accompanying drawings which illustrate preferred embodiments of the present invention. Other embodiments of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.  
     [0026] In the drawings;  
     [0027]FIG. 1 is a side cross-sectional view of the support means of a first preferred embodiment of the cutting apparatus according to the present invention;  
     [0028]FIG. 2 is an exploded view of the support means, circular cutting member and driving means of the cutting apparatus of FIG. 1;  
     [0029]FIG. 3 is a diagram showing the path of movement of a point on the cutting edge of the cutting member supported on the support means of FIG. 1;  
     [0030]FIG. 4 is a side cross-sectional view of the support means of a second preferred embodiment of the cutting apparatus according to the present invention; and  
     [0031]FIG. 5 is a side cross-sectional view of the support means of a third preferred embodiment of the cutting apparatus according to the present invention. 
    
    
     [0032] Referring initially to FIGS. 1 and 2, there is shown a cutting apparatus including a generally circular cutting member  1  supported on a support means  2 . The support means  2  includes a rotor  3  having an inner cylindrical wall  4 . The cutting member  1  can be fastened to the rotor  3  by fastening means  5  on a flange  6  of the rotor  3 . The support means  2  also includes a stator  7  which is secured to a main body (not shown) of the cutting apparatus. The stator  7  includes an outer cylindrical wall  8  and an inner cavity  9 . An annular rib  10  is provided on the outer cylindrical wall  8  of the stator  7 . The flange  6  of the rotor  3  is adapted to cooperate with a ring member  11  having an annular shoulder portion  12 . The rotor  3  and the ring  11  can be secured together by the fastening means  5  such that the annular shoulder  12  forms a groove  31  in which the annular rib  10  of the stator  7  can be accommodated.  
     [0033] The rotor  3  is rotatably supported by means of an axle  13  supported on a moveable carriage  14 . A bearing  15  is supported on the moveable carriage  14  to provide for rotational movement of the axle  13 . A key  16  is provided between the axle  13  and the rotor  3  to ensure that the rotor  3  moves together with the axle  13 .  
     [0034] The moveable carriage  14  is slidably supported in a rotatably mounted slide support  19 . The moveable carriage  14  has opposing side rails  18  for engaging cooperating slide grooves  17  in the slide support  19 . A coil spring  20  is provided between the moveable carriage  14  and the slide support  19 . The coil spring  20  urges the moveable carriage  14  out of the slide support  19 . This acts to urge the inner cylindrical wall  4  of the rotor  3  against the outer cylindrical wall  8  of the stator  7 .  
     [0035] The drive means for the cutting apparatus includes a drive shaft  21  driven by means of a V-belt pulley drive including a driven pulley  22 , a V-belt  23 , and a drive pulley  24 . The drive pulley  24  is driven by means of a power source  25  such as an electric motor.  
     [0036] The drive shaft  21  drives the slide support  19  for rotational movement. The moveable carriage  14  is moveable in a lateral direction relative to the rotational axis  27  of the drive shaft  21 . A counter balance  28  is secured by fastening means  29  to the slide support  19 . The rotational axis  20  of the axle  13  supporting the rotor  3  is offset relative to the rotational axis  27  of the drive axle  21 . This produces an offset drive arrangement which results in the rotor  3  being urged at least in part by centrifugal force against the stator  7 . The counter balance  28  on the slide support  19  at least substantially counterbalances the centrifugal force due to the orbital movement of the rotor  3  for rolling motion about the stator  7 .  
     [0037]FIG. 3 shows the path of a point on the cutting edge  30  of the cutting member  1 . Because of the rolling orbital motion of the rotor  3  supporting the cutting member  1 , the cutting edge  30  moves along a “scalloped” path  32  as shown schematically in FIG. 3.  
     [0038]FIG. 4 shows an alternative embodiment of the support means  2  cutting apparatus of the present invention. To facilitate understanding of this embodiment. Components of this embodiment corresponding to components of the embodiment of FIGS. 1 and 2 are designated with the same reference numeral.  
     [0039] The cutting apparatus shown in FIG. 4 operates in a similar way to the embodiment of FIGS. 1 and 2. The cutting member  1  is supported on a rotor  3 . The rotor  3  is rotatably supported by an axle  13  on a movable carriage  14  which in turn is slidably supported on a rotatable slide support  19 . The slide support  19  is driven by a driveshaft  21 . The rotational axis  26  of the axle  13  is offset relative to the rotational axis  27  of the drive shaft  21  in the same manner as in the cutting apparatus of FIG. 1.  
     [0040] The principal difference is that the rotor  3  includes an outer cylindrical wall  50 , and the stator  7  has an inner cylindrical wall  51 . The diameter of the rotor outer wall  50  is less than the diameter of the stator inner wall  51 . Therefore, at least a portion of the rotor  3  can be accommodated within the cavity  9  of the stator  7 . When the rotor is driven in Its rolling orbital motion, the rotor outer wall  50  rolls against the stator inner wall  51 . This is opposite to the first embodiment of FIGS. 1 and 2 and results in the cutting edge of the cutting member  1  moving somewhat in a different path to the embodiment. Each point on the cutting edge moves in a path defined by a plurality of convex scallops.  
     [0041]FIG. 5 shows yet another embodiment of the support means  2  of the cutting apparatus according to the present invention. The stator in this embodiment is provided by a stator housing  05  extending around a cam  64  and supported on the cam  64  by means of a bearing  67 . The cam  60  is mounted on a drive shaft  61  having a central axis of rotation  62 . The cam  60  has an at least substantially cylindrical outer support face  64  upon which the bearing  67  is mounted. The axis of symmetry  63  of the cam  60  is laterally offset relative to the drive shaft axis of rotation  62  so that the cam  60  is driven in an eccentric motion. Rotation of the cam  60  therefore results in eccentric motion of the housing  65 .  
     [0042] The stator housing  65  provides an annular groove  60  extending about the perimeter of the housing  65 . The rotor of the support means  2  of the cutting apparatus of FIG. 5 is in the form of an annular ring  69  having an inner peripheral portion  70  accommodated within the annular groove  68  of the housing  65 . FIG. 5 shows the inner peripheral portion  70  of the annular ring  69  tapering to a peripheral inner edge  71 . Tie shape of the annular groove  68  generally corresponds to the shape of the inner portion of the annular ring  69 , the base  73  of the groove  08  also having tapered sides.  
     [0043] The diameter of the annular ring  69  measured from the peripheral inner edge  71  thereof is greater than the innermost diameter of the base  72  of the annular groove  68  such that a clearance  73  is provided between the said innermost peripheral edge  71  and the base  72  of the annular groove  68 . The cutting member  1  is supported on the annular ring  69  and is movable therewith. The axis of symmetry  66  of the annular ring  69  is also offset relative to the drive shaft axis of rotation  62 .  
     [0044] A mass balance plate  80  is secured to the end of the drive shaft  61 . This plate  80  typically includes a balancing weight  81  and/or apertures  82  provided within the balancing plate  80 . This plate  80  rotates with the drive shaft  61  to help to counterbalance the out of balance forces due to the eccentric motion of the cam  60 , housing  65 , annular plate  69  and cutting member  1 . Because the housing  65  rotates in an eccentric motion about the axis of rotation  62  of the drive shaft  61  and because of the clearance  72  provided between the inner periphery at portion  70  of the annular ring and the base  72  of the annular groove  68  of the housing  65 , this results in the annular ring  69  and therefore the cutting member  1  being swung around the housing  65  in a similar fashion to a hula hoop moving around a person&#39;s waist The annular ring  69  is therefore swung around the housing  65  in the rolling orbital motion because of centrifugal force of the annular ring  69  and the cutting member  1 . To facilitate positive movement of the annular ring  69  about the housing  65 , a plurality of teeth  83  can be provided on the annular ring  69  for engaging the outer surface of the housing  65 . This provides for a more positive drive of the annular ring  69 , and therefore the cutting member  1 .  
     [0045] The cutting apparatus according to the present Invention is relatively inexpensive to manufacture with the components of the support means for the cutting member being simply turned on a lathe. No expensive cast components are required in the cutting apparatus.  
     [0046] The cutting apparatus can also be manufactured as a relatively compact unit which can be held with one hand and which may still have the ability to cut hard material such as concrete. The cutting apparatus is however safe to use because the cutting member will not readily cut resilient matter such as human tissue because of the relatively low rotational speed of the cutting member.  
     [0047] It should also be appreciated that alternative arrangements could be used to drive the cutting member in a rolling orbital motion about a central area. For example, the cutting member could also be driven by induction, air or hydraulic as well as other mechanical means.