FR2509655A1 - CUTTING MACHINE WITH CUTTING WHEEL WITH ROUND EDGE - Google Patents

Abstract

AUTOMATIC CUTTING MACHINE FOR SHEET MATERIAL S, WITH CUTTING WHEEL 70 WITH PERIPHERAL EDGE 71 ROUND CUTTING AND SUPPORT SURFACE 35 CONTINUOUS, HARD AND SMOOTH, THE CUTTING SHEET MATERIAL IS LAY OUT ON THIS SUPPORT SURFACE. THE MACHINE INCLUDES MEANS FOR PRESSING THE PERIPHERAL EDGE OF THE WHEEL AGAINST THE SHEET MATERIAL, AND MEANS FOR SIMULTANEOUSLY MOVING THE WHEEL IN RELATION TO THE SUPPORT SURFACE, SO THAT THE MATERIAL IS CUT BY CRUSHING EFFECT BETWEEN THE EDGE WHEEL PERIPHERAL AND SUPPORT SURFACE.

Description

-1 - The invention relates, in general, to a cutting machine

  sheet material; more particularly, it relates to a machine using a rotary cutting wheel to cut a sheet material into single thickness or low number of

  thicknesses, this wheel being guided on the material.

  We know that we can cut a material into

  sheet in single thickness or with a low number of thick-

  using a rotary cutting wheel, or blade, the material being spread on a hard and smooth support surface and the wheel, pressed against the surface, being rotated on this surface The cutting operation is made by partial slicing and partial crushing between the circumference of the wheel and the support surface The patent US 5,776,072 provides

  description of a cutting machine with rotating wheel

and hard support surface.

  To make the prior machines with cutting wheel and hard support surface, it was felt that the peripheral edge of this cutting wheel should be as tapered as possible so that the sheet material was fully cut. A perfectly tapered cutting wheel should logically lead maximum cutting effect of the wheel driven along

  a cutting path on the material, while reducing

  the necessary pressure between wheel and surface of

  support in order to slice the material Some disadvantages

  However, they are inherent in the use of a tapered rotating wheel in combination with a surface

hard support.

  A first drawback linked to the wheel

  cutting itself is that this wheel is very thin to

  near the cutting edge and can therefore be

  damaged due to the pressure exerted between it and the support surface When the cutting edge is pressed against the support surface, the stresses

  internals developed in the wheel favor chipping

  and the crumbling of the cutting edge.

  A second drawback related to the support surface is that the latter can be notched or

scratched by the tapered wheel.

  The damage to which the drawbacks mentioned lead not only shorten the useful life of the cutting wheel and the surface of

  support, but still adversely influence the ope-

  cutting ration If the wheel is chipped or if the

  support surface is notched, the material to be cut

  per, at the cutting path, sinks into the

  wheel crack or notch on the surface

  port when the wheel is rotated along

  of this path, and the material cannot therefore be com-

completely sliced.

  The invention therefore has as its objective a machine whose rotary cutting wheel is such

  that the drawbacks mentioned are avoided.

  The invention therefore relates to a machine for

  cutting a sheet material in single thickness or with a small number of thicknesses, this material being spread over a support surface The machine therefore has a support surface for the sheet material, a rotary cutting wheel in the form of a disc

  thin circular, translational drive means

  tion of the cutting wheel along a deflection path

  cutting, and means for pressing the edge of the cutting wheel against the support surface when this wheel is driven along the cutting path La

  cutting wheel is characterized, and this is where the new

  value introduced by the invention, in that it comprises

  has a rounded peripheral cutting edge which

  rotates on the support surface and is in contact

250965 E

  -3- cutting tact with sheet material spread over

  the surface The cutting operation is therefore done by se-

  paration by crushing between the round edge of the cutting wheel and the support surface, when the wheel is moved on the support surface. The possibility of damage to the cutting wheel or the support surface is greatly reduced when a round-edge wheel is used for two reasons The first is that a round-edge wheel is significantly more robust near its edge

  peripheral than a wheel of the same diameter with an effective edge

  lé, and is therefore less likely than the latter to crumble or to be chipped The second is that a wheel with a round edge is less likely to scratch a support surface than a tapered wheel The use of a wheel with a round edge reducing the risk of chipping of this wheel or nicking of the support surface, the useful life of these components is extended, and the sheet material is perfectly sliced

along the cutting path.

  The rest of the description refers to the

attached sins which represent:

  Figure 1, a perspective view of a ma-

  chopping machine according to the invention, FIG. 2, a side elevation view of

  the cutting tool and the cutting table of the ma-

  Figure 1, with the charging mechanism connected

  strung with the tool, FIG. 3, a front elevation view of the components of FIG. 2, FIG. 4, on a larger scale, a frontal elevation view of the cutting wheel and its support represented in FIG. 2, FIG. 5, a side elevation view of the cutting wheel and its support shown -4- Figure 4, Figure 6, an elevation view of a wheel

  cutting according to another exemplary embodiment

  form of the invention, Figure 7, an elevational view of another

  cutting wheel according to the invention.

  There is shown in Figure 1 a system, according to the invention, of automatic cutting for material in

  sheet The system has the general reference 10, com-

  carries a cutting table 12, a cutting tool 14,

  and means for driving this tool in transla-

  tion with a carriage (X) 16 which moves above the cutting table 12 in the direction X shown in the drawing, a carriage (Y) 18 mounted on the carriage (X) and which moves with respect to the table and to this carriage (X) in direction Y shown on the drawing,

  a control computer 20 being connected to the cha-

  riots and the tool to control the movements of

  this tool during cutting operations The computer-

  tor 20 obtains the information relating to the cutting program from a memory tape-22 and forms the

  cut command signals from this information

  The control signals are transmitted to the chains.

  riots 16 and 18 by a control cable 24; they-

  drag the tool 14 in translational movement to-

  table top 12, in cutting contact with the

  sheet material S From the information

  tituant the program recorded in the memory tape 22, the computer guides the tool along cutting paths which define, for example, the periphery of the pieces of a pattern which are represented in lines

  dotted on the sheet material.

  The cutting table consists of a frame 30 which rests on a number of feet 32, as well as a plate 34 which defines the working surface -5- on which the sheet material is spread S The working surface 35 of tray 34 is enough

  hard so as not to be damaged by the removal tool

  pressure cutting during cutting.

  The carriage (X) 16 is supported above the cutting table 12 by two racks 48 and 50 arranged longitudinally along the edges of this table in the direction X and supported by brackets

  52 projecting vertically upwards from the

  dre 30 Drive motors and pinions (not shown) mounted in the carriage 16 cooperate with the teeth of the racks 48 and 50 to drive this carriage and the tool 14 in reciprocating motion

  in direction X, above the table,

  to the motion control signals transmitted from-

then computer 20.

  The carriage (Y) 18 is supported by the carriage (X) 16 by means of a guide rail 58 and a drive screw 60 which are arranged in the Y direction between the lateral ends of this carriage 16 The screw

  drive 60 is rotated by an au-

  be drive motor (not shown) controlled from the computer 20, and is engaged in a part

  threaded on the carriage 18, so as to move this carriage

  riot in direction Y above the table The combined movements of the carriages 16 and 18 allow the tool to be driven in translation in any desired direction on the working surface of the table 12, in cutting engagement with the material in sheet to

  cut along the circumference of a pattern piece.

  As we can see more clearly figures

  2 and 3, the cutting tool 14 is suspended on the chain

  riot (Y) 18 by means of a support plate 62 which extends in cantilever from a mount

  adjustable 64 fixed on the projecting end of the chain

  -6- riot The adjustable frame 64 is raised and lowered relative to the work surface of the table 12 at

  by means of a motor (not shown) controlled by the computer

  nator, so that the tool 14 can be brought into contact

  tact of cutting with the sheet material S at the start of a cutting operation, and brought out of contact with this material threads at the end of a cutting operation

  cutting The cutting tool 14 includes a cutting wheel

  section 70 whose peripheral cutting edge cuts

  10th sheet material S by crushing effect, when

  that the tool is pushed down in contact with it

  material under the effect of a force transmitted by the plate

  support tine 62 The cutting wheel 70 is supported

  by a tool holder 72, so that it rotates

  brement around an axis parallel to the work surface

  vail of the table 12, when it is driven on this work surface by the carriages 16 and 18 while it is in cutting contact with the

sheet material.

  The wheel 70 and the support 72 are driven in translational movement with the plate 62, in part by means of a swiveling support shaft 80 which allows the tool to be driven in the movement of

  angular rotation about the axis (Q) 82 perpendicular to

  space on the work surface of the table 12 A rotary drive motor 84 is connected to the shaft 80

  by means of a toothed belt 86 which passes over the pouch

  link 88 of the motor and a large shaft pulley 89 fixed to the upper end of the shaft 80 The rotation commands are formed from the memory tape 22

  by computer 20 and are supplied to the engine

  drag 84 to fix the angular position of the

  cutting wheel so that it always moves

  days tangentially to the edge of the pattern piece,

at each point of this edge.

250965 _

  A charge control mechanism is inter-

  placed between the cutting tool 14 and the carriage

  tool 18 to provide the crushing force which, by moving the tool along the axis (e) 82, brings this tool into cutting contact with the sheet material S spread on the working surface. charge control bears the general reference 100;

  it includes a pneumatic charging cylinder device

  tick or hydraulic 102 which is fixed on a trigger guard 104

  itself fixed on the support plate 62 The device

  load cylinder tif 102 has a rod

  tone 106 which extends coaxially in a central bore of the shaft 80 and is connected, by a thrust bearing 110, to the tool support 72, which is fixed in rotation on the grooves of the lower end of the shaft 80 by a collar 112; so the tool and

  its support rotate with the shaft and slide axially-

  ment along this shaft relative to the support plate 62 The thrust bearing 110 allows the support 72 to drive the cutting wheel 70 in rotation about the axis (0) 82 when the crushing force is

  transmitted by the piston to the cutting wheel.

  The load applied to the cutting wheel, and therefore the crushing force with which the cutting wheel is pushed back into the sheet material S, is determined by the pressure applied to the load control cylinder device 102, by l pressure lines 114 and 116 The applied load must be strong enough for the sheet material to be cut by crushing effect when the wheel moves on its surface After the cutting operation, the pressure in the lines 114 and 116 is brought to a value

  zero, tool 14 is lifted from above the removal table

  cut by the plate 62 and the adjustable frame 64 -8- when the lifting ring 120, fixed at the end

  lower part of the shaft 80, comes into contact with the collar

link 112.

  The diameter of the cutting wheel 72 is within a range limited by practical considerations relating to this type of cutting system. First

  consideration, the wheel diameter must be sufficient

  large so that the upper level of the material to

  cut is not above the mid plane ho-

  rice or axis of rotation of this wheel when its

  periphery is pressed on the support surface, in enga-

  cutting material with sheet material When the upper level of the material is below the aforementioned median plane, this material, along the cutting path, is pressed against the support surface by the cutting edge of the wheel, and no of its parts does

  makes contact with, or obstructs, the tool holder 72.

  Regarding the smallest value of the wheel diameter, it must be considered that this wheel must rotate along a cutting path due to the frictional forces developed between the edge of

  wheel and the sheet material and / or the support surface

  port In order for the wheel to turn, the forces of

  friction must be large enough to oppose

  apply to the frictional forces developed between the

  wheel 70 and the support 72 near the wheel axle.

  In general, the larger the wheel diameter,

  the more the friction drive forces oppose

  easily feels the forces opposing the rotation of

wheel.

  The largest value of the wheel diameter is limited so as to avoid excessive movement of the sheet material when this wheel rotates to

  follow the shape of a curve or angle in the path

  cutting jet The wider the wheel, the more the material

  -9- there is a risk of it being displaced or wrinkling when the

wheel turns around the axis (O).

  Because of the above practical considerations, limiting the range in which the wheel diameter is located, it is recommended to choose as the maximum value of this diameter 76.2 mm, and as the value

minimum 6.35 mm.

  There is shown in more detail, Figures 4 and 5, the cutting wheel, this wheel consisting of a

  thin disc, the thickness of which is practically uniform

  shape between the axial faces of the wheel, and whose cutting edge 71 is rounded The radius of curvature R of the rounded cutting edge 71 may have, for example, a value which is not much smaller than half the length wheel thickness The value of the radius of curvature can, for example, be within a range

between 0.025 and 0.254 mm.

  Several reasons lead to prefer a rounded cutting edge 71 rather than a conventional tapered edge. The crushing force transmitted to the cutting wheel 70 by the load control mechanism leads to the formation of high stresses between the cutting edge and the flat support surface 35 of the plate 34 Strong stresses formed when the

  cutting edge is tapered have ne-

  pomp which adversely affects the cutting operation. One consequence of these high stresses is the deterioration of the cutting edge of the wheel. When the wheel is made of a hard material which is brittle,

  fractures form along the cutting edge which

  fried in fragments separating from the remaining parts of the wheel The resulting small slits and the lack of continuity of the cutting edge result in

  intermittent cutting along the cutting path.

2509655;

-10-

  When a cutting operation is thus poorly performed

  killed, there remain uncut parts of the cutting path between the pattern piece and the material which

  surrounds it, and the material may be damaged by tearing

  cracks at the uncut parts when it is

  pulled to remove the pattern piece.

  In addition, the strong constraints formed

  deteriorate the support surface 35 of the removal table

  cutting when the cutting edge of the cutting wheel is tapered As a rule, the hardness of the support surface is less than that of the cutting wheel It is recommended to choose, for the support surface,

  a hardness not greater than 40 on the scale-

  the Rockwell hardness "C" In principle, this surface should be smooth, but the stresses concentrated the

  along a cutting edge result in its notch-

  As a result, after a period of use

  tion, the support surface 35 has a series of stripes which draw the cut pattern pieces

  -in previous operations These scratches and in-

  sizes have discontinuities and have practical-

  the same effect as discontinuities of the curved edge

  cutting wheel pant The material to be cut

  sinks into the stripes and is not cut locally-

  lie at the intersections of these stripes and the cutting paths. The cutting wheel according to the invention, with its rounded cutting edge 71, practically eliminates the problems of crumbling and notching With its rounded cutting edge, the wheel has a much higher resistance at this edge, and the constraints

  formed, both in this wheel and in the upper surface

  port are reduced accordingly The wheel being more

  resistant and the stresses being reduced, the pos-

  crumbling tendencies are in fact eliminated.

  250 965 e -11 - Likewise, a larger contact surface

  between the cutting edge and the support surface

  reduced by lower stresses in the plateau

  34, which reduces to a level that does not affect the operation-

  cutting the permanent deformation of the surface

  , otherwise eliminate this permanent deformation.

  It has been found experimentally that the cutting edge of the cutting wheel according to the invention, despite its rounded shape, makes it possible to cut

  soft materials, such as woven or non-woven fabrics

  sés The cutting operation is no longer by cutting and crushing effect, but first by effect

  of crushing During tests, it was observed that there remained

  te small traces of pulverized cutting material

  along the cutting line, but we still get

  minus a separation of this material For some ma-

  it may be necessary to increase the crushing force, but this increase, at the level of the contact surface between the rounded cutting edge and the

  support surface, does not result in more strength-

  your constraints and a notching of this surface.

  Figures 6 and 7 show other examples

  ples of realization of the cutting wheel in accordance with

  the invention, these wheels 90 and 92 having cut edges

  pants, 91 and 93 respectively, defined by super-

  flat and narrow cylindrical faces For the reasons mentioned above with regard to the embodiment of FIGS. 3 and 4, the diameter of the wheels 90 and 92 is not more than 76.2 mm and is not less than 6.35 mm Flat cylindrical cutting edges operate

  substantially in the same way as the sharp cutting edge

  rondi 71 having the shape of a curve between the axial end faces of the cutting wheel The flat cutting edges are, in fact, round edges whose radius of curvature tends towards infinity To obtain the same efficiency of cutting with a flat edge, we maintain the width of this edge in a range

between 0.050 and 0.127 mm.

  The wheel 90 shown in Figure 6 is in one piece and differs in this aspect from the wheel 92 shown in Figure 7 The wheel 92 is made of a disc

  thin whose thickness is not greater than the lar-

  flat cutting edge gor 93, with two reinforcement pieces

  forcing 94 and 96 mounted coaxially on each side of the disc to increase the resistance of the wheel to

near axis 98.

  It is understood that the foregoing description

  was made by way of nonlimiting example and that

  variants can be envisaged without, for this, going out

  taken from the scope of the invention For example, the cutting wheels with a rounded cutting edge may be thick

  uniform between their center and their edge, or even this-

  The thickness can increase uniformly, in stages, or according to a hyperbolic law. Bearings can be provided in the center of the wheels, or these wheels can be fixed on the axis which, consequently, pivots in the tool holder. It is important that the bearing structure allows the wheel to rotate freely

  in the tool holder has little play, or prefer-

  rence has no backlash, since the alignment of the wheel in the device is critical for precisely following a cutting path. The precise contour of the rounded cutting edge can be defined between a round shape and a flat shape, with curvatures whose radius increases between the top of the edge and the axial faces

of the wheel.

-13-

Claims (8)

CLAIMS -   1 machine for cutting sheet material, with support having a support surface (35) on   which the sheet material (S) is spread out,   risée in that it comprises: a cutting tool (14) with cutting wheel   (70,90,92) whose peripheral cutting edge is rounded   di (71,91,93), the wheel rotating on the surface of the   port in cutting contact with the sheet material, a translation control mechanism (16, 18) coupled to the cutting tool and the support for controlling the movement of the cutting wheel on the support surface along a predetermined route   for cutting the material spread on this support surface   port, and a load control mechanism (100) for pressing the rounded edge of the cutting wheel against the support surface, so that the operation   cutting is done by crushing the material to be cut   per, between the rounded edge of the wheel and the surface of   support, when this wheel is moved on this over- support face.   2 Machine according to claim 1, charac-   terized in that: the cutting wheel is a thin disc whose thickness is substantially uniform between its axial lateral faces, and the peripheral cutting edge of the wheel   has, between these axial faces, a radius of   bure whose value is only slightly less than   half the thickness of this wheel.   3 Machine according to claim 2, charac-   terized in that: the thickness of the cutting wheel is small compared to its diameter, -14- a range and the diameter of this wheel is located in between 6.35 and 76.2 mm.   4 Machine according to claim 1, charac-   characterized in that the radius of curvature of the rounded edge of the cutting wheel is within a range between 0.001 and 0.254 mm.   Machine according to claim 1, characterized in that the radius of curvature of the rounded edge   of the cutting wheel tends to infinity.   6 Machine according to claim 1, charac-   that the edge of the cutting wheel is flat.   7 Machine according to claim 6, charac-   terized in that the flat edge of the cutting wheel   has a width which is in a range between- be 0.050 and 0.127 mm.   8 Machine according to claim 6, charac-   terized in that the width of the flat edge of the cutting wheel is chosen so that the sheet material is cut without the support surface being scratched under the pressure transmitted by the control mechanism dump.   9 Machine according to claim 1, charac-   terized in that the hardness of the support surface   is less than that of the cutting wheel.