Cutting machine using a diamond wire

Abstract

Diamond Wire Cutting Machine This cutting machine comprises a spool (10) around which the diamond wire is wound. This spool includes: - two end flanges (82, 100) having respective frustoconical faces adapted, by symmetry with frustoconical faces of two adapters, to center the spool on an axis (30) of revolution, and - a drum (104) extending from one of the end flanges to the other end flange, this drum having: - a cylindrical outer face with a circular cross-section around which the diamond wire is wound, and - a central hole through which a drive shaft (32) passes. The drum (104) and the end flanges (82, 100) form a single block of plastic. Fig. 2

Description

Title of the invention: Cutting machine using a diamond wire

[0001] The invention relates to a cutting machine using a diamond wire and a spool for making this cutting machine.

[0002] Diamond wire cutting machines are used to cut very hard parts such as metal or silicon ingots. In these machines, the diamond wire is unwound from a spool called the "pay-off spool" to a spool called the "take-up spool." The pay-off spool delivers fresh diamond wire used to cut the workpiece. After cutting the workpiece or several workpieces, the used diamond wire is wound onto the take-up spool. Thus, the take-up spool essentially contains used diamond wire.

[0003] During workpiece cutting, the tension exerted on the diamond wire is significant. As a result, the radial pressure exerted on the drums of the feeder and take-up spools by the diamond wire is very high. This pressure is called "radial" because it compresses the drum in the direction of its axis of revolution. Furthermore, the speed at which the diamond wire travels is also very high during workpiece cutting. The feeder and take-up spools therefore rotate very rapidly on their axes of revolution. Because of this, the centering of the feeder and take-up spools on their respective axes of revolution must be very precise to minimize vibration of the diamond wire. Vibration of the diamond wire impairs the cutting process.

[0004] Due to the above constraints, the feeder and receiver spools of cutting machines are usually made of metal. Indeed, such metal spools deform very little in response to the radial pressure exerted by the diamond wire on their drums. Furthermore, the dimensional errors in the dimensions of these metal spools are at least five times smaller than the dimensional errors that would be observed if the spools were made of a less hard material such as plastic or resin. The smaller the dimensional errors in the spool's dimensions, the more precise its centering on its axis of revolution. Thus, the use of metal spools reduces the vibrations of the diamond wire during the cutting of the workpiece.

[0005] However, metal spools also have several disadvantages. For example, they are expensive and heavy. They are therefore often returnable, which forces users of cutting machines to return them to the diamond wire manufacturer.

[0006] To reduce the weight of the metal coils used in cutting machines using diamond wire, patent application CN211491757U proposes to manufacture the drum The reel is made using a molded plastic insert. In the reel described in application CN211491757U, the reel flanges are always made of metal to ensure proper centering. This reel is indeed lighter than an all-metal reel. However, it is complex to manufacture because it requires the assembly of various parts made of different materials, which complicates its production and therefore the design of the cutting machine that incorporates it. Furthermore, due to the presence of metal parts, the reel's weight remains quite high, which complicates its handling and thus the use of the cutting machine.

[0007] The invention aims to remedy at least one of these drawbacks by proposing a cutting machine that is simpler to make and use.

[0008] The invention therefore relates to a cutting machine using a diamond wire, this cutting machine comprising:

[0009] - a drive shaft extending along an axis of revolution,

[0010] - a motor capable of driving the drive shaft in rotation, around its axis of revolution, sometimes in one direction and sometimes in the opposite direction,

[0011] - two adapters, each fixed to the drive shaft, each of these adapters comprising a frustoconical centering face centered on the axis of revolution, these frustoconical faces being oriented towards each other,

[0012] - a spool onto which the diamond wire is suitable for being wound during cutting of a single piece by the cutting machine, this coil being immobilized, in rotation and translation, on the drive shaft by the two adapters, this coil comprising:

[0013] - two end flanges comprising respective frustoconical faces suitable, by cooperation in form with the truncated conical faces of the adapters, to center the coil on the axis of revolution, and

[0014] - a drum that extends from one of the end flanges to the other flange at the end, this drum comprises:

[0015] - an external cylindrical face with a circular cross-section on which the diamond wire is wrapped up, and

[0016] - a central hole through which the drive shaft passes,

[0017] in which the drum and the end flanges form a single block of plastic.

[0018] Embodiments of this machine may include one or more of the following features:

[0019] 1) The reel drum comprises:

[0020] - an external tube extending from one of the end flanges to the other end flange, the outer cylindrical face of this outer tube forming the outer cylindrical face of the drum,

[0021] - an inner tube concentric with the outer tube and housed inside the tube external, the inner cylindrical face of this internal tube delimiting the perimeter of the central hole, and

[0022] - radial fins that extend radially from the inner tube to the tube external and extending continuously from one end flange to the other end flange.

[0023] 2) The radial fins are uniformly distributed around the axis of revolution and the The number of radial fins is between eight and twelve.

[0024] 3) The thicknesses of the inner and outer tubes and the thickness of each radial fin is greater than or equal to 2 mm.

[0025] 4) The drum and the end flanges are entirely and solely formed of a single block of molded plastic.

[0026] 5) The plastic block is made of PPS (polyphenylene sulfide) reinforced with fibers of glass.

[0027] 6) The spool drum is capable of withstanding radial pressure exerted by the wire diamond-coated wire wound on this drum exceeding 50 MPa.

[0028] 7) The difference between the diameter of the shaft and the diameter of the central hole of the coil is above 10 pm.

[0029] 8) The coil is either a transmitting coil which initially contains the diamond wire nine is a receiving spool which contains the diamond wire after it has been used to cut the piece.

[0030] The invention also relates to a spool suitable for use in the above-mentioned cutting machine for winding the diamond wire during the cutting of a workpiece by this cutting machine, this spool being adapted to be immobilized, in rotation and translation, on the drive shaft by the two adapters of the cutting machine and this spool comprising:

[0031] - two end flanges comprising respective frustoconical faces suitable, by cooperation in form with the truncated conical faces of the adapters, to center the coil on the axis of revolution, and

[0032] - a drum that extends from one of the end flanges to the other flange at the end, this drum comprises:

[0033] - an external cylindrical face with a circular cross-section on which the diamond wire is wrapped up, and

[0034] - a central hole through which the drive shaft passes,

[0035] in which the drum and the end flanges form a single block of plastic.

[0036] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which:

[0037] - Fig. 1 is a schematic illustration of the architecture of a machine cutting using a diamond wire,

[0038] - [Fig. 2] is an exploded, perspective view of a shaft and a coil of the machine of the [Fig.1],

[0039] - [Fig. 3] is a perspective view of a coil mounted on a shaft of the machine of the [Fig.1],

[0040] - [Fig.4] is a perspective view of an adapter for the machine of [Fig.1],

[0041] - [Fig.5] is a perspective view of a reel of the machine in [Fig.1],

[0042] - [Fig. 6] is a perspective and longitudinal sectional view of the coil of the [Fig.5]

[0043] - [Fig. 7] is a partial, longitudinal sectional view of the coil mounted on the machine shaft of [Fig.1].

[0044] In this description, the terminology, conventions, and definitions of the terms used in this text are introduced in Chapter I. Next, a detailed example of an embodiment is described in Chapter II with reference to the figures. In Chapter III, variations of this embodiment are presented. Finally, the advantages of the different embodiments are specified in Chapter IV.

[0045] Chapter I: Definitions, terminology and conventions:

[0046] In the figures, the same references are used to designate the same elements.

[0047] In the remainder of this description, the well-known characteristics and functions of a person skilled in the art are not described in detail.

[0048] The figures are oriented with respect to an orthogonal XYZ coordinate system, where the X and Y directions are horizontal and the Z direction is vertical.

[0049] The symbol “*” denotes scalar multiplication.

[0050] The expression "an element made of a material A" or the expression "an element made of material A" means that material A represents 90% or 95% of the mass of that element.

[0051] A “hard material” is a material whose hardness on the Mohs scale is greater than 5 or 5.5.

[0052] The terms "exterior" and "external" refer to the parts of a part that are furthest from the axis of revolution of that part.

[0053] The terms "interior" and "internal" refer to the parts of a part that are closest to the axis of revolution of that part.

[0054] Chapter II: Example of an embodiment

[0055] Figure 1 shows a cutting machine 2 using a diamond wire 4. By way of illustration, this machine 2 cuts a hard ingot 6 into several slices. For this purpose, the machine 2 includes, in particular:

[0056] - a transmitting coil 10 on which the new diamond wire is initially wound,

[0057] - a receiving coil 12 onto which the used diamond wire is wound during the use of machine 2,

[0058] - a group 14 of several pulleys around which the diamond wire is wound for create a tablecloth of 16 segments of diamond wire,

[0059] - sensors 18, 20 for the tension of the diamond wire,

[0060] - a motorized platform 22 on an upper face of which the ingot 6 is fixed without any degree of freedom, and

[0061] - an electronic control unit 24 for the various motors of machine 2.

[0062] During the operation of the machine 2, the coil 10 rotates on itself around of a rotational axis 30. In [Fig. 1], the axis 10 is shown as vertical to simplify the diagram of machine 2. However, preferably, the axis 30 is horizontal. To this end, the coil 10 is fixed, without any degrees of freedom in rotation and translation, on a shaft 32 ([Fig. 2]) driven in rotation by an electric motor 34.

[0063] Similarly, the coil 12 rotates about itself around an axis 40 of revolution. In [Fig. 1], the axis 40 is shown as vertical to simplify the diagram of the machine 2. However, preferably, the axis 40 is horizontal. The coil 12 is fixed, without any degrees of freedom in rotation or translation, on a shaft driven in rotation by an electric motor 44.

[0064] The wire 4 unwound from the spool 10 is wound several times around the pulley group 14 to form the sheet 16 of diamond wire segments. For example, here, the group 14 comprises three pulleys 50 to 52, each rotating about its respective axis of revolution. Here, pulleys 50 to 52 rotate, respectively, about axes 54, 55, and 56. These axes 54 to 56 are parallel to the Y direction. Here, axes 54 to 56 are each located at a respective vertex of an equilateral triangle whose base is horizontal.

[0065] In this embodiment, each pulley 50 to 52 is driven in rotation about its respective axis of revolution by a controllable electric motor. For simplicity in [Fig. 1], only the electric motor 58 which drives pulley 50 in rotation has been shown.

[0066] The layer 16 is formed by the segments of the wire 4 which extend parallel to each other between the axes 55 and 56. Here, the segments of the layer 16 each extend parallel to the X direction. The segments of the layer 16 are spaced from each other, in the Y direction, at regular intervals. For example, the layer 16 has more of five or ten segments of wire 4 in order to simultaneously cut several slices in the ingot 6.

[0067] Sensor 18 measures the tension of wire 4 between coil 10 and group 14. Sensor 20 measures the tension of wire 4 between group 14 and coil 12.

[0068] The motorized platform 22 moves the ingot 6 in the Z direction to bring it into contact with the sheet 16 and pushes it against the sheet 16 to cut it into parallel slices. Here, the motorized platform 22 is also capable of moving the ingot 6 in the X direction to produce, for example, curved slices rather than simply parallelepiped-shaped ones.

[0069] Unit 24 controls the various motors of machine 2 to automatically cut the ingot 6 into several slices. In particular, unit 24 controls the drive motors of pulleys 50 to 51 to move the wire 4 back and forth while unwinding new portions of the wire 4 from reel 10 and, simultaneously, winding used portions of the wire 4 onto reel 12. To this end, typically, unit 24 controls motors 34, 44, and the motors of pulleys 50 to 52 by alternating unwinding and winding phases. During each unwinding phase, motors 34, 44, and the motors of pulleys 50 to 52 are controlled to unwind a length PI of the wire 4 from reel 10 and wind this same length PI onto reel 12.During each winding phase, the motors 34, 44 and the pulley motors 50 to 52 are controlled to wind a length P2 of wire 4 onto the reel 10 and unwind this same length P2 from the reel 12. The length P2 is less than the length PI so that the succession of unwinding and winding phases gradually leads to the wire 4 being almost completely unwound from the reel 10 and almost completely wound onto the reel 12. For example, the length P2 is between 0.95*P1 and 0.999*P1 or between 0.98*P1 and 0.995*P1.

[0070] Furthermore, generally, the motor 34 is controlled according to the tension of the wire 4 measured by the sensor 18 in order to regulate the tension of the wire 4, during the unwinding and winding phases, according to a first tension setpoint. Similarly, generally, the motor 44 is controlled according to the tension of the wire 4 measured by the sensor 20 in order to regulate the tension of the wire 4, during the unwinding and winding phases, according to a second tension setpoint.

[0071] For this purpose, typically, the unit 24 includes a microprocessor 60 and a memory 62 containing the instructions and data necessary for the control of the various motors of the machine 2 when these instructions are executed by the microprocessor 60.

[0072] The coil 10 and the mounting of this coil 10 on the shaft 32 will now be described with reference to Figures 2 to 7. Everything described thereafter in the case the particular of the coil 10 and the shaft 32 applies identically to the coil 12 and the drive shaft on which it is mounted.

[0073] Two adapters 70, 72 ([Fig.2]) are used to fix, without any degree of freedom in rotation and translation, the coil 10 on the shaft 32.

[0074] The adapter 70 is removable. For this purpose, the machine 2 includes a mechanism for securing the adapter 70 to the shaft 32. This securing mechanism can be moved, alternately and reversibly, between a locked position and an unlocked position. In the locked position, the adapter 70 immobilizes the reel 10 on the shaft 32, preventing it from moving in translation and rotation. In the unlocked position, the adapter 70 allows the reel 10 to be removed from the shaft 32. For example, in this embodiment, the securing mechanism for the adapter 70 includes a tapped hole 76 (Figures 6 and 7) in a free end 74 ([Fig. 2]) of the shaft 32 and a screw whose head presses the adapter 70 against this free end 74 in the locked position. To simplify the figures, the screw has not been shown. Adapter 70 has a through hole 80 ([Fig.4]) for the passage of the threaded rod of the screw.This hole 80 extends, for example, along axis 30, in the mounted position.

[0075] The free end 74 of the shaft 32 is the one located on the opposite side to a proximal end 78 ([Fig.2]) of this shaft 32. The proximal end 78 is the one that is mechanically connected to the motor 34 to drive the shaft 32 in rotation.

[0076] In the mounted position, the adapter 70 prevents the coil 10 from rotating by means of a form-based cooperation with complementary forms arranged in an end flange 82 (Figures 3, 5, 6) of the coil 10. For example, here, the adapter 70 has two oblong protrusions 83, 84 ([Fig.4]) located on either side of the hole 80. In the mounted position, each of these protrusions 83, 84 is received inside, respectively, oblong recesses 86 and 88 ([Fig.5]) arranged in the flange 82 in order to prevent the coil 10 from rotating on the shaft 32.

[0077] In the mounted position, the adapter 70 also centers the coil 10 on the axis 30 of revolution. For this purpose, the adapter 70 has a frustoconical face 90 ([Fig.4]) which, by combining its shape with a corresponding frustoconical face 92 ([Fig.5]) formed in the flange 82, centers the coil 10 on the axis 30.

[0078] Face 90 is a truncated cone, that is, the portion of a cone situated between two parallel planes. Here, these parallel planes are perpendicular to axis 30 in the mounted position. The leading curve of this cone is a circle centered on axis 30. Its apex is located on the side of the proximal end 78. The apex angle of the cone is greater than 40° or 60° and, generally, less than 160° or 140°. For example, the apex angle is between 80° and 100°. Face 90 here forms a protrusion on an inner face 94 ([Fig. 4]) of a disc 96 ([Fig. 4]) of the adapter 70.

[0079] Face 92 has the same geometric characteristics as face 90 except that it is recessed into the inside of coil 10.

[0080] As illustrated in [Fig.7], in the mounted position, the face 90 comes directly against the face 92 to center the coil 10 on the axis 30.

[0081] The adapter 72 is fixed, without any degree of freedom in translation and rotation, to the shaft 32. To this end, it is fixed to the shaft 32 by any suitable fastening means. For example, it is held in place by a shoulder or press-fitted onto the shaft 32. The adapter 72 is closer to the proximal end 78 of the shaft 32 than the adapter 70. The adapter 72 is positioned on the shaft 32 such that, when the spool 10 is mounted on the shaft 32 and locked in this mounted position by the adapter 70, then an end flange 100 of the spool 10 is directly mechanically supported by the adapter 72.

[0082] Similar to what has been described above in the case of the adapter 70, the adapter 72 immobilizes the coil 10, in translation and in rotation, when the flange 100 is in contact with the adapter 72.

[0083] Here, the flange 100 is the symmetrical counterpart of the flange 82 with respect to a median plane Pm ([Fig.3]) of the coil 10. The median plane Pm is perpendicular to the axis 30 when the coil 10 is mounted on the shaft 32. Under these conditions, the adapter 72 has a frustoconical face and protrusions identical, respectively, to the face 90 and the protrusions 83, 84 of the adapter 70 except that they are turned towards the distal end 74.

[0084] Typically, adapters 70 and 72 are made of metal.

[0085] The coil 10 comprises, in addition to the two flanges 82 and 100, a drum 104 which mechanically connects the two flanges 82 and 100. This drum 104 comprises:

[0086] - an external face 106 (Figures 5 and 6) on which the diamond wire is wound, and

[0087] - a central hole 108 ([Fig.5]) through which the shaft 32 passes in the position ascent.

[0088] The face 106 is a cylinder whose guiding curve is a circle of diameter Di06 and whose generatrix is ​​parallel to the axis 30 in the mounted position. The diameter D106 is typically between 100 mm and 500 mm. The diameter D82 of the flange 82 is larger than the diameter Di06 and is typically between 1.1*Di06 and 1.5*Di06. The length, in the X direction, of the face 106 is between 150 mm and 800 mm.

[0089] The central hole 108 is delimited by an inner face 110 (Figures 5, 6 and 7) of the drum 104. The face 110 is a cylinder whose generatrix is ​​a circle of diameter Duo and whose generatrix is ​​parallel to the axis 30. The diameter Duo is equal to D32+e, where D32 is the diameter of the shaft 32 at the coil 10 and e ([Fig. 7]) is a predetermined clearance. The diameter D32 is typically between 20 mm and 50 mm. The clearance The clearance e is chosen so that, when the radial pressure exerted by the wire 4 on the drum 104 is at its maximum, the face 110 does not bear directly against the shaft 32. Thus, the clearance e facilitates the mounting / dismounting of the spool 10. For this purpose, the clearance e is typically greater than 0.01 mm or 0.1 mm. The clearance e is also generally less than 1 cm.

[0090] The drum 104 is designed to withstand a radial pressure exerted by the diamond wire wound on this drum greater than or equal to 50 MPa and, preferably, greater than or equal to 100 MPa. Generally, the drum 104 is not subjected to a radial pressure greater than 200 MPa, so it is not necessary for it to withstand such a radial pressure.

[0091] In this embodiment, the drum 104 comprises an outer tube 112, an inner tube 114, and radial fins 116. The outer tube 112 ([Fig. 6]) comprises:

[0092] - an outer cylindrical face which corresponds to the outer face 106 of the drum, and

[0093] - an inner cylindrical face 120 ([Fig.6]) turned towards the axis 30.

[0094] The tube 112 also has a reinforcing rib 122 projecting on the inner face 120. The rib 122 is located in the median plane Pm and goes all the way around the axis 30.

[0095] The inner tube 114 ([Fig. 6]) is concentric with the tube 112 and housed inside the tube 112. It has an inner cylindrical face that corresponds to the inner face 110 of the drum and an outer cylindrical face 124 ([Fig. 6]). In this embodiment, the frustoconical face 92 is formed in the end of the tube 114, which further facilitates the insertion of the coil 10 onto the shaft 32.

[0096] The fins 116 ([Fig. 6]) allow a portion of the radial pressure exerted by the wire 4 to be transferred to the inner tube 114 and thus increase the rigidity of the drum 104. To this end, the fins 116 extend radially from the tube 114 to the tube 112. The fins 116 also extend continuously, in the X direction, from the flange 82 to the flange 100. The fins 116 are uniformly distributed around the axis 30. The number Na of fins 116 is preferably even so that each fin 116 is the symmetrical counterpart of another fin 116 with respect to the axis 30. Moreover, advantageously, the number Na of fins 116 is within the range [8; 12]. In this embodiment, the number Na is equal to eight.

[0097] To further increase the robustness of the drum 104 and make the coil 10 usable in the machine 2, the thicknesses of the tubes 112 and 114 and the thickness of the fins 116 are each greater than 2 mm or 4 mm. Generally, the thicknesses of the tubes 112 and 114 and the thickness of the fins 116 are less than 10 mm or 8 mm.

[0098] The coil 10 is entirely and solely formed from a single continuous block of plastic. In this embodiment, the coil 10 is entirely made in a mold comprising several shells into which the molten plastic is injected. After demolding the coil 10, no further machining is performed to adjust its dimensions, particularly those of face 92 and cylindrical face 110. Thus, flanges 82 and 100 and drum 104 form a single, uniform, and continuous block of material. The fact that the coil 10 is formed by molding a plastic is easily detectable by examining the coil, as molding is a manufacturing process that leaves traces in the resulting part. These traces may include the location of the parting line, the location of the air intake vents, the location of the molten plastic inlets, or other features. Preferably, to achieve very high hardness, the plastic used to mold the coil 10 is glass fiber-reinforced polyphenylene sulfide (PPS). Typically, the glass fibers represent at least 20% or 30% of the plastic's volume.For example, the plastic used to mold reel 10 is PPS GF40 which contains 40% glass fibers.

[0099] Chapter III: Variants:

[0100] Coil variants:

[0101] Alternatively, the direction curve of the frustoconical faces 90, 92 is not a circle. This non-circular guide curve is preferably symmetrical with respect to the axis 30 of revolution. In this case, the protrusions 83, 84 can be omitted because the frustoconical faces themselves prevent, by cooperation of form, the rotation of the coil 10 on the shaft 32 in the mounted position.

[0102] The frustoconical face 92 can also be formed, in part or in whole, in the ends of the fins 116 located at the level of the flange 82 or in the end of the external tube 112 located at the level of the flange 82.

[0103] Other embodiments of the drum 104 are possible. For example, alternatively, the tubes 112 and 114 and the radial fins 116 are replaced by a single tube whose thickness is sufficient so that its outer face forms the outer face 106 of the drum and whose inner face delimits the perimeter of the hole 108.

[0104] The drum and flanges can be produced by machining rather than molding. For example, a single block of plastic is machined so that the drum and flanges form a single piece of plastic. In this case, the geometry of the drum and flanges must be adapted to such machining. For example, the embodiment in the preceding paragraph is adapted to manufacturing the reel 10 by machining a block of plastic because the fins 116 are omitted. However, without the fins 116, the drum has fewer perforations and is therefore heavier.

[0105] Alternatively, the reel may include additional parts. For example, the reel includes an end cap that clips onto one of the flanges 82 or 100. This clip-on cap is intended, for example, to serve as a removable support for a label. In this case, the clip-on cap can be removed before mounting the reel on the drive shaft. However, if the clip-on cover does not obstruct the central hole 108 and does not interfere with the centering of the reel by shape cooperation with the adapters, then the clip-on cover can also be left in place even when using the reel in machine 2.

[0106] The coil can also be made of plastics other than glass fiber reinforced PPS. For example, in an alternative, the glass fibers are replaced by other fibers capable of reinforcing the plastic, such as metal fibers. In a simplified alternative, the plastic has no reinforcing fibers. In another alternative, the PPS is replaced by another special plastic that achieves the desired hardness. This other special plastic can be one of the plastics belonging to the group consisting of PPA (polyphthalamide), PA (polyamide), PBT (polybutylene terephthalate), PC (polycarbonate), PEEK (polyetheretherketone), POM (polyoxymethylene), PEI (polyetherimides), PEK (polyetherketone), PAI (polyamide-imide), PPSU (polyphenylsulfone), PSU (polysulfone), and PES (polyethersulfone).

[0107] Other variants:

[0108] Many other embodiments of the cutting machine are possible. For example, the axes of revolution 30 and 40 of the coils 10 and 12 can be vertical.

[0109] One of the coils 10 and 12 can be conventionally made of metal. In this case, for this metal coil, adapters 70 and 72 can be omitted because the diameter Dn0 can then be adjusted very precisely so as to be, for example, between D32 and D32 + 3 µm. Preferably, it is coil 12 that is made of metal in this case.

[0110] Group 14 may include a different number of pulleys. For example, in one variant, group 14 includes only the two pulleys 51 and 52. In another variant, group 14 includes more than three pulleys.

[0111] In another embodiment, the plate 22 is stationary and it is the pulley group 14 that moves in the Z and / or X directions.

[0112] In a simplified embodiment, the motorized platform 22 only allows the ingot 6 to be moved in the Z direction.

[0113] In another simplified embodiment, one of the sensors 18 and 20 is omitted. In another variant, both sensors 18 and 20 are omitted. In this case, the motor driving the rotation of the coil is not controlled according to the tension of the wire 4 wound on this coil.

[0114] Other mechanisms for attaching the adapter 70 to the distal end 74 of the shaft 32 are possible. For example, instead of being screwed onto the distal end 74, the adapter 70 is clipped onto the distal end 74.

[0115] The adapter 72 can also form a single block of material with the shaft 32. Conversely, in another variant, the adapter 72 is also removable.

[0116] Several of the variants described above can be combined in the same embodiment.

[0117] Chapter IV: Advantages of the described embodiments:

[0118] Making the end flanges out of plastic reduces the weight of the reel and thus simplifies the use of the cutting machine. Furthermore, this weight reduction is achieved without compromising the reel's centering on the drive shaft and while still allowing the flanges and drum to be manufactured by molding. Indeed, the dimensional tolerances on molded plastic parts are much larger than on the dimensions of the same parts made of metal. Because of this, it was expected that the reel's centering would be much less accurate when using molded plastic flanges than when using metal flanges. It is assumed that this is also why, in application CN211491757U, the end flanges are made of steel and not plastic.However, it has been observed that the dimensional errors seen in plastic molded parts are primarily caused by plastic shrinkage, which occurs during the cooling of molten plastic. As a result, at a given location, the error in the diameter of the frustoconical face 92 is significantly greater than if the flange were made of metal. However, in the case of the frustoconical face 92, the shrinkage is uniform around its entire circumference. Because of this, the plastic frustoconical face 92 is centered on the axis 30 of revolution just as well as if it were made of metal. Thus, the plastic end flanges 82 and 100 allow for sufficiently precise centering of the coil 10 on the axis 30 of revolution, making it suitable for use in a cutting machine with a diamond wire.

[0119] Furthermore, manufacturing the drum 104 and the end flanges 82, 100 from the same block of plastic substantially simplifies the production of the reel, since the flanges 82, 100 and the drum 104 can be molded together in a single operation. Simplifying the production of the reel 10 also simplifies the design of the cutting machine 2.

[0120] The use of external tubes 112 and internal tubes 114 mechanically connected to each other by radial fins 116 makes it possible to further reduce the weight of the coil 10 while being able to withstand the radial stress exerted by the diamond wire 4 wound on this coil.

[0121] The fact that the number of radial fins 116 is between eight and twelve makes it possible to obtain a drum 104 that resists the radial stresses exerted by the wire diamond 4 when used in the cutting machine 2 while leaving sufficient space between the fins to facilitate unmolding of the coil.

[0122] The fact that the thicknesses of the internal tube 112 and external tube 114 and of the radial fins 116 are greater than or equal to 2 mm makes it possible to achieve the robustness necessary to withstand the radial pressure exerted by the diamond wire 4 when cutting a part.

[0123] Making the reel 10 from a single block of molded plastic simplifies its manufacture compared to a reel such as the reel described in application CN211491757U. Indeed, in application CN211491757U, the reel also includes a metal insert to reinforce its drum.

[0124] The use of glass fiber reinforced PPS, which is an unusual plastic for making coils, makes it possible to obtain a coil that can withstand the radial pressure exerted by the diamond wire 4 when cutting a part while limiting the amount of material used to make it.

Claims

Demands

1. A cutting machine using a diamond wire, this cutting machine comprising: - a drive shaft (32) extending along an axis (30) of revolution, - a motor (34, 44) capable of driving the drive shaft in rotation about its axis of revolution, sometimes in one direction and sometimes in the opposite direction, - two adapters (70, 72) each fixed on the drive shaft, each of these adapters having a frustoconical centering face (90) centered on the axis of revolution, these frustoconical faces being turned towards each other, - a spool (10, 12) onto which the diamond wire is capable of being wound during the cutting of a workpiece by the cutting machine, this spool being immobilized, in rotation and translation, on the drive shaft by the two adapters, this spool comprising: - two end flanges (82, 100) comprising respective frustoconical faces (92) suitable,by cooperation of form with the frustoconical faces of the adapters, to center the coil on the axis of revolution, and - a drum (104) which extends from one of the end flanges to the other end flange, this drum comprising: - a cylindrical outer face (106) of circular cross-section on which the diamond wire is wound, and - a central hole (108) through which the drive shaft passes, characterized in that the drum (104) and the end flanges (82, 100) form a single block of plastic.

2. Cutting machine according to claim 1, in which the coil drum comprises: - an external tube (112) extending from one of the end flanges to the other end flange, the outer cylindrical face of this external tube forming the outer cylindrical face of the drum, - an inner tube (114) concentric with the outer tube and housed inside the outer tube, the inner cylindrical face (110) of this inner tube delimiting the perimeter of the central hole, and - radial fins (116) which extend radially from the inner tube to the outer tube and which extend continuously from one end flange to the other end flange.

3. Machine according to any one of the preceding claims, wherein the radial fins (116) are uniformly distributed around the axis of revolution and the number of radial fins is between eight and twelve.

4. Machine according to any one of the preceding claims, wherein the thicknesses of the inner (114) and outer (112) tubes and the thickness of each radial fin (116) is greater than or equal to 2 mm.

5. Machine according to any one of the preceding claims, wherein the drum (104) and the end flanges (82, 100) are entirely and solely formed from a single block of molded plastic.

6. Machine according to any one of the preceding claims, wherein the plastic block is made of PPS (polyphenylene sulfide) reinforced with glass fibers.

7. Machine according to any one of the preceding claims, wherein the spool drum is capable of withstanding a radial pressure exerted by the diamond wire wound on this drum greater than 50 MPa.

8. Machine according to any one of the preceding claims, wherein the difference between the diameter of the shaft and the diameter of the center hole of the coil is greater than 10 pm.

9. Machine according to any one of the preceding claims, wherein the spool (10, 12) is either a sending spool which initially contains the new diamond wire or a receiving spool which contains the diamond wire after its use in cutting the workpiece.

10. A spool suitable for use in a cutting machine according to any one of the preceding claims for winding diamond wire during the cutting of a workpiece by that cutting machine, this spool being adapted to be immobilized, in rotation and translation, on the drive shaft by the two adapters of the cutting machine and this reel comprising: - two end flanges (82, 100) having respective frustoconical faces (92) capable, by cooperation of form with the frustoconical faces of the adapters, of centering the coil on the axis of revolution, and - a drum (104) extending from one of the end flanges to the other end flange, this drum comprising: - an external cylindrical face (106) with a circular cross-section around which the diamond wire is wound, and - a central hole (108) through which the drive shaft passes, characterized in that the drum (104) and the end flanges (82, 100) form a single block of plastic.

Images