Device for cutting thermoplastic pipes

Abstract

A device for cutting a tube made of thermoplastic material, comprising: a tool (4) for cutting a tube (T); an arm (3) for supporting the tool (4), the arm (3) being movable between a non-operating configuration (P1) in which the tool (4) is disengaged from the tube (T) and an operating configuration (P2) in which the tool (4) is engaged in the tube (T) to exert a cutting action on the tube (T); a rod (6) which can be constrained to the arm (3); a supporting device (7) configured to move the rod (6); a locking unit (8) for reversibly constraining the arm (3) and the rod (6), and a disengaging device (9) which moves the arm (3) from the operating configuration (P2) to the non-operating configuration (P1).

Description

Technical Field

[0001] The invention relates to a device for cutting pipes made of thermoplastic material.

[0002] In particular, the invention relates to a device for cutting tubes made of thermoplastic material in an automatic cutting machine. Background Art

[0003] In systems for producing tubes made of thermoplastic material, an automatic cutting machine is generally located together with the extrusion station producing the continuous tube, more specifically downstream of the latter.

[0004] Automatic cutting machines usually have a cutting unit or device which is equipped with one or more separate cutting tools.

[0005] Typically, the cutting unit or device is movable in a rotational direction about the pipe.

[0006] According to a preferred embodiment, during the cutting step, the cutting device is moved along the longitudinal axis of the tube in synchronism with the feeding of the tube.

[0007] During the cutting step, the cutting tool is fed radially until it comes into contact with the tube to penetrate the thickness.

[0008] At the same time, the cutting unit rotates around the axis of the pipe so that the cutting tool can perform a complete circumferential cut, thus forming a pipe.

[0009] Once the cut has been completed, the cutting tool will be moved radially away from the pipe so that there is no longer contact between the cutting tool and the pipe profile.

[0010] Subsequently, the cutting device is returned longitudinally in a direction opposite to the feeding direction of the tube to a suitable starting position for making a new cut.

[0011] The tools usually used for cutting pipes are represented by fixed blades, rotating idler blades or circular blades rotated by a suitable drive motor.

[0012] The cutting tool is selected according to the characteristics of the tube to be cut, both in terms of the material constituting the tube and in terms of the thickness to be cut.

[0013] Prior art devices for moving the cutting tool have either pneumatic or hydraulic drives.

[0014] More specifically, hydraulic actuation requires a rather complex and bulky system, typically comprising a control unit with control valves, one or more electric motors, a tank and a hydraulic pump.

[0015] As far as operation is concerned, in the cutting machines currently used there are problems associated with the hydraulic drive of the above-mentioned cutting elements employed, in particular in the event of a malfunction or failure of the electrical power supply.

[0016] In effect, as previously described, the cutting device moves synchronously with the longitudinal direction of the tube during the cutting step, penetrating into the interior of the tube.

[0017] In the event of a power failure or an emergency stop of the automatic cutting machine, the tube is pushed by the action of the extrusion station and continues to be fed longitudinally at least for a predetermined time.

[0018] However, the cutting device no longer has the necessary energy for a suitable movement and can no longer be radially disengaged from the pipe and is ultimately pulled along by the pipe itself.

[0019] Under the dragging effect of the pipe, the cutting tool and the automatic cutting machine are generally in danger of being damaged, which has a negative impact on the possibility of using the new cut.

[0020] The solutions currently devised to overcome this drawback involve the use of elastic elements coupled to hydraulic cylinders which control the radial movement of the cutting device relative to the profile of the pipe.

[0021] These resilient elements (usually compression springs) are compressed by the same hydraulic cylinders as the cutting element is pushed to penetrate the pipe being processed.

[0022] In the event of an electrical failure and therefore a hydraulic failure, the cylinder is no longer able to compress the spring to which it is connected, which is therefore free to release its relatively accumulated elastic energy and thus withdraw the cutting tool from the pipe.

[0023] Alternatively, a similar result can be achieved by inserting a suitable hydraulic accumulator in place of the spring, which is loaded under normal operating conditions with the purpose of introducing accumulated pressurized oil into the circuit when necessary to keep the cutting tool away from the pipe even in the absence of electrical energy.

[0024] The above solution has some drawbacks, in particular regarding its complexity in addition to the already fully articulated main hydraulic system.

[0025] In addition, for certain materials and specific cutting processes, it can easily control the speed, force and trajectory of the tool penetration.

[0026] However, in order to guarantee certain features in the systems currently used, specific proportional hydraulic valves must be inserted and dedicated algorithms for controlling them must be processed.

[0027] Despite the presence of these additional components, it is not possible to achieve a high level of precision due to the usual unavoidable response inertia of hydraulic systems.

[0028] To this one must also add the variability in behavior that hydraulic systems have depending on operating conditions such as temperature.

[0029] Patent document WO 2019 / 244015 A2 describes a device for cutting pipes made of plastic material in an automatic cutting machine, comprising: a tool for cutting pipes made of plastic material; a first rocker arm supporting the cutting tool, capable of moving between a non-operating structure and an operating structure, in which the tool is disengaged from the pipe and in which the tool is designed to exert its cutting action on the pipe; a second arm for controlling the first arm, the second arm being operably connected to the first arm to move the first arm at least between its non-operating and operating structures, the second arm comprising a first electric actuator and a supporting body, the supporting body being slidably connected for changing its reciprocating position between its closed position and its spaced position. Summary of the invention

[0030] The object of the present invention is to overcome the drawbacks of the prior art by means of a device for cutting tubes made of thermoplastic material which is at the same time effective, precise and easy to control.

[0031] Another object of the present invention is to provide a cutting device that can be immediately deactivated in the event of a power failure or emergency, allowing the cutting tool to be disengaged from the pipe being processed to avoid damage to the cutting tool and, generally, to the cutting tool already installed therein.

[0032] Another object of the invention is to provide a cutting device which comprises a limited number of components and which is therefore particularly compact and inexpensive.

[0033] According to the present invention, these and other objects, which will become more apparent from the following description, are achieved by a device for cutting a tube made of thermoplastic material, comprising the technical characteristics described in one or more of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] With reference to the above objects, the technical features of the present invention are clearly described in the following claims, and its advantages will become more apparent from the following detailed description with reference to the accompanying drawings, which show preferred non-limiting embodiments of the present invention by way of example, in which:

[0035] - Figure 1 and Figure 2 is a front view of the cutting device in an embodiment in two operating configurations during a cutting procedure;

[0036] - Figures 3 to 7 is in different structures corresponding to the steps of handling emergency situations Figure 1and Figure 2 A front view of a cutting device;

[0037] - Figure 8 Cutting away of parts for clarity during an operation for cutting a tube made of thermoplastic material Figure 1 and Figure 2 A three-dimensional view of the cutting device. DETAILED DESCRIPTION

[0038] Reference Figure 1 , reference numeral 1 denotes as a whole an apparatus for cutting a tube T made of thermoplastic material.

[0039] The cutting device 1 is generally inserted in an automatic cutting machine (not shown), in a system for forming tubes T made of thermoplastic material (also not shown).

[0040] Typically, the automatic cutting machine is positioned downstream of the continuous extrusion station and is designed to cut sections of the tube starting from the continuous tube T coming from the aforementioned extrusion station.

[0041] The tube T made of thermoplastic material comes out of the extrusion station in a continuous manner and is cut into tubes of predetermined sizes.

[0042] The cutting device 1 is supported by a rotatable structure 2 of the cutting machine.

[0043] Preferably, the rotatable structure 2 has an annular shape with a central hole in which the tube T to be cut is positioned.

[0044] The rotatable structure 2 is configured to rotate in a substantially known manner about a first centre axis of rotation X1 .

[0045] As will be explained in more detail below, other components of the cutting device 1 are connected to the rotatable structure 2 and are rotationally driven by the movement of said structure 2 .

[0046] Preferably, the first axis X1 is perpendicular to Figures 1 to 7 The first axis X1 is substantially consistent with the longitudinal symmetry axis of the tube T coming from the above-mentioned extrusion station.

[0047] Advantageously, during the cutting operation, the cutting device 1 is movable along the aforementioned first axis X1 , both in the feeding direction of the tube T and in the direction opposite to the feeding direction of the tube.

[0048] Preferably, the cutting device 1 moves synchronously with the tube T when it moves in the feeding direction of the tube.

[0049] According to the present invention, the feeding direction of the tube T is from Figures 1 to 7The page comes out, according to the three-dimensional Figure 8 It is from left to right.

[0050] As shown in the drawings, the cutting device 1 comprises an arm 3 .

[0051] As also shown, the arm 3 supports the cutting tool 4 at a first free end 3A.

[0052] In other words, the cutting tool 4 is pivoted at the first free end 3A of the arm 3 .

[0053] In the embodiment shown in the figures, the cutting tool 4 is an idle circular blade.

[0054] In another embodiment not shown, the cutting tool 4 is a fixed blade, also called a cutting edge.

[0055] According to yet another embodiment not shown, the cutting tool 4 is a circular motor-driven blade, suitably equipped with suitable means for driving the blade.

[0056] According to one aspect, the arm 3 is movable about the pin 5 .

[0057] According to an embodiment, the pin 5 is integral with the rotatable structure 2 .

[0058] As shown in the figures, the arm 3 pivots about a pin 5, preferably at a second free end 3B opposite the first free end 3A. .

[0059] According to a further aspect, the arm 3 is movable in a rotational direction about the pin 5 .

[0060] In the embodiment shown, the arm 3 pivots on the pin 5 to rotate about the second axis X2 .

[0061] Preferably, the second axis X2 is parallel to the above-mentioned first axis X1 of rotation of the rotatable structure 2 .

[0062] More specifically, the arm 3 is movable between a non-operating configuration P1 , in which the tool 4 is disengaged from the tubular T, and an operating configuration P2 , in which the tool 4 is engaged in said tubular T to exert its cutting action.

[0063] In other words, in the non-operating configuration P1 , the tool 4 is not in contact with the tubular T, e.g. Figure 1 shown.

[0064] On the other hand, in the operating configuration P2, the tool 4 is brought into contact with the tube T to exert a cutting action, e.g. Figure 2 shown.

[0065] As also shown, the cutting device 1 comprises a rod 6 .

[0066] Preferably, the rod 6 is movable in a rotational direction about the pin 5 .

[0067] As shown in the figures, the lever 6 is pivotable about the pin 5 , preferably at a first free end 6A.

[0068] In the embodiment shown, the lever 6 pivots on the pin 5 to rotate about the second axis X2 .

[0069] More specifically, the rod 6 is movable between a rest configuration P3 and a movable configuration P4 .

[0070] More specifically, the difference between the rest configuration P3 and the active configuration P4 lies in the distance from the first axis X1 of the second free end 6B of the rod 6 opposite the first free end 6A.

[0071] In the static configuration P3, if Figure 1 As shown, the second free end 6B of the rod 6 is larger than that in Figure 2 The active configuration P4 is shown closer to the first axis X1 .

[0072] like Figure 8 As shown, the cutting device 1 comprises a supporting device 7 .

[0073] Said support means 7 extends longitudinally along a longitudinal axis Y and has two respective longitudinally opposite ends 7A, 7B, one being an upper end and the other being a lower end.

[0074] Said supporting means 7 are operatively connected to the rod 6 .

[0075] According to the embodiment shown, the support device 7 is connected at its upper end 7A to the rod 6 , preferably by a pivot.

[0076] Similarly, the rod 6 is connected at its free end 6B to the support means 7, preferably by means of the above-mentioned pivot.

[0077] Preferably, at its lower end 7B, the support means 7 is then pivoted on the above-mentioned rotatable structure 2, preferably by means of respective pins, about an axis parallel to the second axis X2.

[0078] According to one aspect, the support device 7 comprises a support body 72 .

[0079] Preferably, the support body 72 is positioned at the lower end 7B of the support device 7 .

[0080] Also preferably, the support body 72 represents the connection point between the bearing device 7 and the rotatable structure 2 .

[0081] The support body 72 is designed as a further element of the mobile support device 7 .

[0082] According to another aspect, the support device 7 comprises a first electric actuator 71 .

[0083] Advantageously, the use of an electric actuator makes it possible to keep the overall dimensions and weight limited relative to another type of actuator, such as a hydraulic or pneumatic actuator, which would require, for example, a rotatable structure 2 mounted on or close to the hydraulic or pneumatic control unit, respectively.

[0084] Advantageously, the use of an electric actuator ensures a higher precision of action and an easier adjustment of this action, even with regard to speed and force.

[0085] Preferably, the first electric actuator 71 is supported by a supporting body 72 and represents the connection point to the rod 6 .

[0086] In effect, as shown, the first electric actuator 71 extends from the support body 72 to the upper end 7A.

[0087] Preferably, the first electric actuator 71 is a linear electric actuator.

[0088] Still more particularly, the first electric actuator 71 is configured to exert its action in a direction parallel to or coincident with the longitudinal axis Y of the support device 7 .

[0089] As shown, the first electric actuator 71 advantageously includes a body 73 for housing an electromechanical device.

[0090] The first electric actuator 71 comprises a rod 74 emerging from the body 73 and designed to move longitudinally along the aforementioned longitudinal axis Y.

[0091] The rod 74 defines, together with the associated end protruding from the body 73 , the upper end 7A of the above-mentioned support device 7 .

[0092] According to an embodiment, the first electric actuator 71 comprises the use of an electromechanical transmission.

[0093] Preferably, the first electric actuator 71 comprises a lead nut and screw system and an electric motor for moving the rod 74 along the longitudinal axis Y.

[0094] According to one aspect of this invention, the support means 7 , and more particularly the first actuator 74 , are configured to move the rod 6 between said rest configuration P3 and active configuration P4 , preferably via a lever 74 .

[0095] More specifically, due to the action of the first actuator 71, the rod 74 can move between a retracted position and an extended position, wherein the retracted position is Figure 1 and the rod 74 is mainly contained in the body 73 in the retracted position and in the extended position Figure 2 , and the rod 74 is primarily exposed (ie, emerges) from the body 73 in the extended position.

[0096] pass Figure 2 The action of the first actuator 71 indicated by the arrow mark F1 in FIG. 7 allows the rod 74 to be transferred from the retracted position to the extended position.

[0097] pass Figure 5 The action of the first actuator 71 indicated by the arrow mark F7 in FIG. 7 allows the rod 74 to be transferred from the extended position to the retracted position.

[0098] According to another aspect of the present description, the cutting device 1 comprises a locking unit 8 .

[0099] The locking unit 8 is operatively connected to the arm 3 and the rod 6 .

[0100] The locking unit 8 is movable between an engaged configuration P5 and a free configuration P6.

[0101] When the locking unit 8 is in the engaged configuration P5 , the arm 3 and the rod 6 are integral with each other.

[0102] More specifically, if the locking unit 8 is in an engaged configuration, no mutual rotation is allowed between the arm 3 and the rod 6, such as Figure 1 , Figure 2 and Figure 7 , Figure 8 As shown in the embodiment.

[0103] In this configuration, the arm 3 and the rod 6 in their entirety substantially constitute a rocker arm, that is to say substantially a single body that rotates about the pin 5 under the action of the first electric actuator 71 .

[0104] On the other hand, when the locking unit 8 is in the free configuration P6 , the arm 3 and the rod 6 are movable relative to each other.

[0105] More specifically, if the locking unit 8 is in a free configuration, mutual rotation is allowed between the arm 3 and the rod 6, such as Figure 4 , Figure 5 As shown in the embodiment.

[0106] In the embodiment shown, when the locking unit adopts the free configuration P6, the arm 3 can rotate about the pin 5 relative to the rod 6, e.g. Figure 4 Indicated by arrow mark F5.

[0107] Preferably, the locking unit 8 comprises a contact element 81 .

[0108] According to an embodiment, the contact element 81 has a bird's beak or tooth shape.

[0109] The contact element 81 is preferably connected to the rod 6 in a movably manner by means of a pin.

[0110] More specifically, the contact element 81 rotates between the locking position P7 and the releasing position P8.

[0111] More specifically, when the contact element 81 is in the locking position 7 , the contact element 81 engages with said arm 3 and at least partially prevents the arm 3 from rotating freely relative to the aforementioned rod 6 .

[0112] via Figure 1 In the embodiment shown by way of example in FIG. 8 , the contact element 81 comes into contact with the contact seat of the arm 3 at its free end.

[0113] This contact between the contact element 81 and the contact seat of the arm 3 at least partially prevents a free rotation between the arm 3 itself and the rod 6 .

[0114] exist Figures 1 to 7 In the embodiment shown, the contact between the contact element 81 and the contact seat of the arm 3 prevents a rotation of the arm 3 relative to the rod 6 in the counterclockwise direction.

[0115] According to another aspect, when the contact element 81 is in the release position P8 , it is not engaged with said arm 3 and allows, at least partially, a free rotation relative to the aforementioned rod 6 .

[0116] via Figure 3 In the embodiment shown by way of example in FIG. 8 , the contact element 81 does not come into contact with the contact seat of the arm 3 in the release position P8 at the above-mentioned free end.

[0117] The absence of contact between the contact element 81 and the contact seat of the arm 3 allows, at least in part, a free rotation between the arm 3 itself and the rod 6 in one direction.

[0118] like Figure 4 As indicated by arrow reference F5 in FIG. 8 , the gap between contact element 81 and contact seat of arm 3 allows rotation of arm 3 relative to rod 6 in the counterclockwise direction.

[0119] Preferably, the locking unit 8 comprises a second actuator 82 .

[0120] According to an embodiment, the second actuator 82 is an electromechanical actuator.

[0121] Advantageously, the second actuator 82 is operatively connected to the contact element 81 .

[0122] Preferably, the second actuator 82 is connected to the contact element 81 at its end opposite to the contact end of the contact seat of the arm 3 .

[0123] According to one aspect of the invention, the second actuator 82 is configured to move the contact element 81 between the locking position P7 and the releasing position P8.

[0124] In the embodiment shown in the figures, the second actuator 82 is movable between a locking configuration, in which the contact element is held in the locking position P7 , and a releasing configuration, in which the contact element is held in the releasing position P8 .

[0125] exist Figure 1 to Figure 2 and Figures 6 to 8 In the embodiment shown, the second actuator 82 is in the locked configuration, that is to say extended, so as to hold the contact element 81 in the locked position P7 , that is to say in the contact seat of the arm 3 .

[0126] exist Figures 3 to 5 In the embodiment shown, the second actuator 82 is in the release configuration, that is to say retracted, so as to keep the contact element 81 in the release position P8 , that is to say outside the contact seat of the arm 3 .

[0127] The transition from the locked configuration to the released configuration results in a rotation of the contact element 81, which is Figure 3 The contact seat protrudes as shown by the arrow mark F3 in FIG.

[0128] exist Figures 3 to 5 In the illustrated embodiment, the transition from the release configuration to the locking configuration results in a rotation of the contact element 81, which is Figure 6 Enter from the contact seat of arm 3 as indicated by the arrow mark F11 in FIG.

[0129] In an alternative embodiment not shown, the contact element 81 comprises a fixing pin located on the arm 3 or on the rod 6, which, in the locking position P7, intercepts a specific seat which is located on the rod 6 or on the arm 3 depending on the position of the contact element 81, and in the release position P8, the fixing pin protrudes from the specific seat.

[0130] Preferably, the locking unit 8 comprises a second power supply device 82A for supplying energy to the second actuator 82 .

[0131] According to an embodiment, the second power supply device 82A is a battery capable of storing sufficient energy for driving the second actuator 82 .

[0132] More generally, the second power supply 82A may be any device designed to store sufficient energy for driving the second actuator 82; the second power supply 82A may be located anywhere and may be defined by one or more elements.

[0133] Advantageously, the use of the second power supply 82A allows operation of the second actuator 82A even in the absence of main power supply.

[0134] Preferably, the locking unit 8 comprises a reset lever 83 .

[0135] The reset lever 83 is connected to the arm 3 and the rod 6 .

[0136] In the embodiment shown in the figures, the reset lever 83 is provided with a groove 84 .

[0137] Preferably, the groove 84 has an elongated shape, e.g. Figure 1 shown.

[0138] Preferably, the arm 3 comprises a pin 3C coupled to said reset lever 83 , this pin 3C being slidably inserted in the slot 84 .

[0139] In other words, the groove 84 serves as a guide groove for the sliding of the connecting pin 3C, so that the connecting pin 3C is inserted into the groove 84 itself with clearance.

[0140] More specifically, the connecting pin 3C is movable between a first position P9 in which the connecting pin 3C substantially abuts the first end 84A of the slot 84 and a second position P10 in which the connecting pin 3C substantially abuts the second end 84b of the slot 84 .

[0141] In this specification, the term “substantially abutting” is used as there may be no actual contact made between the connecting pin 3C and the first end 84A at the first position P9 or the second end 84B at the second position P10 .

[0142] If no contact is made between the connecting pin 3C and the first end 84A at the first position P9 or the second end 84B at the second position P10, then the first position P9 is the position of the first end 84A of the connecting pin 3C close to the groove 84 and the second position P10 is the position of the second end 84b of the connecting pin 3C close to the groove 84.

[0143] In effect, the presence of the further impedance element prevents movement of the connecting pin 3C prior to contact with either the first end 84A or the second end 84B, as described in more detail below.

[0144] In the embodiment shown in the drawings, the first end 84A of the slot 84 is spaced further from the arm 3 than the second end 84B of the slot.

[0145] More specifically, when the connecting pin 3C is in the first position P9, free rotation between the arm 3 and the rod 6 in one direction is at least partially prevented.

[0146] In the embodiment shown in the drawings, when the connecting pin 3C is in the first position P9, the arm 3 is rotated in the clockwise direction ("clockwise" refers to the rotation direction) relative to the rod 6. Figures 1 to 7 ) is prevented from rotating.

[0147] Therefore, the simultaneous presence of the contact element 81 in the locking position P7 and the connecting pin 3C in the first position P9 (corresponding to the action of the appropriate impedance element described) prevents the arm 3 from rotating freely relative to the rod 6, not only in the clockwise direction but also in the counterclockwise direction.

[0148] In this case, the arm 3 is integral with the rod 6 and both contribute to forming a rocker arm.

[0149] Preferably, the locking unit 8 comprises a third actuator 85 .

[0150] According to an embodiment, the third actuator 85 is an electromechanical actuator.

[0151] According to one aspect of the invention, a third actuator 85 is operatively connected to the reset lever 83 .

[0152] According to one aspect, the third actuator 85 is configured to move the reset lever 83 .

[0153] More specifically, the third actuator 85 is configured to return the arm 3 to the starting relative position with respect to the rod 6 before the free rotation due to the release position of the contact element 81 .

[0154] Effectively, with the occurrence of the release state of the contact element 81 , the connecting pin 3C has been transferred from the first position P9 to the second position P10 .

[0155] The third actuator 85 is also configured to move the reset lever 83 to bring the connecting pin 3C from the contact state of the second end 84B to the contact state of the first end 84A.

[0156] The third actuator 85 acts to Figure 6 and Figure 7 , more particularly by means of arrows marked F9 and F13 in the respective figures.

[0157] The function of the third actuator 85 is described in more detail below.

[0158] Advantageously, the use of an electric actuator in the locking unit 8 allows the overall dimensions and weight to be kept limited.

[0159] Advantageously, the use of an electric actuator in the locking unit 8 ensures a higher precision of the action and an easier adjustment of this action.

[0160] According to another aspect of the invention, the cutting device 1 comprises a disengaging device 9 .

[0161] The release device 9 is configured to move the arm 3 from the operating position P2 to the inoperative position P1 .

[0162] In other words, the disengaging device 9 is configured to move the arm 3 of the carrier tool 4 from a state of engagement with the tube T to a state of disengagement from the tube.

[0163] Preferably, the release device 9 comprises at least one connecting element 91 connected to the rod 6 and to the arm 3 .

[0164] The longitudinal extension of the connecting element 91 defines the direction of the release action produced by the release device 9 .

[0165] In one embodiment, as shown in the drawings, the connecting element 91 includes at least one rod 91A.

[0166] The rod 91A is rotatably connected to the arm 3 at one end of the arm 3 .

[0167] On its opposite side, the rod 91A is connected to the stem 6 via a constraining element 93 , preferably in a rotatable manner.

[0168] Preferably, the constraining element 93 is represented by a bushing.

[0169] Advantageously, the use of a bushing allows relative movement between the rod 6 and the bar 91A, the bar 91A sliding inside the bushing.

[0170] Preferably, the release device 9 comprises at least one energy storage element 92 .

[0171] The energy storage element 92 is preferably operatively connected to the connecting element 91 .

[0172] According to an embodiment, energy storage element 92 is configured to store mechanical energy.

[0173] According to another embodiment, the energy storage element 92 is configured to store electricity.

[0174] According to an embodiment, energy storage element 92 is configured to store magnetic energy.

[0175] More specifically, the energy storage element 92 is configured to retain a large amount of stored energy when the locking unit 8 is in the engaged configuration P5.

[0176] More specifically, the energy storage element 92 is configured to release the amount of stored energy when the locking unit 8 is in the free configuration P5.

[0177] According to the embodiment shown in the figures, the energy storage element 92 is a spring 92A.

[0178] According to one embodiment, the spring 92A is a coil spring.

[0179] The spring 92A is thus configured to store elastic potential energy when the locking unit 8 is in the engaged configuration P5 and to release said elastic potential energy when the locking unit 8 is in the free configuration P6.

[0180] Preferably, the spring 92A is placed on the rod 91A.

[0181] Preferably again, a spring 92A acts between one end of the rod 91A and its constraining element 93 together with the rod 6 .

[0182] In the embodiment shown in the figures, a spring 92A acts between the free lower end of the rod 91A and the bushing, which has a restraining element 93 .

[0183] The spring 92A can also move between a compressed state and an extended state, the compressed state being, for example, Figure 1 As shown, when the locking unit 8 is in the engagement configuration P5, the extended state, for example Figure 4 Shown is when the locking unit 8 is in the free configuration P6.

[0184] In the embodiment shown in the drawings, when the spring 92A is already in the compressed position, the compression resistance of the spring 92A prevents the connecting pin 3C from contacting the first end 84A of the slot 84 when the connecting pin 3C is in the first position P9.

[0185] In other words, when the connecting pin 3C is at the first position P9 , there is a gap between the pin itself and the first end 84A of the slot 84 .

[0186] According to an alternative embodiment, the disengagement means 9 comprise a torsion spring, preferably mounted on the pin 5 , the torsion axis of which preferably coincides with the second axis X2 .

[0187] The operation of the cutting device 1 both in an optimum working state and in a state for handling a fault will be described below with the help of the drawings.

[0188] Without limiting the scope of the invention, reference will be made below in non-limiting examples to an embodiment of the device 1 shown in the accompanying drawings. It should be understood that the replacement of certain components of the device 1 with equivalent elements does not affect the validity of the following.

[0189] In use, such as Figure 1 As shown, the cutting device 1 is in a standby state before a new cutting process of a tube 2 made of thermoplastic material is started from the above-mentioned extrusion station (not shown).

[0190] exist Figure 1In the waiting state shown, the arm 3 of the device 1 is in the inoperative configuration P1 , the lever is in the rest configuration P3 and the locking unit 8 is in the engaged configuration P5 .

[0191] More specifically, the contact element 81 is in the locking position P7 and the connecting pin 3C is in the second position P9 , constraining the arm 3 to the rod 6 .

[0192] As regards the support device 7 , the rod 74 is retracted inside the body 73 , thereby maintaining the rod 6 in the rest configuration P3 .

[0193] Spring 92A is pre-compressed and rests on rod 91A.

[0194] The spring 92A remains in a compressed state while the locking unit 8 is held in the engaged configuration P5.

[0195] In order to cut the pipe T, the first electric actuator 71 is activated to bring it to the extended position, which first electric actuator is activated by Figure 2 The action indicated by the arrow mark F1 in FIG. 7 moves the rod 74 .

[0196] In this way, the rod 6 moves from the rest configuration P3 to the active configuration P4.

[0197] Because the locking unit 8 maintains the engaged configuration P5, the arm 3 moves from the inoperative configuration P1 to the operative configuration P2 in an integrated manner with the lever 6, as shown in FIG. Figure 2 As shown by the arrow marked F2.

[0198] In this position, the tool 4 comes into contact with the tube T to exert its cutting action.

[0199] The fact that during the cutting of the tube T the rotatable structure 2 (and the cutting device 1 integrated therewith) rotates about the first axis X1 will not be taken into account and will therefore not be described in detail.

[0200] However, it must be understood that, during the cutting operation, the structure 2 performs at least one rotation of 360° about the first axis X1 .

[0201] If the cutting process is performed normally, then the tool 4 is Figure 8 The tube T is completely cut as shown.

[0202] The action of the first electric actuator 71, which is equivalent to and opposite to the action indicated by the arrow mark F1, is to return the device 1 to Figure 1 Required for the wait state shown.

[0203] However, if there is a fault, such as, for example, an emergency stop or an interruption in the power supply, the first electric actuator 71 will not be able to move the device 1 to the standby position and thereby disconnect the tool 4 from the pipeline T, unless the device 1 is equipped with an uneconomical and cumbersome system (UPS) for storing energy, which will overcome the absence of active power and directly supply the first actuator 71 to reverse the movement.

[0204] The feeding of the tube T will not stop and it will continue its movement even if only by inertia.

[0205] Due to the engagement with the tool 4, longitudinal movement of the tube T will be transmitted to the device 1 with subsequent damage to the device.

[0206] Therefore, in order to disengage the cutting tool 4, the second actuator 82 is changed from the locking configuration (ie, extended) to the releasing configuration (ie, retracted) and commands the contact element 81 to move from the locking position P7 to the releasing position P8, as shown in FIG. Figure 3 As shown by the arrow mark F3.

[0207] Advantageously, the second actuator 82 exerts its action in a pulse-like manner.

[0208] Following the movement of the contact element 81 , the locking unit 8 is in a free configuration P6 , in which a mutual rotation between the arm 3 and the lever 6 is allowed.

[0209] When the locking device 8 is in the free configuration P6, the spring 92A can release the stored elastic potential energy and change from the compressed configuration to the extended configuration, such as Figure 4 As shown by the arrow mark F4.

[0210] As the spring 92A extends, the rod 91A slides in a bushing representing a restraining element 93 .

[0211] This sliding action acts on the arm 3, which is dragged along by the sliding of the rod 91A, as shown in FIG. Figure 4 Rotate as indicated by the arrow mark F5.

[0212] The range of this movement is limited by the longitudinal extension of the slot 84, although there are additional mechanical impedance elements (described below) so that the connecting pin 3C may not come into contact with the first ends 84A and 84B of the slot 84.

[0213] Effectively, as the arm 3 rotates, the connecting pin 3C transitions from the first position P9 to the second position P10 , thereby moving closer to the second end 84B of the slot 84 .

[0214] Preferably, the rotation of the arm 3 , indicated by the arrow reference F5 , is limited by mechanical contact elements, not shown, between the arm 3 and the rod 6 .

[0215] The rotation as indicated by the arrow mark F5 moves the arm 3 to the non-operating configuration P1 and moves the tool 4 away from the pipe T, completely disengaging the tool 4 from the pipe T, as shown in FIG. Figure 4 As shown by the arrow mark F6.

[0216] In this case, the cutting device 1 is safely placed and does not suffer damage due to the feeding of the tube T.

[0217] As the fault condition is processed, and therefore when power is returned to supply components of the device 1, the device must be returned to Figure 1 The extruder is then forced to a standby state so that it can continue its operation, that is, cut the subsequent section of the tube being extruded.

[0218] The first electric actuator 71 is Figure 5 The action indicated by the arrow marked F7 moves the tube 71 so as to bring it to the retracted position and, therefore, the rod 6 to the rest configuration P3.

[0219] This movement causes the cutting tool 4 to move further away from the tube T, by Figure 5 Indicated by the arrow mark F8 in FIG.

[0220] In this state, the third actuator 85 is then Figure 6 The reset lever 83 is moved as indicated by the arrow mark F9 in FIG.

[0221] In other words, the third actuator 85 moves the rod 83 toward the rod 6 .

[0222] Since the connecting pin 3C is in the second position P10 , the arm 3 is driven by the locking lever 73 and rotated as indicated by the arrow mark F10 while being maintained in the non-operating position P1 .

[0223] The rotation of the arm 3 returns the contact element 81 , still in the release position P8 , to the contact seat of the arm 3 .

[0224] The second actuator 82 is transformed from the release configuration (ie, retracted) and controls the contact element 81 to move from the release position P8 to the locking position P7, as shown in FIG. Figure 6 As shown by the arrow mark F11.

[0225] At the same time, with the action of the third actuator 85, the spring 92A is returned to the compressed configuration and the rod 91A is moved by Figure 6 Slide in the direction indicated by the arrow mark F12.

[0226] The spring 92A returns to store elastic potential energy which will be released again when a new emergency state is reached.

[0227] The third actuator 85 is again as Figure 7 Moving the resetting lever 83 as indicated by the arrow marking F13 moves the connecting pin 3C to the first position P9, thereby allowing, if necessary, a new possibility of rotation relative to the lever 6, now having the pin 3C positioned again inside the slot 84 for the entire sliding length.

[0228] Figure 7 The structure of the cutting tool 1 in the embodiment is basically the same as that of Figure 1 The waiting state shown is consistent and tool 1 is ready to restart with Figure 1 and Figure 2 The state of the cutting operation.

[0229] The cutting device 1 according to the invention achieves the intended objectives and brings important advantages.

[0230] A first advantage associated with the device of the invention is that, in the event of a power failure, maximum safety is guaranteed thanks to the possibility of disconnecting the cutting device from the pipe being processed in a quick and safe manner.

[0231] Another advantage is due to the fact that an electric drive has been used, rather than a hydraulic or pneumatic drive of the cutting tool known from the prior art.

[0232] The use of electric actuators makes the entire device more compact and lightweight, and more versatile and simpler in both installation and maintenance.

[0233] Furthermore, the use of electric actuators results in an optimization of the cutting operation, thanks to the higher inherent precision of electric drives compared to hydraulic or pneumatic drive operations.

[0234] Moreover, thanks to the use of an electric actuator, the cutting action can be adjusted very simply, differentiating between the radial speed of the tool relative to the pipe between the step of radial movement and the step of cutting, or varying and controlling the force and penetration speed of the tool in a continuous manner, for example as required for certain plastic materials, thus avoiding unwanted fragility of the pipe or achieving a poor quality cut.

[0235] Controlling the cutting process in a dynamic and instantaneous manner using conventional motion systems (pneumatic or hydraulic) is not feasible due to excessive structural complexity and low control accuracy.

Claims

1. A device (1) for cutting a tube (T) made of thermoplastic material in an automatic cutting machine, comprising: - a cutting tool (4) for cutting said tube (T) made of thermoplastic material, - an arm (3) carrying the tool (4) and movable in rotation about a pin (5) between a non-operating configuration (P1) in which the cutting tool (4) is disengaged from the tube (T) and an operating configuration (P2) in which the cutting tool (4) is engaged with the tube (T) to exert its cutting action, - a rod (6) movable in rotation about the pin (5) between a stationary configuration (P3) and a movable configuration (P4); - a support device (7) operatively connected to the rod (6) to move the rod (6) between the static configuration (P3) and the active configuration (P4), the support device (7) comprising a first electric actuator (71) and a support body (72) of the first electric actuator (71); The device (1) is characterized in that the device (1) includes a locking unit (8), which is operatively connected to the arm (3) and the rod (6) and is movable between an engaged structure (P5) and a free structure (P6), wherein at the engaged structure (P5), the arm (3) and the rod (6) are integral with each other due to the constraint defined by the locking unit (8), and at the free structure (P6), the arm (3) and the rod (6) are movable relative to each other; and the device (1) includes a disengaging device (9), which is constructed to move the arm (3) from the operative structure (P2) to the non-operative structure (P1) when the locking unit (8) is in the free structure (P6).

2. The device (1) as claimed in the preceding claim, characterized in that The locking unit (8) comprises a contact element (81) which is movably connected to the rod (6) and is movable between a locking position (P7) and a release position (P8), in which the contact element (81) is engaged with the arm (3) to prevent the arm (3) from freely rotating relative to the rod (6) and in which the contact element (81) is not engaged with the arm (3) to allow the arm (3) to freely rotate relative to the rod (6).

3. The device (1) according to claim 2, characterized in that The locking unit (8) comprises a second actuator (82) operatively connected to the contact element (81) and configured to move the contact element (81) between the locking position (P7) and the releasing position (P8).

4. The device (1) according to claim 2, characterized in that The locking unit (8) comprises a reset lever (83) connected to the arm (3) and the rod (6) and provided with a slot (84), and wherein the arm (3) comprises a connecting pin (3C) which is slidably inserted inside the slot (84).

5. The device (1) according to claim 4, characterized in that The locking unit (8) includes a third actuator (85), which is at least configured to move the reset rod (83) and the connecting pin (3C) from a first position (P9) to a second position (P10), wherein the connecting pin (3C) contacts the first end (84A) of the slot (84) in the first position (P9) and contacts the second end (84B) of the slot (84) in the second position (P10).

6. The device (1) according to any one of claims 1 to 5, characterized in that The release device (9) comprises at least one connecting element (91) and at least one energy storage device (92), the at least one connecting element (91) being connected to the rod (6) and the arm (3).

7. The device (1) according to claim 6, characterized in that The energy storage device (92) is configured to retain stored energy when the locking unit (8) is in the engaged configuration (P5), and to release the stored energy when the locking unit (8) is in the free configuration (P6).

8. The device (1) according to claim 6 or claim 7, characterized in that The connecting element (91) comprises at least one rod (91A), which is rotatably connected to the arm (3) and slidably connected to the rod (6) via a restraining element (93), and wherein the energy storage element (92) is a spring (92A), which is arranged on the rod (91A) and acts between the restraining element (93) and one end of the rod.

9. The device (1) according to claim 3, characterized in that The locking unit (8) comprises a second supply device (82A) for supplying energy to the second actuator (82).

10. The device (1) according to claim 4, characterized in that The device (1) comprises a rotating structure (2) with an annular shape, which carries the support device (7) and is movable in a direction of rotation around a first central axis (X1) of rotation.

11. The device (1) according to claim 10, characterized in that The pin (5) between the arm (3) and the rod (6) is integral with the rotating structure (2).

12. The device (1) according to claim 1, characterized in that The first electric actuator (71) is a linear actuator comprising an electric motor and a lead nut and screw system for moving the rod (6).

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