Apparatus and method for cutting thermoplastic tubing

Abstract

An apparatus for cutting a thermoplastic pipe (T) is described, comprising: at least one guide (2) for movement in a predetermined direction (X); a unit (3) movable along said guide (2) with respect to the predetermined direction (X); a first actuator (5) configured for moving the movable unit (3) along the guide (2), the movable unit (3) comprising: a rotating unit (12) configured to rotate around the thermoplastic pipe (T); a second actuator (6) configured for rotating the rotating unit (12) around the thermoplastic pipe (T); at least one locking unit (20) provided with a clamping element (21) interacting with the pipe (T) and movable between an open configuration and a closed configuration, said clamping element (21) and the rotating unit (12) being coupled to allow the longitudinal blocking of the rotating unit (2) to the pipe in the closed configuration along the predetermined direction (X); a cutting tool (13) carried by the rotating unit (12) for cutting the pipe (T), the cutting tool (13) being configured to move radially with respect to the pipe (T); a third actuator (7) carried by the rotating unit (12) acting on the cutting tool (13) to move it radially with respect to said pipe (T); compression means (15) configured to act on a cutting edge (51, 52) of the pipe (T); means (16) for heating said compression means (15) configured for heating the compression means (15) to a predetermined temperature.

Description

Technical Field

[0001] This invention relates to an apparatus and method for cutting pipes made of thermoplastic materials.

[0002] Thermoplastic tubing is produced through an extrusion process, which begins with material in a plastic state and uses a rotary screw system to force the material through a calibrated die of appropriate shape and size.

[0003] The pipe fitting production facility is called an extrusion production line, which consists of multiple pieces of equipment, each designed for a specific function.

[0004] This facility typically includes cutting equipment, usually located at the end of the production line, configured to cut continuously extruded tubing into segments of specified and predetermined lengths.

[0005] The device includes a cutting unit (with a cutting tool inserted therein) mounted on a movable bracket, which is integrally connected to the extruded tube by means of a clamping device called a clamp during cutting operation.

[0006] Typically, the nature of the cutting action depends on the type of thermoplastic material being cut. Background Technology

[0007] Pipes made from commonly used thermoplastic materials, many of which (such as PVC-U, ABS, and PMMA) exhibit brittle mechanical behavior and exceptionally high hardness. Due to these mechanical characteristics, these materials are typically cut by removing material using a toothed disc or motor-driven grinding wheel. All the disadvantages of this cutting method are well-known in the prior art, including the generation of contaminating powder and chips, which therefore require suction, collection, and treatment.

[0008] Cutting by separating the material (e.g., using a cutting tool) overcomes all the problems associated with cutting by removing the material, but especially in pipes made of the aforementioned materials, the pipes may break during cutting (potentially damaging the tool) if not cut using specific techniques, the final quality of the cut surface may not be good enough, and the cut itself may be unclean and inaccurate.

[0009] In particular, in order to achieve high-quality cutting, it is necessary to ensure that the movement of the cutting tool is perpendicular to the surface of the pipe, which can be achieved by using a tool with sufficient rigidity.

[0010] The rigidity of a cutting tool depends on the shape and thickness of the tool itself.

[0011] According to existing techniques commonly used in cutting materials by separation, increasing the thickness of the cutting tool to improve rigidity can adversely cause lip formation and large deformation on the pipe surface, such as requiring modification of nominal external dimensions.

[0012] However, modifications to the nominal dimensions of the lip and fitting can adversely affect the function of the fitting (e.g., the possibility of effectively connecting it to other components to form a specific network for supplying fluid) and often result in a decline in the quality of the fitting. Summary of the Invention

[0013] It is believed that the aforementioned technical deficiencies need to be overcome, particularly to ensure that the fittings maintain their dimensions and integrity even downstream of the cutting action (especially for fittings made of thermoplastic materials with brittle mechanical behavior and particularly high hardness).

[0014] The purpose of this invention is to meet the above-mentioned needs by providing a cutting device and method that allows cutting thermoplastic tubing while maintaining the original dimensions and functionality of the tubing. Attached Figure Description

[0015] The technical features of the present invention are clearly described below with reference to the claims and the accompanying drawings. Its advantages are apparent from the following detailed description. The drawings provide preferred embodiments of the invention by way of example only and do not limit the scope of the inventive concept. In the drawings:

[0016] - Figure 1 This is a schematic perspective view of an apparatus for cutting thermoplastic tubular fittings according to the present invention;

[0017] - Figure 2 This is a perspective view showing details of an apparatus for cutting thermoplastic tubular components according to the present invention;

[0018] - Figure 3 and Figure 4 yes Figure 1 A cross-sectional view of an embodiment of the cutting tool of the cutting equipment;

[0019] - Figure 5 and Figure 6 This is a perspective view of an embodiment of the compression device of the cutting equipment;

[0020] - Figure 7 yes Figure 5 A schematic cross-sectional view of the compression device in an embodiment. Detailed Implementation

[0021] Referring to the accompanying drawings, the number 1 indicates a device for cutting pipe fittings T made of thermoplastic materials (e.g., pipe fittings T made of PVC).

[0022] Other thermoplastic materials used to manufacture pipe fittings T are, for example, PE, PP, PB, ABS, and PMMA.

[0023] The pipe fitting T extends along a predetermined direction X and has an axis A.

[0024] According to one aspect, the cutting device 1 includes at least one guide 2 for moving along a predetermined direction X.

[0025] The device 1 includes a unit 3 that is movable along the guide 2 and moves relative to a predetermined direction X.

[0026] The device 1 includes a first actuator 5 configured to move a movable unit 3 along a guide 2.

[0027] Actuator 5 is preferably an electric actuator.

[0028] According to other examples, actuator 5 is of the pneumatic or hydraulic type.

[0029] The movable unit 3 includes a bracket 11, which is allowed to move in a predetermined direction X due to the actuator 5.

[0030] The movable unit 3 includes at least one locking unit 20, which is equipped with a clamping element 21 that interacts with the pipe fitting T.

[0031] The clamping element 21 is movable between the open and closed configurations.

[0032] The clamping element may be, for example, a jaw (the aforementioned clamp) that allows the tube X to be locked relative to the movable unit 3.

[0033] The movable unit 3 includes a receiving body 30 connected to the bracket 11.

[0034] like Figure 1 As shown, the main body 30 of the movable unit 3 is passed through the pipe T that must be cut.

[0035] The movable unit 3 includes a rotating unit 12 configured to rotate about the pipe T.

[0036] The rotating unit 12 is positioned inside the housing body 30.

[0037] According to, for example Figure 2 In the embodiment shown, the rotating unit 2 includes a pair of annular elements 12A and 12B connected by a plurality of longitudinal rods 12C.

[0038] The clamping element 21 and the rotating unit 12 are connected in such a way that, in the closed configuration, the rotating unit 12 is allowed to be longitudinally constrained to the tube T along a predetermined direction X.

[0039] Therefore, the rotating unit 12 can rotate relative to the locking unit 20 about the direction X. However, during the cutting of the pipe T, the rotating unit 12 is constrained to the pipe T in the direction X, that is, along the guide 2.

[0040] The movable unit 3 includes a second actuator 6 configured to rotate the rotating unit 12 about the tube T.

[0041] The movable unit 3 includes a cutting tool 13 for cutting on the pipe T, carried by the rotating unit 12.

[0042] The rotating unit 12 serves as the support body for the cutting tool 13.

[0043] The movable unit 3 includes a third actuator 7, which is carried by the rotating unit 12 and runs on the cutting tool 13 to move the tool 13 radially relative to the pipe T.

[0044] Therefore, actuator 7 allows cutting tool 13 to move from a first position where tool 13 is not in contact with pipe T to a second position where tool 13 is fully submerged in pipe T for cutting.

[0045] Therefore, the cutting tool 13 is configured to move radially relative to the pipe fitting T.

[0046] Tool 13 rotates around axis A of pipe fitting T and simultaneously plunges radially into pipe fitting T to make cuts.

[0047] In fact, since the tool 13 is supported by the rotating unit 12, when the rotating unit 12 rotates about axis A, the tool 13 rotates about axis A of the pipe T.

[0048] Then, using tool 13, the pipe fitting T is cut into two sections, T1 and T2, which have edges 51 and 52 respectively.

[0049] according to Figure 3 In the embodiment shown, the cutting tool 13 is a rotary disc blade that rotates about the rotation axis A2.

[0050] In other words, tool 13 is preferably an idle disc blade.

[0051] according to Figure 4 In the embodiment shown, the cutting tool 13 is a blade.

[0052] The movable unit 3 also includes a power transmission device, preferably of the slip ring type, which allows power and signals to be transmitted to the rotating unit 12, thereby allowing the operation of the third actuator 7.

[0053] The movable unit 3 includes a compression device 15 configured to act on the cut edge of the pipe fitting T.

[0054] The compression device 15 allows the cutting edge to be subjected to mechanical action, i.e., local deformation, thereby essentially eliminating any deformation caused by the cutting action.

[0055] Specifically, the compression device 15 is configured to act on each cut edge 51, 52 of the pipe fitting T.

[0056] It should be noted that the compression device 15 acts simultaneously on both the end of the pipe section being cut and the end of the continuous pipe section upstream of the aforementioned section during the cutting process relative to the compression direction.

[0057] Preferably, the compression device 15 is associated with and next to the cutting tool 13.

[0058] In other words, according to the preferred embodiment, the compression device 15 is positioned on opposite sides of the cutting tool 13.

[0059] according to Figure 5 and Figure 7 With the aid of the illustrated embodiment, the compression device 15 includes a flange 18.

[0060] according to Figure 7 In the embodiment shown, the compression device 15, particularly the flange 18, includes a first flange 18A and a second flange 18B.

[0061] The first flange 18A acts on the segment edge 51 of the pipe fitting T1, while the second flange 18B acts on the cut end of the pipe fitting T2 upstream of the aforementioned segment relative to the extrusion direction.

[0062] Each flange 18 preferably has a truncated conical shape, with the larger base face facing the cutting tool 13.

[0063] The movable unit 3 includes a heating device 16 configured to heat the compressor 15 to a predetermined temperature.

[0064] Depending on the type of thermoplastic material of the fitting T, the compression device 15 is heated to a temperature preferably between 50° and 200°.

[0065] Advantageously, the heating device and the compression device 15 facilitate the compression of the deformation and lip movement caused by the cutting action.

[0066] Preferably, the heating device 16 includes a fixed heating body 17.

[0067] According to the example, the fixed heating body 17 transfers heat to the compression device 15 through sliding contact.

[0068] In this case, the compression device 15, especially the flange 18, is heated by conduction.

[0069] Each fixed body 17 is continuously placed on the outer surface of the corresponding flange 18.

[0070] According to one embodiment, a fixed body 17 is connected to a flange 18 and configured to heat the flange 18 to a predetermined temperature.

[0071] According to one embodiment, each fixed body 17 includes a resistor 19 for determining heating.

[0072] According to one embodiment, the compression device 15 includes a support element 40 configured to also support the cutting tool 13.

[0073] According to one embodiment, the compression device 15 includes an external compression element 41 supported by a support element 40.

[0074] Preferably, the compression element 41 is an idle roller that rotates about its own axis.

[0075] According to one example, element 41 is heated by a suitable heating device (not shown).

[0076] The heated compression element 41 contacts and compresses the edges 51, 52 of the cut pipe to eliminate the lip caused by the cutting action and restore the original size of the pipe T.

[0077] According to another aspect, the support element 40 includes a contact device configured to maintain the compression element 41 in contact with the surface of the tube T during cutting.

[0078] Preferably, the contacting device includes one or more elastic elements, such as springs, which apply an elastic action (preferably by compression) to the compression element 41.

[0079] According to one embodiment, for example Figure 6 As shown, the compression device 15 includes a compression element 41 and a flange 18.

[0080] According to this embodiment, the compression element 41 works simultaneously with the heated flange 18 at different portions of the edges 51, 52 of the pipe.

[0081] Generally, the flange 18 and / or the compression element 41 can be heated by conduction (by means of a fixed body—shown and indicated as 17 for the flange 18—which transfers heat to them), or, in an example not shown, the compression device 15 can be heated by induction or by radiation.

[0082] If the compression device 15 is heated by induction, the device 15 includes a ferromagnetic material, and the rotating unit 12 includes at least one induction coil configured to generate electromagnetic induction on the compression device 15.

[0083] The cutting tool 13 rolls while the heated flange 18 is forced into contact with the surface of the pipe T, and deforms by compression of the cut itself if necessary. With mechanical and thermal action, the pipe undergoes deformation after the cutting action and returns to the original size of the pipe T before it was cut at the edge.

[0084] As mentioned above, in order to ensure good cutting quality, the cutting plane must always be perpendicular to the axis A of the pipe fitting T.

[0085] Therefore, the axial stiffness of the cutting tool 13 is crucial to prevent it from bending during the penetration action and transforming into a non-perpendicular cutting plane.

[0086] This is especially important for pipe fittings made of thermoplastic materials such as PVC-U, ABS, and PMMA, which exhibit fragile mechanical behavior and particularly high hardness.

[0087] However, as mentioned above, the stiffness of the cutting tool 13 is closely related to its thickness.

[0088] According to the embodiment of the cutting tool 13, without minimum stiffness, it is impossible to go below the limit thickness value of the tool 13 to prevent non-perpendicular cutting and / or premature breakage of the tool 13.

[0089] It should also be considered that the thickness of the cutting tool 13 determines the degree of deformation caused on the pipe T and the size of the resulting lip.

[0090] Therefore, in order to improve the rigidity of tool 13, increasing the thickness of tool 13 will result in greater lip and deformation of pipe T.

[0091] Using the idle disc cutting tool 13 advantageously allows for limiting deformation and reducing the range of the lip.

[0092] Advantageously, the disc shape of the cutting tool 13 relative to the blade allows it to effectively reduce its thickness (with the same bending stiffness), thereby significantly limiting unwanted expansion and lip formation at the cutting plane of the pipe T.

[0093] In this case, the cutting action includes the radial feed motion and rotation of tool 13 about axis A of pipe T, just like a normal cutting blade, as well as the rotational motion of the disc tool about the corresponding axis A2.

[0094] The friction generated between the disc cutting tool 13 and the surface of the pipe T is rolling, all of which have the advantage of reducing coercive forces on the material of the pipe T during penetration.

[0095] However, it should be noted that using a thin disc blade can reduce but not eliminate the deformation effect (e.g., curling) on ​​the surface of the pipe T caused by the penetration of the cutting tool 13.

[0096] In this case, during the final step of the cutting process, the heated compression device 15 (in the form of flange 18 and / or compression element 41) further acts on the surface of the tube T to mechanically and thermally recompress any lip and expansion produced by the cutting tool 13.

[0097] According to a preferred embodiment, the rotating unit 12 includes at least one temperature sensor 30 configured to measure temperature values ​​and generate a signal S1 representing the temperature value of the heating device 16.

[0098] It should be noted that the heating device 16 brings the compression device 15 to a predetermined temperature, therefore monitoring the temperature of the heating device 16 is crucial.

[0099] The device includes at least a control unit U that communicates with a temperature sensor 30 and a heating device 16, such as Figure 5 and Figure 6 As shown in the image.

[0100] The control unit U is configured to receive signal S1 and control the heating device 16 according to signal S1.

[0101] In other words, unit U receives signal S1 from sensor 30 and controls the operating temperature of heating device 16 based on the signal, such as controlling the start-up or adjusting the power.

[0102] Controlling the operating temperature of the heating device 16 indirectly relates to controlling the temperature of the flange 18.

[0103] In fact, the temperature sensor 30, combined with the unit U, advantageously allows the heating device 16 to be maintained at a predetermined temperature.

[0104] Preferably, the temperature sensor 30 is a thermocouple.

[0105] According to another embodiment not shown, the temperature sensor 30 uses, for example, a pyrometer-type sensor to directly measure the temperature of the compression device 15.

[0106] According to one aspect, the present invention relates to a method for cutting thermoplastic tubular fittings T.

[0107] The method includes the following steps:

[0108] - Lock the thermoplastic fitting T along the first direction.

[0109] -Prepare the cutting tool 13 and the compression device 15 associated with the cutting tool 13.

[0110] - Move the cutting tool 13 radially relative to the thermoplastic pipe fitting T, and rotate the cutting tool 13 about the axis A of the thermoplastic pipe fitting T to cut the thermoplastic pipe fitting T.

[0111] -Heat the compression device 15 associated with the cutting tool 13 to a predetermined temperature.

[0112] - A heated compression device 15 rotates about axis A of the pipe fitting T to compress the edges 51, 52 of the cut pipe fitting.

[0113] The terms "edges 51, 52 of the cut fitting" refer to the edges of the fitting T at the point where the cut is made.

[0114] Advantageously, the heated compression device 15 enables it to compress better and eliminate the lip caused by the cutting of the pipe fitting T, restoring the integrity of the edge and the original size of the pipe fitting.

[0115] According to one embodiment, the method includes the step of heating the compression device 15 by radiation or magnetic induction.

[0116] According to one embodiment, the method includes the steps of preparing a compression device 15 including a flange 18 and heating the flange 18 to a predetermined temperature.

[0117] Preferably, the step of heating the flange 18 to a predetermined temperature includes heating the flange 18 to a temperature preferably between 50° and 200° depending on the type of thermoplastic material of the pipe fitting T.

[0118] Advantageously, the heated compression device 18 enables it to compress better and eliminates the lip caused by the cutting of the pipe fitting T, restoring the integrity of the pipe fitting's edge.

[0119] According to one embodiment, the method includes the step of preparing a heating device 16 connected to a compression device 15.

[0120] The step of heating the compression device 15 associated with the cutting tool 13 to a predetermined temperature includes activating the heating device 16 to heat the compression device 15 to the predetermined temperature.

[0121] According to one embodiment, the step of preparing the heating device 16 includes preparing a fixed heating body 17 connected to the flange 18 to transfer heat by conduction.

[0122] The step of heating the flange 18 to a predetermined temperature includes sliding the flange 18 and the fixed heating body 17.

[0123] Advantageously, the sliding flange 18 and the fixed heating body 17 allow the flange 18 to be heated by conduction, so that heat can be transferred from the fixed heating body 17 to the flange 18.

[0124] According to one embodiment, the step of preparing the compression device 15 includes the step of preparing the compression element 41.

[0125] According to one embodiment, the method includes the step of rotating a compression element 41 about the axis A of the pipe T to compress the edges 51, 52 of the cut pipe T.

[0126] According to one embodiment, the step of rotating the heated compression device 15 for compressing the edges 51, 52 of the cut pipe T about the axis of the pipe includes simultaneously rotating the flange 18 about the axis A of the pipe to compress the first edge portions 51A, 52A of the cut pipe, and simultaneously rotating the compression element 41 about the axis A of the pipe T to further compress the edges 51, 52 of the cut pipe T at the second edge portions 51B, 52B.

[0127] Therefore, in short, the cutting tool 13 with heated compression device 15 significantly improves the cutting quality by separating the material of the pipe fitting T, effectively eliminating the limitations of cutting by separating the material (which advantageously does not generate dust and chips), i.e., the pipe fitting T produces a lip and deformation on the surface at the cutting plane, especially for thermoplastic pipe fittings with brittle behavior but high hardness.

Claims

1. An apparatus for cutting a thermoplastic pipe (T), comprising: - at least one guide (2) for movement in a predetermined direction (X); - a movable unit (3) movable along the guide (2) with respect to the predetermined direction (X); - a first actuator (5) configured for moving the movable unit (3) along the guide (2), the movable unit (3) comprising: - a rotating unit (12) configured to rotate around the thermoplastic pipe (T); - a second actuator (6) configured for rotating the rotating unit (12) around the thermoplastic pipe (T); - at least one locking unit (20) provided with a clamping element (21) interacting with the thermoplastic pipe (T) and movable between an open configuration and a closed configuration, the clamping element (21) and the rotating unit (12) being coupled to allow longitudinal constraint of the rotating unit (12) to the pipe in the closed configuration along the predetermined direction (X); - a cutting tool (13) carried by the rotating unit (12) for cutting the thermoplastic pipe (T), the cutting tool (13) being configured to move radially with respect to the thermoplastic pipe (T); - a third actuator (7) carried by the rotating unit (12) acting on the cutting tool (13) to move it radially with respect to the thermoplastic pipe (T); - compression means (15) configured to mechanically act on the cutting edge (51, 52) of the thermoplastic pipe (T), i.e. to locally deform it, thus substantially eliminating any deformation caused by the cutting action; heating means (16) for heating the compression means (15), configured for heating the compression means (15) to a predetermined temperature.

2. The apparatus of claim 1, wherein, The compression means (15) are associated with the cutting tool (13) and placed alongside the cutting tool (13).

3. The apparatus of claim 1 or 2, wherein, The compression means (15) comprise flanges (18).

4. The apparatus of claim 3, wherein, Each flange (18) has a truncated conical shape, with a larger base facing the cutting tool (13).

5. The apparatus of claim 1, wherein, The compression means (15) comprise a support element (40) configured to support the cutting tool (13).

6. The apparatus of claim 5, wherein, The compression means (15) comprise a compression element (41) supported by the support element (40).

7. The apparatus of claim 3, wherein, The heating means (16) comprise fixed heating bodies (17) coupled to the flanges (18) and configured for heating the flanges (18) to a predetermined temperature.

8. The apparatus of claim 7, wherein, The fixed heating bodies (17) are configured for heating the flanges (18) by conduction.

9. The apparatus of claim 7 or 8, wherein, Each fixed heating body (17) comprises an electric resistance (19).

10. The apparatus of claim 1, wherein, The device comprises a temperature sensor (30) configured to measure a temperature value and to generate a signal (SI) representative of said temperature value, the device comprising a control unit (U) in communication with at least said temperature sensor (30) and with said heating means (16), said control unit (U) being configured to receive said signal (SI) and to control said heating means (16) as a function of said signal (SI).

11. The apparatus of claim 1, wherein, The cutting tool (13) is an idle disc blade.

12. A method for cutting a thermoplastic tubular piece (T), comprising the steps of: - locking the thermoplastic tubular piece (T) in a first direction, - preparing a cutting tool (13) and compression means (15) associated with said cutting tool (13) for a mechanical action, i.e. to locally deform the cutting edge of the thermoplastic tubular piece (T), - moving the cutting tool (13) radially with respect to the thermoplastic tubular piece (T) and rotating the cutting tool (13) around the axis (A) of the thermoplastic tubular piece (T) to cut the thermoplastic tubular piece (T), - heating the compression means (15) associated with the cutting tool (13) to a predetermined temperature, - rotating the heated compression means (15) around the axis (A) of the tubular piece to deform the edge (51, 52) of the thermoplastic tubular piece (T) being cut, thus eliminating any deformation caused by the cutting action.

13. The method of claim 12, wherein, The method comprises the steps of preparing the compression means (15) comprising a flange (18) and heating the flange (18) to a predetermined temperature.

14. The method of claim 13, wherein, The method comprises the step of preparing a heating means (16) coupled with the compression means (15), the step of heating the compression means (15) associated with the cutting tool (13) to a predetermined temperature comprising the step of activating the heating means (16) to heat the compression means (15) to a predetermined temperature.

15. The method of claim 14, wherein, The step of preparing the heating means (16) comprises the step of preparing a fixed heating body (17) coupled to the flange (18) to transfer heat by conduction, the step of heating the flange (18) to a predetermined temperature comprising the step of sliding the flange (18) and the fixed heating body to allow the transfer of heat from the fixed heating body to the flange (18).

16. The method according to any one of claims 13 to 15, characterized in that, The step of preparing the compression means (15) comprises the step of preparing a compression element (41) associated with a support element (40) operatively connected to the cutting tool (13).

17. The method of claim 16, wherein, The step of rotating the heated compression means (15) around the axis (A) of the tubular piece to deform the edge (51, 52) of the thermoplastic tubular piece (T) comprises the step of rotating the heated compression element (41) around the axis (A) of the tubular piece to compress the edge (51, 52) of the tubular piece (T) being cut.

18. The method of claim 16, wherein, The step of deforming the edges (51, 52) of the hot plastic tube (T) being cut by rotating the heated compression device (15) around the axis of the tube to compress the edges (51, 52) of the tube being cut comprises the step of rotating the flange (18) around the axis (A) of the tube to compress a first edge portion (51, 52) of the tube being cut and the step of rotating the compression element (41) around the axis (A) of the hot plastic tube (T) to further compress the edges (51, 52) of the hot plastic tube (T) being cut at a second edge portion (51, 52) of the hot plastic tube (T) being cut.

19. The method of any one of claims 13-15, wherein, The step of preparing the cutting tool (13) and the compression device (15) associated with the cutting tool (13) comprises the step of preparing an idle disc-type cutting tool (13).

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