The present invention relates to machines and apparatuses for cutting pipes made of plastics, and in particular it concerns a cutting apparatus arranged for cutting and chamfering pipes made of plastics.

Pipes made of plastics are widely used for the collection, distribution and supply of fluids, for example for the collection of rainwater and wastewater, the distribution of drinking water, fuel gas, etc.

The pipes are generally obtained by continuous extrusion processes in which the plastic material suitably heated and brought to the plastic state is forced through a mould so as to form a continuous tubular element which must be cut in order to originate pipes of desired length. The pipes thus obtained can then be further cut to obtain lengths or shorter sections according to specific needs and applications.

For this purpose, cutting apparatuses are known, so-called cutters, capable of cutting the pipes, that is, of completely sectioning a cylindrical side wall thereof according to a plane transverse to the longitudinal axis of the pipe and obtaining the various lengths. The cut can also include the contextual chamfering of the external sharp edges of the ends of the pieces originated from the cut, i.e. the removal with an inclined cut of the end prism of the aforementioned sharp edges.

Cutting apparatuses are known comprising one or more single-edged tools (single-edged) or so-called knives, rotated around the pipe and movable from the outside towards the inside of the pipe so as to progressively slice and cut the cylindrical side wall of the latter along its entire circumference. The tools are generally mounted on respective supporting arms fixed to a rotating disk or ring for rotating with the latter about an axis coinciding with the longitudinal axis of the pipe and are further mobile along a linear or arched trajectory, to abut and progressively engrave and cut the side wall of the pipe.

A drawback of these known cutting apparatuses is the fact that the knives, by making a continuous cut on the cylindrical side wall of the pipe, generate long and continuous chips which are difficult to suction and which can become twisted around the cutting apparatus parts creating possible malfunctions and still requiring periodic and constant maintenance of the cutting apparatus.

DE 2361405 describes a cutting-off machine comprising a carriage, a rotating cutting head mounted on the carriage and a cutting tool supported by the cutting head and adapted to be moved intermittently and radially with respect to the pipe to be cut by means of a cam and transferor system, when there is a relative rotation between the cam and the cutting head. The carriage is movable on tracks of a frame and comprises a couple of clamps arranged to block the moving pipe coming from an extrusion line. The cutting head is mounted so as to rotate around the pipe and after locking the pipe, the carriage is moved along the frame with the cutting head rotating. The cutting head also comprises a chamfering tool acting radially on the pipe before the cutting tool.

ITRA20120012 describes a cutting and chamfering system for plastic pipes which includes one or more single -pointed tools whose penetration motion in the wall of the pipe being worked has a radial direction and is periodically interrupted and inverted for a suitable stretch with respect to his centripetal verse. The intermittent radial penetration motion of the tool is controlled by a suitably shaped cam which rotates around the axis of the pipe.

US 4111346 describes a pipe cutting machine which comprises a cutting station and means provided with a gripping unit and arranged for intermittently moving a pipe to be cut. The cutting station comprises a cutting head having a central opening and supporting three rotating knives acting radially on the wall of the pipe. The cutting head and the respective driving means comprise means for operating the rotating knives and means for precisely adjusting the radial penetration motion of the knives based on the diameter and thickness of the pipe wall.

An object of the present invention is to improve the known cutting apparatuses for making cuts and chamfers on pipes made of plastics, in particular pipes made of PVC.

Another object is to provide a cutting apparatus that allows precise and regular cuts to be made and capable of generating broken, non-continuous and large-sized chips in the cut, which are therefore more easily suctioned and recyclable for subsequent processing.

A further object is to provide a cutting apparatus capable of generating chips only outside the pipe and not therein.

Still another object is to provide a cutting apparatus having a simple and economic structure and an effective and reliable operation.

These and other objects are achieved by a cutting apparatus according to one or more of the claims set out below.

The invention can be better understood and implemented with reference to the attached drawings which illustrate an exemplifying and non -limiting embodiment thereof, wherein:

Figure 1 is a schematic perspective front view of the cutting apparatus of the invention associated with a pipe made of plastics, represented in a dotted line;

Figure 2 is a front view of the cutting apparatus of Figure 1 which illustrates a supporting disk for a cutting tool, a chamfering tool and a compression tool; Figure 3 is a front view of the cutting apparatus of Figure 2 wherein the supporting disk has been removed to better illustrate an underlying disk for adjusting the movement of the tools;

Figure 4 is a partial enlarged view of the cutting apparatus of Figure 3 which illustrates in particular adjustment means for varying an angular position of the adjustment disk. With reference to Figures 1 to 4, a cutting apparatus 1 according to the invention is shown arranged for making cuts on pipes made of plastics, in particular PVC pipes.

The cutting apparatus 1 comprises a supporting disk 2 rotatable about a rotation axis Z and provided with a central opening 2a for inserting a plastic pipe 100 to be worked in a work configuration L. In this work configuration L the pipe 100 is locked by locking means of the cutting apparatus 1, of a known type and not illustrated, so that a longitudinal axis thereof is substantially coincident with the rotation axis Z of the supporting disk 2. The supporting disk 2 and the locking means are supported by frame means 4 of the cutting apparatus 1, also of a known type.

The cutting apparatus 1 comprises at least one cutting tool 11 supported via first support means 12 by the supporting disk 2 and movable towards the rotation axis Z in order to abut and cut a wall 100a of the pipe 100. The cutting tool 11 is also movable away from the rotation axis Z after the cutting has occurred.

The cutting tool 11 comprises a tool or knife with a single cutting edge (mono-cutting edge) arranged to cut and completely cross the wall 100a of the pipe 100, making a complete cut which originates two pieces of pipe 100. The complete cut performed by the cutting tool 11 is preferably orthogonal to the wall 100a of the pipe 100 and to the rotation axis Z.

The cutting apparatus 1 includes an adjustment disk 3 adjacent to, coaxial to and rotatable with, the supporting disk 2. The adjustment disk 3, which is provided with a respective central opening 3 a for inserting the pipe 100, is also arranged to act by means of first moving means 15 on the cutting tool 11 for moving the latter towards the rotation axis Z when an angular position of the adjustment disk 3 itself around the rotation axis Z with respect to the supporting disk 2 is changed, as better explained in the following description. The adjustment disk 3 is rotatably supported by the frame means 4.

The cutting apparatus 1 comprises driving means 5 for moving the supporting disk 2 and the adjustment disk 3 about the rotation axis Z with rotation motions having the same established revolving speed, which is calculated on the basis of the dimensions of the pipe 100, the characteristics of the plastic material of the latter and the characteristics (shape, size) of the cutting tool 11. Adjustment means 6 are associated with the driving means 5 and arranged for changing the angular position of the adjustment disk 3 and to generate or create an oscillating or vibrating component in the rotation motion of the adjustment disk 3 around the rotation axis Z, so as to move with an linear reciprocating motion the cutting tool 11 when it is moved by the adjustment disk 3 towards the rotation axis Z abutting the wall 100a of the pipe 100, i.e. in the cutting phase.

The driving means 5 comprise, for example, a first driving pulley 51 rotating the supporting disk 2 by means of a first belt 53 (or band or other similar flexible transmission element), and a second driving pulley 52 rotating the adjustment disk 3 by means of a second belt 54 (or band or other similar flexible transmission element); the first driving pulley 51 and the second driving pulley 52 are substantially coaxial and driven by known motor means, not shown in the figures.

The first belt 53 and the second belt 54 are wound around external walls of the supporting disk 2 and of the adjustment disk 3 and comprise, for example, toothed belts which ensure a precise and accurate transmission of the rotation movement; the driving pulleys 51, 52 are similarly toothed.

The adjustment means 6 comprise a couple of adjustment pulleys 7, in particular also toothed, which are fixed to a mobile adjustment carriage 8 and engaged by the second belt 54, in particular the latter being wound on opposite outer sectors 7a of the aforementioned adjustment pulleys 7.

The driving means 5 further comprise a plurality of guiding pulleys 55, for example four, for guiding the second belt 54 wound around the adjustment pulleys 7, in particular for increasing the winding width of the second belt 54 around the outer sectors 7 a of the adjustment pulleys 7.

It is also provided a deflection pulley 56 adjustable in position and arranged for suitably engage and tension the first belt 53 around the supporting disk 2.

The adjustment pulleys 7 are movable with the adjustment carriage 8 along an adjustment direction R in order to move a branch 54a of the second belt 54 which is engaging the adjustment disk 3 so as to rotate the latter by an established angle around the rotation axis Z with respect to said supporting disk 2.

The rotation axes X of the adjustment pulleys 7 are parallel to the rotation axis of the driving pulleys 51, 52 and to the rotation axis Z of the supporting disk 2 and of the adjustment disk

3.

The adjustment carriage 8 is slidably supported by the frame means 4 and is moved by driving means of a known and not illustrated type, along the adjustment direction R, which is almost horizontal and orthogonal to the rotation axis Z.

The adjustment pulleys 7 are eccentrically fixed to the adjustment carriage 8 so as to rotate eccentrically and in phase when moved by the second belt 54 operated by the second driving pulley 52. In particular, as better illustrated in Figure 4, the rotation axis X of each adjustment pulley 7 (coinciding with the axis of a fixing pin 17 of the adjustment pulley 7 to the adjustment carriage 8) is spaced apart by a defined distance e from a respective symmetry axis S of the adjustment pulley 7, this inducing, in the rotation of the adjustment pulleys 7, an oscillating or vibratory component (for example with sinusoidal trend) to the rotation motion of the adjustment disk 3 around the rotation axis Z. This oscillating or vibratory component is transmitted by the adjustment disk 3, through the first moving means 15, to the cutting tool 11 which therefore moves towards the rotation axis Z of the pipe 100, and in particular during the cutting of its side wall 100a, with a forwarding motion having a reciprocating component, that is, with a "percussion" cutting movement which allows the single cutting edge of the cutting tool 11 to fragment and break the plastic chip during cutting.

The first support means 12 of the cutting tool 11 comprise a first supporting arm 13 fixed to the supporting disk 2, in particular to a peripheral edge thereof, and slidingly supporting a first driving slide 14 to which is fixed the cutting tool 11. The first driving slide 14 engages the first moving means 15 of the adjustment disk 3 and movable along a rectilinear trajectory, for example substantially radial with respect to the rotation axis Z. In particular, the first moving means comprise a first shaped slot 15, for example a through shaped slot, carried out on an outermost crown of the adjustment disk 3 and adapted to receive a first guiding roller 16 of the first driving slide 14.

As better explained in the description that follows, the relative rotation of the adjustment disk 3 with respect to the supporting disk 2 causes the movement of the first guiding roller 16 engaged in the first shaped slot 15, i.e. the linear movement of the first driving slide 14 and of the cutting tool 11 along the first supporting arm 13 for performing the cutting of the pipe 100.

In the embodiment shown in the figures, the cutting apparatus 1 of the invention further comprises a chamfering tool 21 supported by the supporting disk 2 via second support means 22 and coupled to the adjustment disk 3 by second moving means 25, so as to be moved towards the rotation axis Z to abut and interact with the wall 100a of the pipe 100 and movable in the opposite direction, away from the rotation axis Z, after the processing. The chamfering tool 21 comprises a respective tool or knife with a single cutting edge suitably shaped, capable of executing externally on the wall 100a of the pipe 100 an annular shaped groove which will give rise to a chamfer on the outer edge of the end of one of two pieces of the pipe 100 made by the complete cut performed by the cutting tool 11.

A compression tool 31 is also provided supported by the supporting disk 2 via third support means 32 and coupled to the adjustment disk 3 by third moving means 35 so as to be moved towards the rotation axis Z so as to abut the wall 100a of the pipe 100, in particular for compressing edges of a cut carried out on the wall 100a by the cutting tool 11. The compression tool 31 can also be moved from the adjustment disk 3 in the opposite direction, away from the rotation axis Z, after processing. The compression tool 31 comprises a roller mounted free to rotate on the third support means 32 and capable of finding and rotating externally on the wall 100a of the pipe 100 by exerting a defined compression force.

The second support means 22 of the chamfering tool 21 and the third support means 32 of the compression tool 31 comprise respectively a second supporting arm 23 and a third supporting arm 33, that are fixed to the supporting disk 2, in particular at a peripheral edge thereof, and slidingly supporting respectively a second driving slide 24 to which the chamfering tool 21 is fixed and a third driving slide 34 to which the compression tool 31 is fixed.

The second driving slide 24 and the third driving slide 34 are engaged respectively to the second moving means 25 and third moving means 35 of the adjustment disk 3 and are movable along rectilinear paths, for example substantially radial with respect to the rotation axis Z. In particular, the second moving means and the third moving means comprise respectively a first and a second shaped slots 25, 35, for example through shaped slots, both made on the outermost crown of the adjustment disk 3. The second shaped slot 25 is adapted to receive a second guiding roller 26 of the second drive slide 24, while the third shaped slot 35 is adapted to receive a third guiding roller 36 of the third driving slide 34.

Also in this case, the relative rotation of the adjustment disk 3 with respect to the supporting disk 2 causes the displacement of the guiding rollers 26, 36 engaged in the second and third shaped slots 25, 35 and therefore the linear displacement of the second driving slide 24 and consequently of the chamfering tool 21 along the second supporting arm 23 and that of the third driving slide 34 and consequently of the compression tool 31 along the third supporting arm 33.

The operation of the cutting apparatus 1 of the invention provides in an initial phase the insertion and locking of the pipe 100 in the work configuration L. The supporting disk 2 and the adjustment disk 3 are therefore rotated about the rotation axis Z at the same predefined working speed by the driving means 5.

During rotation around the rotation axis, in an initial phase, the adjustment disk 3 is positioned with respect to the supporting disk 2 in a first angular position D in which the cutting tool 11, the chamfering tool 21 and the compression tool 31 are more spaced from the pipe 100. In this first angular position D the guiding rollers 16, 26, 36 of the support means 12, 22, 32 of the tools 11, 21, 31 are engaged in an end portion of the respective shaped slots 15, 25, 35 of the adjustment disk 3, closest to the peripheral edge of the latter. The first angular position D of the adjustment disk 3 is obtained by moving the adjustment pulleys 7, i.e. the adjustment carriage 8, in a first external position Cl, i.e. on the left with reference to the front view of Figures 2 and 3.

Subsequently, the adjustment means 6 are operated, in particular the adjustment carriage 8 and the adjustment pulleys 7 are moved in the adjustment direction R so as to progressively change the angular position of the adjustment disk 3 with respect to the supporting disk 2 thus changing also the position of the shaped slots 15, 25, 35 with respect to the guiding rollers 16, 26, 36. The displacement of the shaped slots 15, 25, 35, which substantially act as cams, causes the linear displacement of the guiding slides 14, 24, 34 of the support means 12, 22, 32, i.e. the movement of the tools 11, 21, 31 towards the rotation axis Z and the pipe 100. More precisely, when the adjustment carriage 8 is arranged in a second external position C2, i.e. on the right with reference to the front view of Figure 3, the adjustment disk 3 is rotated with respect to the first angular position D by an angle a (clockwise in Figure 3) in a second angular position (not shown) in which the guiding rollers 16, 26, 36 of the support means 12, 22, 32 of the tools 11, 21, 31 are engaged by an end portion of the respective shaped slots 15, 25, 35 of the adjustment disk 3 further away from the peripheral edge of the latter. This relative rotation (angle a) therefore allows the adjustment disk 3 to move the tools 11, 21, 31 along predetermined working strokes in which the cutting tool 11 is brought into abutment with the wall 100a of the pipe so as to slice and progressively cut the pipe 100 along the entire circumference thereof, the chamfering tool 21 is brought into abutment with the wall 100a so as to penetrate and create an annular shaped groove of established depth which originates the chamfer on the outer edge of the end of one of two pieces of the pipe 100, and the compression tool 5 is brought to abut the wall 100a to press or compress the edges of the cut with a defined compression force while it is being carried out by the cutting tool 11.

The movement of the tools, in particular that of the cutting tool 11, takes place in any case with a forward motion, in particular linear, which comprises a reciprocating component due to the eccentric rotation of the adjustment pulleys 7 of the adjustment means 6 associated with the driving means 5. More precisely, the eccentric rotation in phase of the adjustment pulleys 7 induces in the rotation motion of the adjustment disk 3 an oscillating or vibrating component (for example with a sinusoidal pattern) which is transmitted through the first moving means 15 (i.e. the first shaped slot) to the first support means 12, in particular to the first guiding roller 16 and the first slide 14, and then to the cutting tool 11. The latter is therefore moved linearly towards the rotation axis Z of the pipe 100, also and above all during the cutting of the side wall 100a, with a forward motion that has a reciprocating component, that is with a "percussion" cutting motion or movement. This particular "percussion" movement allows the single cutting edge of the cutting tool 11 to effectively fragment and break the plastic chip that is generated during the cutting, so as to avoid the problems affecting the known cutting apparatus with a single cutting edge.

This operating mode is also applied to the chamfering tool 21 which, thanks to the "percussion" cutting movement, is able to generate fragmented and broken plastic chips of consistent size, i.e. not pulverized, that can be easily suctioned and removed from the work area, in the execution of the annular shaped slot.

The annular shaped slot is carried out by the chamfering tool 21 before the intervention of the cutting tool 11.

Thanks to the cutting apparatus 1 of the invention it is therefore possible to perform precise and regular cuts on pipes made of plastics, in particular of PVC, generating during the cut broken, fragmented, non-continuous material chips, and in any case with consistent size, therefore more easily suctioned and removable from the cutting apparatus and recyclable for following processing.

Furthermore, thanks to the cutting mode of the cutting tool with single cutting edge, the chips are generated only on the outside of the pipe and not on the inside, thus allowing to avoid subsequent complex and expensive cleaning operations inside the pipe.

Due to the adjustment means 6 and the driving means 5 comprising a plurality of pulleys (driving pulleys 51, 52, guiding pulleys 55, adjustment pulleys 7, ...) connected by respective toothed belts 53, 54, the cutting apparatus has a particularly simple and economic structure having efficient and reliable operation.