The invention relates to an apparatus for machining, especially for beveling and straightening the end of a tubular or round bar type piece.

PRIOR ART

The prior art discloses a variety of tools for machining, such as for beveling the end of a tubular or round bar type piece. One exemplary prior known tool is the angle grinder, comprising a rotating disc capable of beveling the end of a piece.

A problem with such equipment is, among others, the absence of adequate support, which makes beveling particularly inconvenient. Often, the beveling result is not smooth, thus resulting in a possible leakage point for example in the pipe system either by its raggedness or with sharp cutting edges damaging pipe seals in a pipe installation process.

The prior art also discloses devices, seeking to eliminate some of the above- mentioned problems. For example, publication EP 0152659 describes a solution which enables trimming the ends of two different-sized pipes. In addition, publications GB 2245516 and WO 2006/119548 disclose other solutions for beveling the end of a plastic pipe.

A problem with the foregoing solutions is, however, that these only enable operating pipes of a specific size in terms of their diameter and/or wall thickness. What makes this especially problematic is the fact that the critical dimension of a pipe to be machined is explicitly its outer diameter, whereby, when its diameter is even slightly too large, the pipe does not fit inside the machining unit and, alternatively, when its diameter is too small, the pipe is loose and the desired machining work cannot be performed. In addition, the solution presented in EP 0152659, among others, is highly critical regarding the wall thickness of a pipe to be machined, because the pipe should fit within guide walls. Still further, the solution presented in WO 2006/119548, among others, does not enable beveling or straightening the ends of solid pipes. SUMMARY

One objective of the invention is to eliminate or at least mitigate drawbacks related to the prior art. According to one embodiment, the invention seeks to provide such an apparatus for machining a tubular or round bar type piece, particularly for beveling and straightening its end, wherein one and the same apparatus enables the convenient, safe and quick machining of tubular pieces varying in sizes as regards their diameters and/or wall thicknesses.

Some objectives of the invention are achieved with an apparatus as set forth in claim 1. The apparatus according to the invention is characterized by what has been presented in claim 1 directed to an apparatus.

According to a first embodiment of the invention, the apparatus for machining a tubular or round bar type piece, such as for example for beveling and/or straightening the end of a piece, comprises a frame element, as well as support elements associated with the frame element, and a tool member, such as for example a blade, associated with at least one support element. According to the invention, the support elements are adapted to be radially movable relative to the frame element towards the frame element's rotation axis, i.e. approaching each other, and away from the rotation axis, i.e. drawing away from each other. The frame element has a groove for enabling said radial movement for each support element in radial direction.

In order to work on a piece, the support elements can be extended for example to their extreme positions to set the same as far apart as possible, after which the apparatus can be placed around the end of a work object, for example a plastic pipe. This is followed by moving the support elements preferably towards the frame element's rotation axis, such that the support elements touch a surface of the workpiece, thus supporting the apparatus around the piece in a rotatable manner, whereby the tool member becomes preferably adapted to touch the workpiece at an angle and to perform the machining operation as said frame element is rotated axially around said frame element's rotation axis. It should be noted that, according to one embodiment, the angle of a tool member can be changed and tool members can be replaceable or double-sided to turn the same over upon wearing. According to one preferred embodiment, the support elements are adapted to be movable simultaneously towards the frame element's rotation axis (approaching) or away from the same (drawing away). Most preferably, when moving for example one support element, or an element used for adjusting the support element (such as a guide element described in this document), all support elements are moving simultaneously in an interdependent manner either towards or away from the rotation axis. This enables an easy and quick installation of the apparatus symmetrically around a round bar type workpiece regardless of its diameter size or the wall thickness of a pipe, for example in such a way that the apparatus has its rotation axis and the round bar type piece has its longitudinal axis substantially coinciding, thus being able to hold the apparatus around the piece while working on the latter and to provide a cutting result which is symmetrical and even.

According to one preferred embodiment of the invention, the apparatus further comprises also a guide element associated with the frame element for guiding the support elements with respect to the frame element, for example in the process of adjusting a distance of the support elements from the frame element's rotation axis. The guide element has preferably grooves, along which the support elements are adapted to be radially movable relative to the frame element towards the frame element's rotation axis (approaching) and away from the same (drawing away). According to one preferred embodiment, the grooves are arcuate in terms of their geometry, the support elements being provided on the apparatus so as to slide not only along the frame element's radially extending grooves but also along the guide element's arcuate grooves. Thus, for example, upon turning the guide element axially relative to said frame element and, at the same time, the guide element's rotation axis, the support elements travel along the guide element's arcuate grooves, thereby conducting, relative to the frame element's rotation axis and depending on which way the guide element is being turned, either an approaching or drawing away motion in the frame element's radial direction. Said embodiment provides a very high speed, high precision and convenient way of adjusting the support elements symmetrically around a workpiece, most preferably for example with a single wrist movement. In addition, there is no need to know beforehand or at all the exact diameter or wall thickness of a piece, because the adjustment can be conducted by placing the apparatus directly around the piece and by converging the support elements for a movable contact with the surface of the piece. It is also possible that the apparatus, for example the frame element, be provided with a measurement scale arranged to enable adjusting the support elements by means of the measurement scale to comply directly with a piece of certain size.

According to one embodiment, the support element comprises preferably a wheel or roller, which is adapted to be rotatable around its axis and which is adapted to slide or roll along the surface of a piece as the latter is worked on. It should be noted that the wheel or roller serving as a support element is most preferably adapted to touch an outer surface of the workpiece, but, according to a principle of the invention, especially in the process of machining hollow tubular pieces, the wheel or roller serving as a support element can also be brought to contact with an internal surface of the piece.

According to one embodiment of the invention, the apparatus comprises also a second tool member for straightening the end of a piece as said frame element is rotated axially around the frame element's rotation axis. The second tool member or blade can be arranged for example in connection with the support element in such a way that, when adapting said support element to comply with the dimensions of a workpiece, said second tool member is preferably carried along with the support element to an optimal position.

According to a preferred embodiment of the invention, the apparatus comprises at least three support elements, already providing adequate support for the apparatus rotating around a workpiece during the machining operation. Even more preferably, the number of support elements is four, providing a higher quality support and steadiness of rotation around a piece. The number of support elements can be even higher than what has been described here. It should be noted that the apparatus has at least one tool member, but that each support element may also be provided with at least one tool member either for beveling the end of a piece at its external surface and/or with at least one second tool member for straightening the end of a piece.

The apparatus comprises preferably also clamping means for securing the support elements in said lateral direction of the frame element, such that said elements would support the apparatus through the entire machining process instead of sliding, for example in response to centrifugal force, to an outer periphery of the frame element. The clamping means can be implemented for example by a wing nut associated with each support element or by a clamping element common to the support elements, such as by a rotatably lockable and releasable clamping ring. Furthermore, according to one embodiment, the clamping means can be implemented by means of a friction brake type clamping element, wherein the friction brake can be released for the duration of moving the support elements and then engaged for securing the support elements in position. The friction brake type clamping element can be implemented for example by friction surfaces between the support elements and the frame element or between other such surfaces, the relative friction force thereof being adjustable for engaging and releasing the friction brake. However, it should be appreciated that the apparatus according to the invention also enables the use of other types of clamping mechanisms, such as for example cotter pins or a ratchet system, which enable securing the clamping means at a desired spot for the duration of a machining process as opposed to sliding off for example as a result of centrifugal force.

Still furthermore, the frame element and the guide element are composed of most preferably co-directional planar components with a common rotation axis. In addition, between said frame element and guide element can be provided most preferably a planar guard component for blocking the access of cuttings between the frame element and the guide element. The guard component is also provided with grooves, along which the support elements are adapted to travel upon rotating the guide element axially with respect to the rotation axis of the frame element and the guide element. According to one preferred embodiment, the guard component's grooves are arcuate in terms of their, geometry. As said guard component's arcuate grooves are set to curve in a direction opposite to the corresponding guide element's grooves or at least diverging from the guide element's grooves, the result is a maximal protection effect for blocking the cuttings, because, at any time in the direction of the frame element's rotation axis there is a hole only in that particular location at which the support element extends across both the frame element's groove, guide element's groove and the guard component's groove.

DESCRIPTION OF FIGURES Preferred embodiments of the invention will be described slightly more accurately in the following section with reference to the accompanying figures, in which fig. 1 shows in an axial direction one exemplary apparatus for machining according to one preferred embodiment of the invention, fig. 2 shows in a lateral view one exemplary apparatus for machining according to one preferred embodiment of the invention, and fig. 3 shows a perspective view of one exemplary apparatus according to one preferred embodiment of the invention. DETAILED DESCRIPTION OF FIGURES

Fig. 1 shows, in an axial direction of the apparatus, one exemplary apparatus 100 for machining the end of a tubular or round bar type piece, fig. 2 in a lateral view, and fig. 3 in an exploded view, in accordance with one preferred embodiment of the invention. The apparatus 100 comprises a frame element 101 , as well as support elements 102 in association with the frame element, and a tool member 103 associated with at least one support element. The frame element is provided with a groove 104 for enabling a radial movement of the tool member 103 in a radial direction 105 of the frame element. In order to work on a piece, the support elements can be extended for example to their extreme positions, as shown in fig. 1 , after which the apparatus can be placed around a workpiece 106 and the support elements 102 can be moved towards a rotation axis 107 of the frame element, as shown in fig. 2, such that the support elements 102 touch a surface of the workpiece, such as its external surface, thus supporting the apparatus 100 around the piece 106 in a rotatable manner. Hence, the tool member 103 becomes preferably adapted to touch the workpiece at an angle and to perform the machining operation as the apparatus 100 is rotated around the workpiece relative to the longitudinal axis 107 of the piece 106. Also, the apparatus 100 may further comprise a guide element 108 for guiding the support elements 102 relative to the frame element 101 , for example when adjusting a distance of the support elements from the frame element's rotation axis 107. The guide element has preferably grooves 109, along which the support elements 102 are adapted to be radially 105 movable with respect to the frame element 101 towards the frame element's rotation axis 107 (approaching) and away from the same (drawing away). The movement is most preferably stepless and continuous. According to one embodiment, the support element 102 involves a wheel 102a or a roller, which is preferably adapted for rotation around its axis and which is adapted to slide or roll along a surface of the piece 106 in its machining process. It should be noted that, according to one embodiment, the wheel 102a can be a wheel or roller elongated in the direction of its rotation axis for more firmly supporting the apparatus around a workpiece.

The apparatus 100 may comprise also a second tool member 110 for straightening the end of the piece 106 while rotating said frame element 101 axially around its rotation axis 107. The second tool member 110 or blade can be arranged for example in the engagement with the support element 102 in such a way that also said second tool member is preferably carried along with the support element when the support element is moved. Straightening is a necessary operation for example in the event of a workpiece having been cut in such a way that its end is ragged, uneven or otherwise skew. The apparatus 100 comprises preferably also clamping means 111 for securing the support elements 102 in the radial direction 105 of the frame element 101. The clamping means can be implemented for example by a wing nut associated with each support element or by a clamping element 111 common for the support elements, for example by a rotatably lockabje and releasable locking ring 111. Other optional or additional clamping solutions have been described elsewhere in this document.

It should be appreciated that, according to one preferred embodiment of the invention, the support elements 102 are arranged asymmetrically with respect to the radial groove 104 of the frame element 101 , for example such that a part of the support element 102 in touch with the workpiece 106, for example the wheel 102a, lies in the frame element's rotating direction behind the radial groove 104, whereby a torque applied by the workpiece 106 to the tool members 103, 110 can be more easily managed, nor are the support elements 102 able to disengage or become pried out of the grooves 104, 110 of the frame element 101 and the guide element 108.

Described above are just a few embodiments for a solution of the invention. The principle according to the invention can naturally be varied within the scope of protection defined by the claims, regarding, for example, implementation details and fields of use. The apparatus according to the invention is particularly advantageous for example for beveling and straightening the ends of plastic pipes, and especially beneficial the apparatus is as a manually operated implement, in which case it can be attached for example to the chuck of a prior known drilling machine. However, it should be appreciated that, according to the inventive idea, the apparatus may also constitute part of a larger mechanism, whereby the apparatus enables beveling and/or straightening also meta! bodies, depending on which material the apparatus' tool members are made of.