Patent Application
20140178143
The invention relates to an abutment structure for a workpiece to be machined in a milling machine to achieve accurate positioning of the workpiece during the machining.
The milling machine is a machine tool with a rotating cutter by which material is machined, i.e. removed, from the workpiece to provide a desired shape. Normally, the workpiece is kept stationary and the cutter of the milling machine is moved in different directions to achieve the desired shape of the workpiece.
In particular in manufacturing series, i.e. a number of completely identical pieces, successively by a single milling machine, the workpieces must be accurately positioned in the same place for the duration of the machining to become identical. This is not a problem in large series, as it is easy to build the milling machine with almost fixed support structures that can be kept in their position for long periods. However, in manufacturing small series with an equivalent need to make all parts of the series identical, the problem is to build for workpieces a support abutment that determines the precise position of the workpiece but can be easily removed and changed and shaped in a manner as required by shapes of the pieces in the next series.
The objective of the invention is to remedy the above-mentioned defects of prior art. In particular, the objective of the invention is to disclose a novel workpiece abutment structure for a milling machine, allowing one quickly and easily to modify and change the abutments used and providing unlimited possibilities to form different-sized and different-shaped abutment surfaces.
The invention relates to an abutment structure for a workpiece to be machined in a milling machine, enabling accurate positioning of the workpiece for the duration of the machining. The abutment structure according to the invention includes a body element to be supported to a bench of the milling machine and a number of support elements shaped as a rectangular parallelepiped and mountable to one another in a superposed configuration as a support post of a desired height. The number of the support elements may vary case-specifically, always according to the size of the workpiece. Further, the abutment structure includes a number of straight abutment bars and corresponding support holes and lockings in the support elements. Thus, a suitable number, one or more abutment bars can be pushed through the support element or support elements and locked in a desired position in such a way that ends of the abutment bars form accurate support points against which a workpiece to be positioned is closely supported. In addition, the abutment structure according to the invention has a locking bar and a corresponding hole in each support element in such a way that the support elements can be locked to one another as a support post of a desired height.
The support element shaped as a rectangular parallelepiped includes six faces, i.e. an upper surface, lower surface, two lateral surfaces and two end surfaces.
Thus, the support holes are arranged to extend straight through the support element from one end surface to the other. Preferably, one support element has a number of superposed and parallel support holes extending from one end surface to the other through the support element. Thus, it is possible to support an abutment bar at a different height in one support element as needed or to support a number of abutment bars in the same support element.
Locking in place of the abutment bar is carried out simply by an arrangement extending perpendicularly into the support hole from a lateral surface of the support element, wherein a locking screw can be turned onto the abutment bar in the hole. In a preferred embodiment of the invention, the locking screw does not, however, come into contact with the abutment bar; instead, a locking plug is provided in the hole for the locking screw between same and the abutment bar. The locking plug is made of a suitably soft metal, i.e. a metal softer than the abutment bar, such as brass. In addition, there are no threads on the locking plug; instead, there may even be guides preventing it from turning in the hole. Alternatively, the tip thereof may have a concave shape corresponding to the shape of the abutment bar. At least, it develops, when pressed in place towards the abutment bar, a shape, i.e. a slot, corresponding to the shape of the surface of the abutment bar. This way, the locking plug does not turn towards the abutment bar when the locking screw is tightened. This non-turning character, i.e. direct pressing of the abutment bar in place, ensures positioning accuracy for the locking bar. In other words, the abutment bar positioned in place against a workpiece stays precisely stationary when locked in position.
In one embodiment of the invention, height setting plates, i.e. thin plates of a thickness of a few millimeters, corresponding to support elements in terms of shape and configuration of holes can be used between the support elements. These allow making more specific height adjustments for the support posts and abutment bars extending therefrom.
To securely make the support elements stay stationary relative to one another even in a high support post, at least two alignment holes are provided in one embodiment of the invention to the upper surface and lower surface of the support element in aligned positions. Further, the abutment structure includes a number of alignment pins to be located in the alignment holes. Thus, by positioning, for example into the alignment holes of a lower support element, alignment pins of a length greater than the depth of said holes and by pressing a second support element on top of the first one in such a way as to drive the alignment pins into the alignment holes of the lower surface in the second support element, the support elements settle accurately and with non-turning rigidity in their position in a superposed configuration.
The abutment structure according to the invention for a workpiece to be machined in a milling machine has considerable advantages as compared to prior art. The invention is simple and easy to use. Just by selecting a suitable number of different support elements and abutment bars it is possible always to form a sufficient number of the abutment surfaces or abutment points in such a way that workpieces are always firmly secured in the same place during machining. In addition, nothing prevents one from making two separate support posts with the abutment bars if for some reason one does not suffice. Further, as a modular structure, it can be easily extended just by providing new parts as needed.
The invention will be described in detail below with reference to the accompanying drawings, in which
The abutment structure according to the invention includes a body element 4, for example in
The most essential part of the invention is a support element 5 shaped as a rectangular parallelepiped as illustrated in
A hole 11 is drilled perpendicularly downward right from the middle of the upper surface 12 of the support element 5 to the middle of the lower surface 13 thereof. Further, the upper surface of the support element is provided on both sides of the hole 11 with smaller alignment holes 17 extending only to a small distance, for example for approximately 10 mm, into the support element from the upper surface thereof. Two corresponding alignment holes are also made to the lower surface of the support element. Thus, by locating, according to
The support elements 5 located in a superposed configuration are mounted to one another and to the body element 4 by a locking bar 10, i.e. a threaded bar. A connection element known per se for mounting to the mounting slot 19 of the body element 4 is disposed at the lower end thereof, and a nut 21 is threaded to the upper end of the threaded bar extending further than the uppermost support element. Thus, the support elements can be tightened into a stiff and straight support post 6.
In addition to the vertical holes described above, the support element according to the figures has four superposed support holes 8 extending in parallel from one end surface 15 of the support element to the other perpendicularly to the end surfaces. The support holes are disposed at an even distance 2a from one another,
Further, the support hole 8 can be provided with a straight abutment bar 7 extending through the support element. Extending perpendicularly into each support hole from the lateral surface 14 of the support element is a locking 9, i.e. a hole, with a locking screw 16. Thus, an abutment bar 7 can be pushed into the desired support holes 8 for a required distance and locked in position.
In addition, it is possible to use thin height setting plates 20 according to
One abutment structure according to the invention as illustrated in the figures is used as follows. When it is desirable to have workpieces to be milled always precisely in the same position for the duration of machining, a sufficiently high support post 6 is composed of support elements 5 and mounted on the milling bench 3, and the support elements are tightened against one another into a rigid assembly. After this, one or more abutment bars 7 are pushed through the support holes 8 in such a way that their one end meets the workpiece 1 that is stationary in the appropriate machining position. The abutment bars are locked in this position. A sufficient number or the abutment bars is used at different heights in such a way that the ends thereof define the precise position of a workpiece. If necessary, it is even possible to mount another support post 6 with the abutment bars onto a milling bench. It is essential that the abutment bars are used in a sufficient number at different heights as surely and precisely to define the precise position of a workpiece.
The invention has been described above by way of example with reference to the accompanying drawings; however, different embodiments of the invention are possible within the scope defined by the claims.
