EP1600269A1

EP1600269A1 - Machining center with a narrow gantry structure

Info

Publication number: EP1600269A1
Application number: EP05425366A
Authority: EP
Inventors: Alberto Ruggieri
Original assignee: Bacci Paolino Di Bacci Di Agostino
Current assignee: Bacci Paolino Di Bacci Di Agostino
Priority date: 2004-05-25
Filing date: 2005-05-25
Publication date: 2005-11-30
Also published as: ITFI20040119A1

Abstract

The machining center comprises: a base (3); a pair of guides (9A, 9B) on said base for a pair of rests (11A, 11B) for supporting work pieces (P), moving along a respective first translation axis (YA, YB) parallel to said guides; a gantry structure (5, 7) with a crossbar (7) extending above said base (3) and crosswise to said guides (9A, 9B), along which a machining head (23) moves along a second translation axis (X). To achieve a gantry of narrower dimensions, at least one of the rests is capable of a transverse movement (FA, FB) with respect to its first translation axis (YA; YB).

Description

The present invention pertains to a machining center, or machine tool, typically but not exclusively for the machining of pieces of wood. To be more precise, the invention relates to a machining center with a gantry structure and a machining head sliding along the gantry's crossbar above a base, on which there are two carriages or work piece-supporting rests that slide, each controlled in its sliding movement along a corresponding numerically-controlled working axis lying at right angles to the axis of movement of the machine head.
Machine tools or machining centers of this type are generally of considerable size, particularly in terms of their width. This is due to the fact that the span of the gantry structure must be sufficient to allow for the passage of the two work piece-supporting rests underneath it, while leaving sufficient space for the machining of the pieces even when the tools on the machining head come to be alongside the rests. As a result, the global width of the machine is greater than the sum of the maximum crosswise dimension of the work pieces that can be placed on the two rests plus the width of the upright for the gantry structure.
Machines or machining centers of this type frequently need to be transported over considerable distances, from the manufacturer's premises to the user company, by loading them in containers. Containers come in standard sizes and normal machining centers cannot fit inside them unless they are dismantled. This involves assembling the machining center for final testing, then dismantling it, loading the component parts into the container, delivering the container to the destination of the machine and then reassembling the whole machine.
The object of the present invention is to realize a gantry-type machine tool or machining center of the aforementioned kind of limited crosswise dimensions, but nonetheless capable of machining pieces of considerable size.
Essentially, the invention concerns a machining center, in particular for machining wooden components for use in furniture or the like, comprising: a base with a pair of guides for a corresponding pair of rests for supporting the work pieces, said rests being movable along a respective first translation axis parallel to said guides; a gantry structure with a crossbar running above said base and crosswise to said guides, whereon a machining head moves along a further translation axis; characterized in that at least one of the rests is also capable of a transverse movement with respect to its translation axis.
With a configuration of this kind, the rest can be moved from a working position in which it lies close to the centerline of the base and passed under the gantry structure carrying the machining head to a laterally-displaced idle position. This means that the gantry can be made with a span (i.e. the free space between the uprights) that can be narrower, for equivalent crosswise dimensions of the work pieces, than would be necessary in conventional machining centers.
Preferably, but not necessarily, both the rests can be enabled to move crosswise with respect to said guides.
In practical terms, the crosswise movement of the work piece-supporting rest(s) (or tables) with respect to their first translation axis, is parallel to the gantry crossbar and orthogonal to the translation axis of the rests.
While the movement of the rests and of the machining head along their respective translation axes is a numerically-controlled movement, the crosswise movement of the rest(s) may be a simple movement controlled by a cylinder-piston actuator, or other actuator not numerically-controlled, but rather capable of making the corresponding rest occupy two definite positions, e.g. by means of abutments and/or limit switches. Said positions will be one working position and one idle position, respectively closer and further away from the centerline of the base. It may also be, however, that this movement is also numerically-controlled.
Further advantageous characteristics of the machining center, or machine tool, according to the invention are illustrated in the attached claims and described below with reference to an example of an embodiment.
The invention will be easier to understand by means of the description below and the attached drawing, which shows a non-restrictive practical embodiment of the invention. To be more specific, the drawing shows:
Fig.1, a front view of the machining center in a first position;
Fig.2, a top view along II-II of Fig.1;
Fig.3, a top view similar to Fig.2, but in a different position; and
Fig.4, a front view in another position.
Referring initially to Figures 1 and 2, in this example of an embodiment the machining center, generically indicated by the numeral 1, comprises a base 3 and a gantry structure including a pair of uprights 5 and a crossbar 7.
On the base 3, there are two parallel guides 9A, 9B for two rests, indicated globally as 11A and 11B, arranged so as to work in a swinging cycle, i.e. so that when one rest is in the working position underneath or in the vicinity of the gantry structure 5, 7, the other is some distance from it, in an area for loading and unloading the work pieces. The pieces are fitted onto the rests in any known manner, e.g. by means of suckers, pressure pads driven by pneumatic or hydraulic actuators, or in any other means known to a person skilled in the art and not shown.
The two rests are capable of movement along a numerically-controlled horizontal traversing axis, indicated by YA and YB respectively for the two rests. Since the carriages work in a swinging cycle, one normally comes to be at a standstill in the loading and unloading position (the position of rest 11B in Fig.3), while the other moves along its respective axis Y (axis YA for rest 11A in Fig.3) controlled by a microprocessor or other programmable control unit.
According to a preferred embodiment, each of the two rests 11A, 11B has a carriage 13A, 13B sliding directly on the guides 9A, 9B. On each of the two carriages 13A, 13B a respective saddle 15A, 15B is provided, which slides on the carriage 13A, 13B in a direction FA, FB. The movement along FA and FB may be a simple movement, i.e. not controlled by a numerical control axis, but a movement obtained between two end positions induced by a cylinder-piston actuator, for instance, or by an electric motor and limit switches, or other similar arrangement. This does not rule out the possibility of this movement also being numerically controlled, however, although this would increase the cost of the machining center.
Each of the two saddles 15A, 15B can occupy a first end position coming closest to the centerline L of the base 1, and a position furthest away from said centerline. Figures 1 to 3 show the saddle 15A in the position closest to the centerline L, while the saddle 15B is in the position furthest away from said line. The purpose of this movement will be explained in more detail below.
According to a preferred embodiment, each saddle 15A, 15B carries a pair of uprights or cursors 17A, 17B, on each of which a beams 19A, 19B is fixed. The beams 19A, 19A and 19B, 19B on each rest 11A, 11B provide a surface for supporting and fixing the work pieces. The size of this surface can be adjusted by changing the distance between the uprights or cursors 17A, 17A and 17B, 17B, to adapt to the shape of the pieces being machined as the case may be. Fig. 1 also shows an example of pieces P locked onto the members 19A and 19B of the two rests.
A machining head, globally identified by the numeral 23, is slidingly installed on a guide 21, on the gantry crossbar. Said machining head is capable of movement along a numerically-controlled axis X, along the guide 21, at right angles to the axes YA, YB. The head 23 includes a saddle 25, with a vertical guide 27, along which there slides a supporting element 29 with a set of spindles 31 (in the example, four spindles fitted with a corresponding number of tools). The movement along the guide 27 is governed by a numerically-controlled axis Z. The machining head 23 may be rotational or birotational, i.e. capable of a rotational or oscillating movement of the set of spindles 31 around one or two numerically-controlled rotational axes. In the example shown a single numerically-controlled axis of oscillation is provided, indicated by the letter B.
As we can see, for instance, in Figs 1 to 3, the dimensions of the rests 11A, 11B and of the pieces P with respect to the span A of the gantry structure 5, 7 is such that the rest 11A can be brought underneath the gantry structure, so that the pieces P fixed thereon can be machined, by passing from the loading and unloading position of Fig.2 to the working position of Fig.3, after the saddle 15A has been displaced towards the centerline L of the base 1. Vice versa, the saddle 15B of the rest 11B is transferred laterally into a position such that the rest would not be able to pass under the gantry because of its limited span A.
In the arrangement of Fig. 4, on the other hand, the rest 11A is displaced laterally to an outer position (i.e. away from the centerline L), while the rest 11 B occupies a position close to the centerline of the base 1, and can shift towards the working position by passing or coming into position underneath the gantry 5, 7 to enable the head 23 to work on the pieces P.
The movement in the direction of the arrows FA and FB, thus enables one or other of the rests 11A, 11 B to be brought into a position that enables the machining of the pieces P passing under the machining head 23, requiring a gantry 5, 7 of limited crosswise dimensions, i.e. with a narrow span A and a consequently globally narrower width than would be necessary (to machine pieces of the same size) with a conventional configuration, wherein the rests are unable to move crosswise with respect to the axes YA, YB.
Clearly, some of the advantages achievable with a configuration of the kind described can also be obtained by enabling only one of the rests 11A, 11 B to move crosswise to the axes YA, YB. In fact, if we assume, for instance, that only the rest 11 B has this capacity for transverse movement, while the rest 11A always remains in a position close to the centerline L (the arrangement of Figures 1 to 3), the rest 11A can always move under the crossbar 7 of the gantry structure 5, 7, while the rest 11 B will have to perform a first movement along the axis YB, up until it comes between the loading and unloading position and the gantry 5, 7. Having reached said position, the saddle 15B can be displaced along FB towards the centerline L of the base 1, so that the rest can advance along the axis YB until it reaches the workspace for the machining head 23, underneath the crossbar 7. This solution enables the construction of one of the two rests 11A, 11 B, to be simplified, but makes it more difficult to program the machining cycles.
It shall be understood that the drawing shows just one practical embodiment of the invention, which may vary in shape and layout without departing from the concept underlying the invention. Any reference numbers in the claims are entirely for the purpose of facilitating reading thereof in relation to the description and the attached drawings, and shall not be construed to restrict the scope of the claims in any way.

Claims

Machining center, especially for machining wooden components for use in furniture or the like, comprising: a base (3); a pair of guides (9A, 9B) on said base for a pair of rests (11A, 11 B) for supporting work pieces (P), moving along a respective first translation axis (YA, YB) parallel to said guides; a gantry structure (5, 7) with a crossbar (7) running above said base (3) and crosswise to said guides (9A, 9B), on which a machining head (23) moves along a second translation axis (X); characterized in that at least one of said rests is capable of a movement (FA, FB) crosswise to said first translation axis (YA; YB).
Machining center as in claim 1, characterized in that both the rests are capable of a transverse movement with respect to said first translation axis (YA; YB).
Machining center as in claim 1 or 2, characterized in that the movement crosswise to the first translation axis of said rest(s) is parallel to the second translation axis (X) and orthogonal to the first translation axis (YA; YB).
Machining center as in one or more of the previous claims, characterized in that said first and said second translation axes (YA; YB, X) are numerically controlled working axes.
Machining center as in one or more of the previous claims, characterized in that said rest(s) can occupy two predefined positions reached by means of said crosswise movement.
Machining center as in one or more of the previous claims, characterized in that said rest(s) can move crosswise to said guides (9A, 9B) between a first position close to the centerline (L) of the base (3), wherein the rest can pass or come into position underneath the gantry structure, and a second position further away from the centerline of the base, wherein said rest cannot pass or come into position under the gantry structure, said first position being occupied during the machining of the pieces carried on the rest.
Machining center as in claims 2 and 6, characterized in that said first and second positions are occupied alternately by the two rests, one rest coming to be in the first position closer to the centerline when the other rest comes to be in the second position, and vice versa.
Machining center as in one or more of the previous claims, characterized in that each of the rests (11A, 11 B) capable of moving crosswise to the first axis of movement (YA; YB) comprises a carriage (13A, 13B) engaged on a corresponding guide (9A, 9B) extending underneath the gantry structure and sliding along said first axis of movement (YA; YB), with a saddle (15A, 15B) on said carriage capable of moving crosswise to said first axis of movement (YA; YB).
Machining center as in claim 8, characterized in that said saddle has means (17A, 17B, 19A, 19B) for supporting and fixing the work pieces (P).
Machining center as in claim 9, characterized in that said fixing means include uprights with a variable distance between centers (17A, 17B).
Machining center as in claim 10, characterized in that said uprights with a variable distance between centers each carry a beam (19A, 19B) for supporting and fixing the work pieces (P).