EP0694371A1

EP0694371A1 - Milling group for woodworking machines

Info

Publication number: EP0694371A1
Application number: EP95110956A
Authority: EP
Inventors: Gianantonio Costa
Original assignee: A COSTA SpA
Current assignee: A COSTA SpA
Priority date: 1994-07-14
Filing date: 1995-07-13
Publication date: 1996-01-31
Also published as: ITVI940108A0; ITVI940108A1; IT1267830B1

Abstract

The invention is a milling group (1a; 1b) for woodworking machines (3), comprising: a spindle (2) sustained at least at one end by at least one support (210, 220) mechanically connected with a working surface (5), said working surface (5) being removably coupled with a machine bed (51) belonging to the base (12) of said woodworking machine (3); at least a motorization unit (7) for transmitting rotation to said spindle (2); at least three milling cutters (9) coaxial to one another and coupled with said spindle (2). Said milling cutters (9) are arranged in steps and their cutting profiles (91) are aligned according to converging lines (13, 14) which substantially represent the generating lines of two coaxial truncated cones (130, 140) having common major base (15), and the woodworking process takes place indifferently on any milling cutter ideally belonging to each truncated cone.

Description

The invention concerns a milling group particularly suitable for being installed on woodworking machines, like for example spindle molding machines, matching machines and alike.
It is well known that in the woodworking sector machine tools are used, which continuously work wooden panels carrying out surface planing and edge profiling operations.
Said machine tools, which are called spindle molding machines, matching machines, etc. fundamentally consist of a base on which, by means of rollers or conveyor belts, the wooden panel to be processed advances. A plurality of milling cutters mounted on horizontal shafts positioned one after the other process the panel surfaces, while another plurality of milling cutters mounted on vertical spindles and arranged laterally carry out profiling works according to various shapes on the edges of the panel itself.
One of the problems which arise during the processing of panel edges is the friction of the tool back against the panel resulting in a bad-quality cut, which happens when deep shaping with high advancement speed of the panel must be carried out, especially if the milling cutter diameter is considerable.
Further, not all profiles can be obtained with milling cutters mounted on vertical spindles.
In order to eliminate this drawback, edge shaping works are often carried out with shaped cutters mounted on horizontal spindles which are shifted in correspondence with the edge to be profiled.
In particular, the panel is placed with one edge against a reference square fixed on the machine base, where we find also the right profiling milling cutter, while the left profiling milling cutter is placed in correspondence with the opposite edge.
Owing to the above-described solution, most problems regarding the friction of the tool back against the workpiece can be solved, but the productivity and flexibility of the machine are rather low. In fact, every time that it is necessary to change the profile to be carried out on the edge of the panel, the operator must stop the machine and replace the milling cutter with another one capable of carrying out the new profile.
In order to eliminate this drawback, two or more shaped milling cutters can be mounted on a single horizontal spindle, in such a way as to pass through slits and protrude out of the working surface on which the panel slides and in variable quantity according to the depth of the desired profile. In particular, the sliding surface of the panel and the spindle can be integrally shifted in the horizontal direction in order to vary the distance between the milling cutter and the reference square against which the panel strikes, so that it is possible to process panels having different width. Further, the spindle can be shifted vertically, with respect to the sliding plane of the panel, so that each milling cutter protrudes of the length necessary to obtain the required profile.
In the known kinds of applications, two or maximum three milling cutters are mounted on the same horizontal spindle, opposite to one another and properly spaced and having increasing diameters in the axial sense of the spindle. The milling cutters are thus arranged in steps, with their cutting profiles aligned with one another following a line which substantially represents the ideal profile of a truncated cone, divergent starting from the milling cutter which is nearest to the reference square.
However, even these solutions present some drawbacks.
First of all, the milling cutters mounted on the same spindle make it possible to work only on one side of the panel, either right or left, according to the direction of the cutting profiles. In fact, all the milling cutters mounted on the same spindle must have their cutting profile directed either to the right or to the left, since it is impossible, for example, for a milling cutter to show the right cutting profile and to be included between other two milling cutters which instead show their left cutting profile. This arrangement, in fact, would make the working with said intermediate milling cutter practically impossible, since its cutting profile would be inaccessible due to the presence of the milling cutter adjacent to it and having longer diameter.
A further drawback is represented by the fact that it is impossible to install a high number of milling cutters on the same spindle, since the excessive differences in diameter among the milling cutters would cause inacceptable differences in the cutting speed of the milling cutters themselves, above all between the extreme ones, considering that the spindle rotates with constant rpm.
The present invention aims at eliminating these drawbacks. One of the aims of the invention is the implementation of a milling group for woodworking machines, on which a single spindle can be fitted with more milling cutters in comparison with the number of milling cutters which can be installed on the known milling groups suitable for carrying out similar kinds of working.
Another aim is the implementation of a milling group in which the milling cutters mounted on the same spindle can show both right and left cutting profiles.
Another aim is to obtain a milling group in which the milling cutters can profile the workpiece both on the right and left side.
The above mentioned aims are achieved through the implementation of a milling group for woodworking machines which, according to the main claim, comprises:

a spindle sustained at least at one end by at least a support mechanically connected with a working surface, said working surface being removably connected with a machine bed belonging to the base of said woodworking machine;
at least a motorization unit for transmitting rotation to said spindle;
at least three milling cutters coaxial to one another and coupled with said spindle,

Said major base is delimited by a plane orthogonal to the spindle and is situated in the area where one or more milling cutters having the same diameter are arranged, said milling cutters having the longest diameter among all the milling cutters coupled with to said spindle.
To advantage, the spindle with which the milling group object of the present invention is fitted can be provided with a higher number of milling cutters in comparison with the number of milling cutters which can be installed on the known milling groups and this makes it possible to carry out the same kind of processing using fewer milling groups. Being provided with fewer milling groups, the machine tool is also shorter.
Still to advantage, since each spindle of each milling group can be provided with milling cutters with either right and left profile, the machine provided with the milling groups object of the invention is more flexible to use and ensures considerable time saving in comparison with the known machines suitable for carrying out similar kinds of working.
Further, each milling group can profile wooden panels indifferently on the right or left side, independently of each other.
Further, the possibility to have more milling cutters on the same spindle makes it possible to reduce the tool changes and therefore to reduce the time employed for equipping the machine.
All the above mentioned aims and advantages will be better highlighted in the description of a practical application, chosen among many, of the invention in question, illustrated in the attached tables:

fig. 1 shows a schematic side view of a woodworking machine, on which a plurality of milling groups object of the invention are mounted;
fig. 2 shows a longitudinal section of the milling group object of the invention;
fig. 3 shows the section of the machine of fig. 1 in detail, carried out according to the drawing plane and in correspondence with a milling group;
figures 4, 6, 8 and 10 show sections of the machine of figure 1 according to the A-A plane, obtained in correspondence with a first milling group object of the invention, where it is possible to observe the working of the panels in correspondence with one edge;
figure 5, 7, 9 and 11 show sections of the machine of figure 1 according to the B-B plane, obtained in correspondence with a second milling group object of the invention, successive to the first group, where it is possible to observe the working of the same panels shown in figures 4, 6, 8 and 10 in correspondence with other edges.

A section of the milling group object of the invention, referred to as a whole by 1, is shown in figure 2, where it can be observed that it comprises a spindle 2 sustained by supports 210 and 220 mechanically coupled with a working surface 5 of a woodworking machine, referred to as a whole by 3, the lateral view of which is shown in fig. 1. The spindle 2 is provided at one end with a pulley 6 which is set in rotation by a motorization group, referred to as a whole by 7 and visible in fig. 3, by means of a driving belt 71.
In particular, a series of milling cutters 9 is mounted on said spindle 2, each of said milling cutters showing a different cutting profile 91.
Each one of said milling cutters 9 shown in detail in figure 3 protrudes out of the working surface 5 through proper slits 92, so as to contact the panel 10 to be processed. The panel 10 advances on the working surface 5 and on the machine bed 51, with which said working surface 5 is coupled, and is pushed by advancing rollers or belts, which are not shown in the pictures. Moreover, as shown in figures 2 and 3, in order to carry out the working on the panel edge the machine is provided with a square 11 which is fixed to the machine bed 51, in turn fixed to the base 12 of the machine itself and against which the other edge of the panel strikes, as will be better explained below.
As shown in fig. 2, these milling cutters 9 are arranged in steps and their cutting profiles 91 are aligned with one another following the lines 13 and 14, which substantially represent the generating lines of two coaxial truncated cones 130 and 140 having common major base 15, said major base being practically delimited in the area where one or more milling cutters having the same diamter are placed, said milling cutters having the longest diameter among all the milling cutters coupled with said spindle. In the case represented in fig. 2 said major base 15 is delimited in an intermediate position between two milling cutters having the same diameter.
In a different application said major base 15 can be delimited in correspondence with a single milling cutter having longer diameter than the other milling cutters, said milling cutter being also provided, if necessary, with either right and left cutting profile.
It can also be observed that on the same spindle 2 the milling cutters 9 are mounted with cutting profiles directed both rightwards and leftwards, which means that with the milling cutters mounted on the same spindle it is possible to work a panel on both edges.
As to the working surface 5, this is coupled in a seat obtained on the machine bed 51, with which it forms a single supporting surface for the advancement of the panel to be processed.
The milling group 1 is provided with a frame 110 integral with the working surface 5, since, as shown in fig. 3, they are connected with each other by the sliding union pin 17. Further, the frame 110 of the milling group is supported by a moving saddle 18, to which it is connected by means of a screw-nut screw coupling 21, while said moving saddle 18 is in turn coupled with a fixed countersaddle 19 belonging to the base 12 of the machine. The working surface 5 and the milling group 1 can slide integrally with each other and transversally to the machine, orthogonally to the plane of figure 3, through the movement of the mobile saddle 18 on the fixed saddle 19. Further, the milling group 1 can be vertically shifted according to any of the directions indicated by the arrow 20 through the screw-nut screw coupling, referred to as a whole by 21.
Therefore, with reference to figures 2 and 3, the working surface 5 and the milling group 1 can be shifted integrally with each other following any of the directions of the arrow 22 and relatively with respect to the square 11, according to the width of the panel to be processed. Further, only the milling group 1 can be moved according to any sense in the vertical direction 20, so as to adjust the protrusion of any milling cutter with respect to the working surface 5 and to obtain a profile with varying depth.
In order to better describe and understand the operations which the milling group object of the invention can carry out, we make reference to two milling groups installed on the same machine shown in figure 1, which are arranged one after the other. More particularly, with respect to the advancing direction 31 of the panel to be processed on the machine bed 51, two successive milling groups are taken in consideration, and precisely a first milling group indicated by 1a and represented in section in figures 4, 6, 8 and 10 and a successive second milling group 1b also represented in section in the figures 5, 7, 9 and 11, which is equal to the first group, apart from the fact that the milling cutter profiles are different.
As shown in figure 4, the right edge 101 of the panel 10 is placed against the square 11, so as to process said edge 101 with the milling cutter 9a having the cutting profile 91a and belonging to the first milling group 1a. Afterwards, as shown in fig. 5, the panel advances in the direction 31 keeping the right edge 101 against the square 11 and the cutting profile 91b of the milling cutter 9b of the second milling group 1b shapes the left edge 102 of the panel 10 itself.
Obviously, on said edge 102 of the panel 10 another profile could be carried out according to another right cutting profile of the other milling cutters, by properly moving the milling group 1b with respect to the square 11 according to either direction of the arrow 22.
Fig. 6 shows the processing of a panel 30 which is worked in correspondence with its right edge 301 by means of the cutting profile 91c of the milling cutter 9c belonging to the milling group 1a and then in correspondence with its left edge 302 by means of the cutting profile 91d of the milling cutter 9d which, as shown in fig. 7, belongs to the milling group 1b.
A further panel 40, as shown in fig. 8, is first worked in correspondence with its left edge 402 by means of the cutting profile 91e of the milling cutter 9e belonging to the milling group 1a, keeping it against the square 11 itself and subsequently, as shown in fig. 9, it is worked in correspondence with its right edge 401 by means of the cutting profile 91f of the milling cutter 9f belonging to the milling group 1b.
A further example is shown in fig 10, where it can be observed that a panel 50 is worked first in correspondence with its left edge 501 by means of the cutting profile 91g of the milling cutter 9g belonging to the milling group 1a and then, as shown in fig. 11, it is worked in correspondence with tis right edge 502 by means of the cutting profile 91h of the milling cutter 9h belonging to the milling group 1b.
It is obvious that the above-described examples are only some of the possible choices for the kind of working to carry out on panel edges, since by moving horizontally and opportunely both the milling groups 1a and 1b together with the relevant working surfaces 5 with respect to the fixed square 11, it is possible to obtain further profile combinations on the panel sides. Moreover, by moving only the milling groups 1a and 1b vertically it is possible to vary the depth of said profiles.
The above description shows that the milling group object of the invention achieves all the set goals.
As first thing, it achieves the implementation of a milling group in which a higher number of milling cutters can be installed on a single spindle, in comparison with the number of milling cutters which can be installed on the known milling groups suitable for carrying out similar kinds of working. In fact, according to the examples and the pictures the spindle of each milling group is provided with six milling cutters, but this is only an example chosen among many, since the spindle can be as long as desired and any number of milling cutters can be mounted on it, each milling cutter having a different profile.
It is also possible to reduce the time necessary for equipping the machine, since several milling cutters different from one another can be fitted on the same spindle.
The achievement of the fixed goals also makes it possible to get all the advantages connected with these, which mainly consist in higher flexibility of the machine, allowing rapid change of the profiles which can be obtained on the panels with no need to change the tools.
Further, the greater variety of profiles which can be obtained with the milling cutters mounted on the spindle of each milling group ensures, as already explained, the reduction of the number of milling groups mounted on the machine, which, with the same number of profiles to carry out, is shorter than other machines fitted with milling groups of the known kinds.
Obviously, the milling cutters with which each milling group is fitted can have any profile and diameter and can be installed in any number.
Upon implementation any change can be made in order to make the milling group object of the invention easier to build or more economical and any of these possible variants is to be regarded as completely protected by the invention in question.

Claims

Milling group (1a; 1b) for woodworking machines (3), comprising:
- a spindle (2) sustained at least at one end by at a least support (210, 220) mechanically connected with a working surface (5), said working surface (5) being removably coupled with a machine bed (51) belonging to the base (12) of said woodworking machine (3);

- at least a motorization unit (7) for transmitting rotation to said spindle (2);

- at least three milling cutters (9) coaxial to one another and coupled with said spindle (2),
characterized in that said milling cutters (9) are arranged in steps and their cutting profiles (91) are aligned according to converging lines (13, 14) which substantially represent the generating lines of two coaxial truncated cones (130,140) having common major base (15), and in that woodworking can take place indifferently on any milling cutter ideally belonging to each truncated cone.
Milling group (1a; 1b) according to claim 1), characterized in that said major base (15) common to both said truncated cones (130, 140) is delimited by a plane orthogonal to the spindle (2) and is situated in the area where one or more milling cutters (9) are positioned, said milling cutters having the same diameter (9c; 9e; 9d) and said diameter being the longest among all the diameters of the milling cutters coupled with said spindle.
Milling group (1a; 1b) according to claim 1) or 2), characterized in that all the cutting profiles (91) of said milling cutters (9) aligned on the same line (13, 14) defining the generating line of the relevant truncated cone (130, 140) are directed in the converging sense of said truncated cone.
Milling group (1a; 1b) according to the previous claims, characterized in that it is provided with a frame (110) mechanically coupled with said working surface (5) by means of a sliding union pin (17), said frame (110) being in turn connected with a mobile saddle (18) through shifting means (21), said mobile saddle being coupled with a fixed countersaddle (19) belonging to the base (12) of said woodworking machine (3).
Milling group (1a; 1b) according to claim 4), characterized in that said shifting means consist of a screw-nut screw coupling (21) which accomplishes the vertical shifting of said milling group (1a; 1b) with respect to said working surface (5).
Milling group (1a; 1b) according to claim 1, characterized in that said working surface (5) is slidingly coupled with said machine table (51) of said woodworking machine (3) and can be moved on said machine table (51) transversally to the longitudinal axis of said woodworking machine (3).