LU82096A1 - IMPROVEMENTS ON MACHINE TOOLS OF THE MACHINING CENTER TYPE - Google Patents

Description

The present invention relates to improvements made to machine tools of the so-called type: machining center with a view in particular to increasing productivity.

Among the different types of machine tools operating by chip removal, one can oppose the machines in which the workpiece is driven relative to a stationary tool, machines qualified as a machining center in which the tool is mobile and in particular rotary, relative to a fixed part, during machining.

The advantages, disadvantages and limitations of each type. pe machines are well known. It will be recalled only that, the first type of machine tool is limited to the production of parts of revolution but allows numerous dimensional variations using a single tool.

ÎThe machines of the machining center type allow the machining of complex parts, usually comprising flat surfaces, by boring, milling, etc. The use of digital controls and microprocessor equipment makes it possible to modify, if desired, without difficulty for each successive part the work carried out. Each unit operation in principle requires a tool | appropriate and such machines are equipped accordingly with a tool magazine and transfer members to quickly replace the tool used at the end of each sequence of use.

Such machining centers are equipped with a single generally horizontal spindle, movable along three perpendicular axes and usually comprising aurona- transfer means! workpiece ticks that are normally arranged | - it / on a rotary table in order to be able to machine it under different plans.

The major drawback of this type of equipment is the fact that the single tool makes it possible to carry out only one operation on the part and that the elementary operations must necessarily take place sequentially.

For some operations, such as drilling a r hole. passing through a gearbox for example, a particular difficulty results from the overhang of the tool mounted on the single spindle, making the accuracy of the work done> random and limiting the forces applicable to the tool.

^ Rectilinear transfer machines are also known in which the parts are mounted on plates forming links of an endless chain and are thus moved from one work station to the next. At one or more workstations, it is possible to provide for simultaneous machining of the part arriving at this workstation using several autonomous machines. Such machines are intended for sequentially repetitive operations, in particular in automobile assembly lines. They constitute a particular solution for the specific cases of this sector and represent an expensive investment; they of course occupy large areas and are only applicable to mass production.

* The invention aims to avoid the cited drawbacks of existing equipment and to increase the production rate of a machining center without additional operator intervention.

According to the invention, a machining center comprising a table supporting the workpiece or workpieces remaining stationary during machining, a tool magazine and a tool J- / t / ï j ♦ switching device is characterized by the fact that it is equipped with at least! two rotary tool holders operating simultaneously.

Said tool holders can receive identical or different tools or, as will be seen below, can receive for the first a tool and for the second a corresponding receiving scope.

: The use of at least two tool holders, while preserving the advantages inherent in a machining center, namely! I the great flexibility of operation makes it possible to increase the productivity of the installation.

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Indeed, the operating principle of single-spindle machine centers of the prior art assumed a displacement of the part, generally by rotation on the support table, at each operating sequence, accompanied or not of the modified positioning of the tool holder, while according to; * the inventive concept described, the part is machined simultaneously '1 i under several angles of attack, using a single machining center equipment and under the supervision of a single opera-; tor.

S In addition, this new approach to design and | the use of a machining center opens up new perspectives for the use of applications.

Advantageously, the tools are designed to work ► by performing the same operation, and this symmetrically with respect to a reference axis.

In this way, while having the advantage of reducing the machining time, it is also possible to simplify the control equipment, each tool receiving identical working instructions. When the space permits, it thus becomes possible to machine 4; imult.'mément two pieces using a single machining center.

A significant simplification can thus occur at the level of the tool storage equipment, since a single magazine, of adequate size and shape, and a single tool permutation equipment or several tool permutation equipment can used to power the various tool holders.

Two tool holders can, when they are arranged in alignment with one another, make it possible to mount a tool on a tool holder and another tool or a telescope supported by the other tool holder.

The two tools are then secured by interlocking JL'un into each other or the tool and the bezel can also be secured by interlocking.

This solution is particularly advantageous in the case of making a hole passing through a multi-partitioned room, such as a gearbox, because it makes it possible to carry out a work known as "in bar" while avoiding the problems linked to the pins in poï * te - false. Indeed, the tools of each tool holder or the tool of a tool holder and the telescope. corresponding to the poor tool holder, after being secured by interlocking, form a rigid bar supported at both ends by ballast bearings of the corresponding tool holders.

The invention will be described in more detail with reference to the accompanying drawings which are intended solely to illustrate the invention and do not have any limiting character. On reading this description, other advantages and additional characteristics of the invention will appear to those skilled in the art of | art.

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In the drawings: - Figure 1 shows a plan view of a machining center according to the invention; - Figure 2 shows a side view of a machining center according to the invention; - Figure 3 shows a side view of a machining center according to the invention illustrating the work "bar" by nesting of the elements carried by two tool holders; - Figure 4 is a detailed view of a possibility of nesting of the elements of Figure 3, corresponding to the nesting of two tools between them; - Figure 5 is a detail view of another alternative nesting possibility, elements of Figure 3 corresponding to the nesting of a tool on a telescope; - Figures 6 to 9 illustrate the working possibilities of one or more parts, using a machining center device according to the invention.

Identical references have been used in the different figures for identical elements or for similar elements exercising the same functions in the different views.

In FIGS. 1 and 2, a machining center mounted on a circular base 1 porfceen at its center a rotary table 2, on which the workpiece is fed or, if necessary, several workpieces are fed.

Unlike the embodiments of the state of the art which comprises a single spindle supplied from a tool magazine by a tool exchanger, the characteristic of the invention is the fact that the center of machining comprises several tool holders 11, 12,13,14 ... which are / y 7 preferably supplied from a single magazine 3, by one or more tool exchangers 4,4 '.

The different tool holders can be equipped with identical or different tools, for example tools 21, 22, 23 and 24 shown in FIG. 1 and / or in FIG. 2.

In the usual way, these machining units are displaceable in the same way as the single spindle of the machining centers of the state of the art within the limit of course of the mutual space requirement of the different individual tool holder units . The movements planned for the different individual units in the three planes are represented by the arrows.

The movement of movement of the table 2, in addition to the pivoting movement on its center is also indicated by arrows.

Hatched arrows indicate the movements of the tool exchangers.

The table can in particular carry out a lateral clearance movement as indicated while the different individual machining units are displaceable on the base 1.

In this most general embodiment of the invention, the relative arrangement of the individual tool holders is free but their arrangement is coordinated and can be controlled by a microprocessor according to the machining operations to be carried out.

The principle on which the invention is based has its most marked favorable effects in the case of the particular embodiment shown in Figures 3, 4 and 5.

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18

In this case, the tool holders of two machining units (respectively 11, 21 and 13,23) of a machining center are aligned with respect to each other in a suitable arrangement for the operation to be performed on part 50.

In Figure 4, there is shown how a tool 21 by a pin 61 is supported in a housing 62 formed in the opposite tool 23. Each of the tools carries elements of size 63,64 adapted to the work to be performed on the room 50.

In the variant shown in FIG. 5, the tool 21 cooperates with a bezel 23 serving to support the tool 21.

The two variant embodiments shown in FIGS. 4 and ^ 5 make it possible to execute machining operations such as those represented in FIG. 3 with precision, avoiding the drawbacks of the overhang that would have to be suffered if the tool 21 was not supported during machining, either as shown in Figure 4, or as shown in Figure 5.

Figures 6 and 7 illustrate how two parts A and A 'which are for example covers can be' machined simultaneously by performing the large diameter drilling 1 and 1 'and the small diameter drilling 2 and 2', by a rotational symmetry around the y axis (Figure 6) and the x axis (Figure 7).

FIG. 8 illustrates the way in which drillings can be carried out on a box, both passing boreholes of constant diameter as well as aligned boreholes of different diameter.

I * 9

In the case of Figure 9, the successive operations achievable on two boxes are shown schematically by the numbers 1 to 4 and 11 to 4 'according to the principles of the invention.

Although particularly preferred embodiments of the invention have been described, it should be understood that many variants and modifications can be made while remaining within the scope of the invention.

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Claims (7)

1. Machining center comprising a support table carrying the workpiece (s) which remain fixed during machining, a tool magazine and a tool permutation device, characterized in that it is equipped with at least two rotary cutter holders operating simultaneously. 2. Machining center according to claim 1 characterized in that said tool holders receive identical or different tools. 3. Machining center according to claim 1 characterized in that a first tool holder receives a tool and that a second tool holder is provided with a corresponding receiving telescope. 4. Machining center according to claim 1 or 2 characterized in that the tools are designed to work by performing the same operation, and this symmetrically with respect to a reference axis. 5. Machining center according to any one of Claims 1 to 4, characterized in that a single magazine and a single tool permutation equipment or several tool permutation equipment are used to supply the various tool holders. 6. Machining center according to claim 1 or 2 characterized in that two tool holders are arranged in ¥ alignment with respect to each other and that a tool is mounted on each tool holder, These tools being more solidarized t by fitting one into the other. 7. Machining center according to claim 1 or 2 characterized in that two tool holders are arranged in alignment with one another and that a tool is mounted; I on a tool holder and a bezel on the other tool holder,: '2— the tool and the bezel being further secured by fitting the tool into the bezel, / ^ ^ u- "% *