Abstract:
The present invention describes a head for machine tool on which an electro-spindle is mounted and in particular it describes a tilting head for machine tool on which an electro-spindle is mounted. In one embodiment the invention comprises a tilting head for machine tool comprising: one support element coupled to said tilting head; one electro-spindle; one cradle suitably shaped to incorporate and hold said electro-spindle pivoted on said support element so that it can turn around an axis perpendicular to the axis of said tilting head; said electro-spindle being set up to have mechanic, electric, pneumatic and hydraulic connections with said cradle; wherein said connections of said electro-spindle are of the releasable type so that said electro-spindle is interchangeable and can be rapidly coupled to and uncoupled from said cradle.

Description:
FIELD OF THE INVENTION 
     The present invention refers to a head for a machine tool on which an electro-spindle is mounted, and in particular it refers to a tilting head for machine tool on which an electro-spindle is mounted. 
     BACKGROUND OF THE INVENTION 
     The head of a machine tool is the part where the spindle or the electro-spindle is housed, and that is a spindle containing the tool drive motor. In particular, a tilting head is a complex machine having one or two movement axes in addition to the movement axes already present in machine tools, which can, for example, be two or more. 
     A two-axis tilting head has a first element that rotates around a first axis convergent to the axis of the head and a second element, connected to the first element, that rotates around a second axis transversal in relation to the first axis. The electro-spindle, to which the working tool will be applied, is connected to the second element. The means of fastening to the machine tool (thrust rings) are associated to the head, which can permit the movements mentioned above, the motor members and eventual reduction gears and gears for transferring the motion. Also present are the means for the electric, hydraulic and pneumatic connections necessary for operating and controlling the tilting head. 
     Machine tools are well known, in particular those of large size, in which the head can be replaced to be able to connect another, automatically or semi-automatically so as to carry out working operations with different speeds and power. 
     In view of the state of the technique described, object of the present invention is to provide a versatile head for machine tool which also enables different types of working operations to be carried out. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, said object is reached by means of a tilting head for machine tool comprising: a support element coupled to said tilting head; an electro-spindle; a cradle with a suitable shape for incorporating and holding said electro-spindle pivoted on said support element so that it revolves around an axis which is perpendicular to the axis of said tilting head; said electro-spindle being set up to have mechanic, electric and pneumatic connections with said cradle; wherein said connections of said electro-spindle are of the releasable type so that said electro-spindle is interchangeable and can be rapidly coupled to and uncoupled from said cradle. 
     Said object is also reached by means of a system of coupling and uncoupling an electro-spindle from a cradle fixed on a machine tool, shaped so as to incorporate and hold said electro-spindle; said electro-spindle being set up to have mechanic, electric, pneumatic and hydraulic connections with said cradle; wherein said connections of said electro-spindle are of the releasable type so that said electro-spindle is interchangeable and can be rapidly coupled to and uncoupled from said cradle. 
     Said object is also reached by means of a machine tool having a head in accordance with the present invention. 
     Thanks to the present invention, it is possible to make a head in which only the electro-spindle, an element of reduced size, light and low cost, can be rapidly changed. Thanks also to the fact of the lower cost of an electro-spindle compared to a head, numerous electro-spindles with different configurations and/or power can be kept available so as to permit working both with large tools at low speed for roughing and with small tools at high speed for finishing. 
     Thanks to the present invention, in a machine tool with tilting head the interchangeability of the spindle gives greater versatility and is carried out in a simpler way and at lower cost than that of the change of the whole head. This goes also for a machine tool without tilting head. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The characteristics and advantages of the present invention will appear evident from the following detailed description of several embodiments thereof, illustrated as non-limiting example in the enclosed drawings, in which: 
     FIG. 1 represents an embodiment of the head of a machine tool in accordance with the present invention with internal tool coupling device; 
     FIG. 2 represents the front view of an electro-spindle; 
     FIG. 3 represents a section along the line A-B of FIG. 2, of an electro-spindle connected to its support cradle; 
     FIG. 4 represents a section along the line A-B of FIG. 2, of an electro-spindle partially extracted from its support cradle; 
     FIG. 5 shows the rear surface of the electro-spindle of FIG. 4 with the relative connectors; 
     FIG. 6 shows the internal bottom surface of the cradle of FIG. 4 with the relative connectors; 
     FIG. 7 represents a section of an electro-spindle connected to its support cradle; 
     FIG. 8 represents a section of an electro-spindle partially extracted from its support cradle; 
     FIG. 9 shows the rear surface of the electro-spindle of FIG. 8 with the relative connectors; and 
     FIG. 10 shows the internal bottom surface of the cradle of FIG. 8 with the relative connectors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to a preferred embodiment, a two-axis tilting head  10  is represented in FIG.  1 . 
     The tilting head  10  comprises a first thrust ring  11 , so that the head  10  can be connected to a 3 axis machine tool (not shown) for example. A body  12  connected to the thrust ring  11  (machine side), is set up for electric, hydraulic and pneumatic connections between the head  10  and the machine tool. The base of a U-shaped support  13 , is connected to the thrust ring  11  (head side). The support  13  is thus free to rotate around a first axis (axis of the head) corresponding to the axis of the thrust ring  11 . 
     A cradle  14 , shaped so as to incorporate and hold an electro-spindle  15 , is pivoted  14  at the ends of the support U  13 , along a second axis perpendicular to the axis of the thrust ring  11  (first axis). 
     The cradle  14  is activated by a motor, by an eventual reduction gear, by eventual rotary motion transmission gears  16  on a third axis parallel to that of the motor placed on support  13 . A second thrust ring (not shown) is used as interconnecting means between the cradle  14  and the support  13 . 
     FIG. 2 represents the front view of an electro-spindle  15  with the coupling means  17  of the tool, where the layout of the hydraulic coupling/uncoupling devices  20  between the electro-spindle  15  and the cradle  14 , and of the alignment pin  21  can be noted . Preferably, four devices  20  and one pin  21  are present. 
     FIG. 3 represents a transversal section along the line A-B of FIG. 2, of an electro-spindle  15  connected to its support cradle  14 , and FIG. 4 of an electro-spindle  15  partially extracted from its support cradle  14 . 
     The electro-spindle  15 , at one of its extremities, that where the tool will be applied, is provided with a flange  26  which will come up against the extremity of the cradle  14 . The tangs  25  are placed on the flange  26 , blocked in their seats on the cradle  14 , by the hydraulic coupling/uncoupling devices  20  of the electro-spindle  15 . Flange  26  is also provided with alignment pin  21  which can be positioned in the respective seat on cradle  14 , to ease the alignment between the electro-spindle  15  and the cradle  14  during insertion and to keep it when it has been blocked. 
     The electro-spindle  15 , at the rear of flange  26 , has the body, for a preset part, of conical shape  30  (ASA type), suitable for adhering to a corresponding conical part  31  placed on the cradle  14 , to support the centering between the electro-spindle  15  and the cradle  14 . It is preferable if two more elements are present, made to touch each other to improve the centering of the electro-spindle  15  in the cradle  14 , an element  32  is placed on the electro-spindle  15  and an element  33  is placed on the internal side surface of the cradle  14 , placed, preferably, at about mid-length of the electro-spindle  15 . 
     On the rear surface of the electro-spindle  15  are visible the electric connectors  22   a  and the hydropneumatic connectors  23   a  suitable for coming into contact and coupling with the respective electric connectors  22   b  and hydropneumatic connectors  23   b  placed on the internal surface of the bottom of the cradle  14 . 
     The hydropneumatic interconnection drilling between the connectors  23   b  and the external environment, which are permanently connected to corresponding drillings of a rotating distributor (not shown) keyed on the axis perpendicular to the axis of the head, are also partially visible. 
     Preferably, the cradle  14  is subdivided into two parts that are separable by means of suitable fixing screws. A first part  14   a  corresponds to the rear part of the cradle  14 , where the various connections are installed, and a second part  14   b  corresponds to the remaining part of the cradle  14 . In this manner, it is possible to extract the first part  14   a  for greater visibility and easier maintenance of the connections  22  and  23 . 
     FIG. 5 shows the rear surface of the electro-spindle  15  of FIG. 4, that is the flange  26  with the relative electric connectors  22   a  and the hydropneumatic connectors  23   a.    
     FIG. 6 shows the internal bottom surface of the cradle of FIG. 4, which comes up against the flange  26 , with the relative connectors  22   b  and  23   b  positioned so that they connect to the connectors  22   a  and  23   a.    
     The hydropneumatic connections  23  comprise the hydraulic connections (water, oil) and the pneumatic connections (compressed air) necessary for the operation of the electro-spindle  15 , namely cooling, tool change, tool cooling, pneumatic barrier and tool cleaning. Quick coupling connectors are used, in which the coupling and the separation are carried out automatically without leakages. The connectors are for example of the CyFit type made by the company CyTech. 
     The coupling/uncoupling hydraulic devices  20  of the electro-spindle  15 , are for example of the pneumatic control type, of the CyDim type made by the company CyTech. 
     Once the tang  25  has been blocked through the application of compressed air, to a first point of air input, the devices  20  can keep the blocking force without the support of pressure. To release it, the support of compressed air to a second air input point is again necessary. 
     The quick coupling electric connectors  22 , type MIL, are of two types, a first type is for feeding the motor of the electro-spindle, and a second type is for the control signals, such as those for change and presence of tool, vectorial or revolution indicator control, thermal probes, overload cutouts etc. 
     In the example of the embodiment of the invention described up to this point, the electro-spindle  15  is set up for the connection in a cradle  14  applied to a two-axis tilting head  10 , but it can also be applied to a tilting head with only one axis, (for example only the second axis perpendicular to the axis of the head). Or, the electro-spindle  15  can also be applied directly to a machine tool: the cradle  14  can be applied to the machine tool, by means of special fixing means, leaving or not the possibility of the possible subdivision of the cradle  14  into the two parts  14   a  and  14   b , or be integral part of the machine tool itself. 
     An alternative embodiment of the electro-spindle  15  and of the cradle  14 , in accordance with the present invention, is shown in section, in FIG. 7 with the electro-spindle  15  blocked and in FIG. 8 with the electro-spindle  15  partially extracted from its support cradle  14 . 
     The fastening between the rear part  14   b  and the front part  14   a  of the cradle  14  comes about by means of screws  50 . The fastening between the electro-spindle  15  and the cradle  14  comes about by means of screws  51 . At least one alignment pin  21  is always present on the flange  26  of the electro-spindle  15  and at least one respective seat on the cradle  14 . 
     On the rear surface of the electro-spindle  15  the power and signal electric connectors  22   a , are visible, with the respective electric connectors  22   b  on the internal surface of the cradle  14 , and the connector  23   a  with respective  23   b  for the connection of the cradle with the pneumatic device  14   b  for coupling the tool. 
     In addition, the drillings  53  of hydropneumatic interconnection between the electro-spindle  15  and the external environment are also partially visible, for the services of automatic tool change, cone cleaning, pneumatic labyrinth, cooling etc. 
     FIG. 9 shows the rear surface of the electro-spindle  15  of FIG. 8 with the relative power and signal electric connectors  22   a.    
     FIG. 10 shows the internal bottom surface of the cradle  14  of FIG. 8 with the relative electric connectors  22   b  positioned so that they can connect to the electric connectors  22   a.    
     In accordance with the present invention, and in particular to the embodiment shown in FIGS. 3 and 4, in the case of replacement of the electro-spindle  15 , in automatic mode, the machine tool controlled by its control member moves the arm on which the tilting head is mounted towards the electro-spindle store zone, it positions itself correctly on a picking element suitable for holding and storing the electro-spindle, releases the hydraulic coupling/uncoupling hydraulic devices  20  between the electro-spindle  15  and the support  13 , and through suitable movement (traction) between the picking element and the tilting head the electric and hydropneumatic connectors are released (automatically). The electro-spindle at this point is completely released and put away, the arm of the machine tool can thus move and automatically and autonomously couple another electro-spindle. 
     Should the hydraulic coupling/uncoupling hydraulic devices  20  not be present between the electro-spindle  15  and the support  13 , but the electro-spindle is fixed by means of screws to the cradle  14 , an operator can release it from its seat by unscrewing the screws, extract it automatically, for the electric connections, and automatically insert another one and fix it with the screws to the cradle  14 . 
     It should be understood that a wide range of changes and modifications can be made to the preferred embodiments described herein without departing from the scope and spirit of the invention which are defined in the following appended claims.