Abstract:
The invention concerns a partitioning device (D) between the machining station and a machine-tool driving station (M) of the type driving at least two tool-holder rams ( 100, 100 ′). Said device is characterized in that it consists, at least between the two rams ( 100, 100 ′), of a flexible curtain ( 500 ) called a central curtain whereof the two ends ( 510  and  520 ) are integral with a first ram ( 100 ) and which is linked to the second ram ( 100 ′) so that the relative movement of one ram ( 100  and/or  100 ′) with respect to the other ( 100 ′ and/or  100 ) along a first axis of movement (X), stretches more or less a length of curtain ( 500 ) between the two rams ( 100  and  100 ′). The invention is useful for separating the machining station from a station driving a double-spindle machine-tool.

Description:
[0001]    The present invention relates to the field of high-speed machine tools of the type that employ two tool holder rams, and especially adaptations that permit separation of the machining station of this type of machine tool from its driving station.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    The design of high-speed machine tools of the type that move two tool holder rams (so-called double spindles) has required the development of new means of separation between the machining station proper and the driving station. The different existing cowlings were specially adapted to follow a single moving device, not several.  
           [0003]    Moreover, since the technique of linear drives has become generalized, separation between the machining station and the driving station must be particularly effective at the risk of seeing the chips produced by machining attracted by the magnetic fields and contaminating the drives and guides of the machine tool.  
           [0004]    Machine tool designers have also conducted research to adapt the conventional means of separation to a machine tool of the double spindle type.  
           [0005]    One of the design criteria for the cowlings resides in the maximum approach distance between the two rams. The closer the rams are capable of approaching, the more productive the machine tool will be, owing to the use of a common machining zone and its capacity to allow the two rams and the tools that they carry to function at the same time without interfering with each other.  
           [0006]    Naturally, a technological solution utilizing the characteristics of bellows exists, but it cannot meet all the requirements and cannot be adapted to all machining applications.  
           [0007]    In addition, the movements caused by kinematic structures that use linear motors have a speed such that bellows cannot open and close correctly. Moreover, the folds created by the bellows become storage zones for chips, which prevent proper functioning of these technological solutions.  
         DESCRIPTION OF THE INVENTION  
         [0008]    With this state of affairs as a point of departure, the applicant conducted research, whose purpose was to design a technological solution to ensure separation between the machining station and the driving station of the high-speed machine tool of the type that drives at least two rams.  
           [0009]    This research led to a particularly original separation device that optimally meets the requirements of approach of the two rams, while providing perfect sealing.  
           [0010]    The separation device between the machining station and the driving station of a machine tool of the type that drives at least two tool holder rams advantageously consists, at least between the two rams, of a flexible curtain, called a central curtain, whose two ends are integral with a first ram and connected to the second one, so that the relative movement of one ram relative to the other extends along a first axis of movement by about one length of the curtain between the two rams.  
           [0011]    This characteristic is particularly advantageous, in that it offers vertical separation between the machining station and the driving station of the machine tool, capable of being used for any machining application.  
           [0012]    Moreover, its retraction permits this separation device to meet the requirement of minimum space between the two rams by means of a panel that deforms when the two rams approach. Continuous presentation of a vertical protection wall not only guarantees good separation of the two machining and driving stations of the machine tool, but also facilitates guiding of this wall, as well as sealing of this guide relative to the machine tool frame. Apart from technological solutions of the bellows type, it is particularly difficult to guarantee perfect sealing at the level of the space defined between the two rams.  
           [0013]    The fundamental concepts of the invention just described above in their most elementary form, other details and characteristics, will follow more clearly on reading the following description with reference to the appended drawings, given as non-limiting examples of a variant of the separation device according to the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a rear perspective view of a variant of the device of the invention in the closed position, where the two rams are close to each other.  
         [0015]    [0015]FIG. 2 is a rear perspective view of the device of FIG. 1 in the open position, where the two rams are separated from each other.  
         [0016]    [0016]FIG. 3 is a front perspective view of a machine tool, to which the device of the invention could be adapted.  
         [0017]    [0017]FIG. 3 b  is a front view of the machine tool of FIG. 3 a.    
         [0018]    [0018]FIG. 4 a  is a schematic top view, illustrating the functioning principle of the separation device of the invention, connecting the two rams in the adjacent position.  
         [0019]    [0019]FIG. 4 b  is a schematic top view, illustrating the functioning principle of the separation device of the invention, connecting the two rams in the separated position. 
     
    
     DESCRIPTION OF PREFERRED VARIANTS  
       [0020]    According to one preferred, non-limiting variant and to facilitate description of the device of the invention, the machine tool, on which the device of the invention will be considered to be installed, will be the one shown in FIGS. 3 a  and  3   b . As shown in the drawings of FIGS. 3 a  and  3   b , the machine tool denoted M in its entirety ensures movement of two rams  100  and  100 ′ by means of a linear motor along the three illustrated axes X, Y and Z.  
         [0021]    The objective of the device of the invention is to optimally ensure separation of the driving station situated to the rear from the machining station situated to the front of rams  100  and  100 ″ which ensure driving of the machine tool in conventional fashion (not shown).  
         [0022]    According to the depicted variant, said rams  100  and  100 ′ are each mounted in a headstock  200  and  200 ′, containing the means necessary to drive and guide rams  100  and  100 ′ along the Z-axis. These headstocks  200  and  200 ′ are each connected to a semi-table  300  and  300 ′, which contains means of driving and guiding of said headstocks along the Y-axis. Finally, the two semi-tables  300  and  300 ′ are connected to the same vertical frame  400 , which contains the means necessary for driving and guiding said two semi-tables  300  and  300 ′ along the X-axis.  
         [0023]    Another objective of the device of the invention is to permit maximum approach of the two rams  100  and  100 ′ along the X-axis.  
         [0024]    According to the variant illustrated by the drawings in FIGS. 4 a  and  4   b , the separation device of the invention, denoted D in its entirety, is characterized by the fact that it consists, at least between the two rams  100  and  100 ′, of a flexible curtain  500 , a so-called central curtain, whose two ends  510  and  520  are integral with a first ram  100 , and which is connected to the second ram  100 ′, so that the relative movement of a ram  100  or  100 ′ relative to the other ram  100 ′ or  100  along a first movement axis, i.e., the X-axis illustrated here, extends along the vertical plane defined by the X and Y axes by about one length of curtain  500  between the two rams  100  and  100 ′.  
         [0025]    The device D of the invention has the advantage of continuously providing a flat vertical wall in plane P (X, Y), whatever the position of the two rams. Thus, as shown in the drawing of FIG. 4 a , the two rams  100  and  100 ′ are in the adjacent position and the length of the central curtain  500  separating the machining station situated to the front of rams  100  and  100 ′ and the driving station situated to the rear is minimal, the unused length being retracted to the interior of the machine tool. When the rams  100  and  100 ′ are separated from each other by common or relative movements, the second ram  100 ′ deforms said curtain  500 , so as to present a sufficient separation length between the two stations and between the two rams  100  and  100 ′.  
         [0026]    According to a particularly advantageous characteristic, said central curtain  500  has a fixed length and is deformed by retracting to the interior of the machine tool M the unused length, when the two rams  100  and  100 ′ approach each other, and deploys to the exterior of the machine tool M, when the two rams  100  and  100 ′ are separated from each other. The implementation of a curtain of fixed length avoids the pulling or deformation due to different movements impressed along the X-axis on the two rams  100  or  100 ′ by the driving station. Thus, the curtain  500  is instantaneously deployed or retracted, depending on whether the two rams  100  and  100 ′ are separating from or approaching each other.  
         [0027]    According to a preferred, but non-limiting variant, the second ram  100 ′ has means of retraction  110 ′ and  120 ′, consisting of means of contact that cause the curtain  500  to pass from a vertical position perpendicular to the axes of the two rams  100  and  100 ′, which are parallel to the Z-axis, to a vertical position parallel to said rams  100  and  100 ′.  
         [0028]    According to the invention, each ram  100  and  100 ′ contains on the common movement axis and on its outside a so-called lateral separation curtain that follows the movements of said ram on this axis.  
         [0029]    As shown in the drawings of FIGS. 1 and 2, the device D also consists of two makeup curtains  600  and  600 ′ that function as lateral curtains, each connected to a ram  100  and  100 ′, only the openings of which, prescribed for their effect in device D, are apparent, which ensures separation between the machining station and the driving station, when a space is created during separation a ram  100  or  100 ′ from the lateral wall of machine tool M.  
         [0030]    Thus, the device D of the invention represents a complete solution for separation between the machining station and the driving station.  
         [0031]    To complement this separation solution, each ram  100  and  100 ′ is connected to a mobile carriage  130  and  130 ′, which, by ensuring connection to the ends of said curtains  500 ,  600  and  600 ′, permits guiding of the other curtains  700  and  700 ′, ensuring separation of said stations on a movement perpendicular to the former.  
         [0032]    According to the depicted preferred, but non-limiting variant, device D also consists of a fixed carriage  800  that ensures guiding of said central and makeup curtains  500 ,  600 ,  600 ′, driven by the movements of rams  100  and  100 ′, to which they are associated relative to the frame of machine tool M.  
         [0033]    According to the variant illustrated in the drawings of FIGS. 4 a  and  4   b , the means of retraction  110 ′ and  120 ′ connected to the second ram  100 ′ consist of rollers, a first one of which ensures passage of the curtain  500  from a vertical plane perpendicular to the axes of rams  100  and  100 ′ to a vertical plane almost parallel to said axes, and a second one that causes said curtain  500  to pass from said almost parallel plane to another perpendicular plane, but within machine tool M.  
         [0034]    Thus, when the two rams approach each other, the length of curtain  500  separating the two rams  100  and  100 ′ diminishes to the front and increases to the interior or machine tool M. Inversely, when the two rams  100  and  100 ′ separate from each other, the length of the curtain  500  separating the two rams  100  and  100 ′ increases to the exterior and diminishes by the same amount to the interior of machine tool M, because the curtain has a fixed length.  
         [0035]    According to the variant illustrated in FIGS. 4 a  and  4   b , a first end  510  of the central curtains  500  is connected to the mobile carriage  130  of the first ram  100  and the second end to an attachment tab  140  connected to the interior or machine tool M at the rear of said first ram  100 . The attachment tab  140  has, for its length along the X-axis, the maximum length of the curtain front part. Thus, when the two rams come together, the curtain entrained by said tab is wound around the roller, so as to reduce its separation length between the two rams by the length of travel of the attachment tab  140 .  
         [0036]    The variant shown in the drawings of FIGS. 1 and 2 differs in that the means of retraction of curtain  500  are made by a contact device  530  for the first change in plane, i.e., from the vertical plane perpendicular to the axes of rams  100  and  100 ′, to a vertical plane almost parallel to said axes. Moreover, each ram  100  and  100 ′ contains an attachment tab  140  and  140 ′. According to the variant shown, said attachment tabs each have a length along the X-axis equal to half the maximum length of curtain  500 , deployed when the two rams  100  and  100 ′ are at maximum distance from each other.  
         [0037]    Naturally, it is not essential that the end  520  of curtain  500  itself be fixed to tab  140 , but a cable or other means of transmission of the movement can be, so as not to employ a curtain of unduly bulky length.  
         [0038]    According to a particularly advantageous characteristic, each zone of a change in plane contains a means of sealing of the scraper joint type to avoid introduction of chips into the machine tool.  
         [0039]    It is understood that the separation device D was just described and shown in order to divulge the invention rather than limit it. Naturally, various arrangements, modifications and improvements could be made to the aforementioned example without departing from the scope of the invention, taken in its broadest aspects and essence.