Metal working – Plural diverse manufacturing apparatus including means for... – Type of machine
Reexamination Certificate
2000-04-26
2002-04-09
Briggs, William (Department: 3722)
Metal working
Plural diverse manufacturing apparatus including means for...
Type of machine
C082S075000, C409S201000, C409S211000, C409S216000, C451S216000
Reexamination Certificate
active
06367135
ABSTRACT:
TECHINAL DOMAIN
The invention relates to a device for producing relative motion with two translational degrees of freedom between a spindle means and a retaining element.
PRIOR ART
A spindle means is defined below as any kind of machine tool means which comprises a work spindle for producing rotary notion between a tool and a workpiece in order to machine the workpiece with the tool by means of rotary motion. Without explanations otherwise the term spindle is always defined as the work or main spindle of a machine tool. The rotary motion can be executed either by the tool (for example, in a drill press) or by the workpiece (for example, in a lathe).
To move a spindle means translationally with two degrees of freedom in one plane, in machine tool building conventionally a movement device in the manner of a compound slide is used. In doing so, on a first slide which enables a first translational motion along the first linear axis there is a second slide along with a slide drive in order to enable a second translational movement of the spindle means along a second linear axis which is located conventionally at right angles to the first linear axis. In a movement device designed in the manner of a cross slide for a spindle means all the moments and reaction forces which occur in the machining of a workpiece are transferred both to the drive and guide means of the second slide and also to the drive and guide means of the first slide. This results in that the required machine components of the two linear axes which are built on top of one another must be made with stiff guides or bearings in the form of machine bodies which have been made durable in order to achieve the conventionally desired machining precision. One such movement device is thus necessarily bulky and heavy, the great weight of the masses to be moved limiting the dynamics which can be achieved with one such movement device.
To achieve greater dynamics of the movement devices of the machine tools, in recent years so-called parallel machine kinematics have been developed. In a machine tool which is built using the concept of parallel machine kinematics the drives for the different axes of motion are parallel, this in contrast to the aforementioned movement device in the manner of a compound slide which represents one example of a serial machine kinematics. A movement and positioning device based on parallel machine kinematics for a spindle means is for example shown in FIG. 17 of document EP-A2-0 791 438. A spindle means in the form of a sleeve with a main spindle which is adjustable in the Z-direction is held stationary via eight connecting arms in a support frame. The eight connecting arms are coupled on one end to the rotary spindle unit and on the other end to one slide each. All eight slides can each be moved on a linear guide, the eight linear guides being arranged at right angles to the Z-direction. By means of coordinated displacement of the slides the spindle means can be moved in the X-Y plane which is normal to the Z-direction.
Based on the smaller moved masses, the movement device as in EP-A2 0 791 438 enables greater dynamics than the movement devices mentioned above in the manner of a compound slide. To produce a movement device as in EP-A2 0 791 438 however greater construction effort is necessary. A total of eight linear guides must be arranged precisely to one another and a total of sixteen hinges must be aligned parallel to one another; this is complex in terms of production engineering and is accordingly expensive. Moreover, the construction space which is necessary for the movement device is large relative to the useful working space. Furthermore there are—as is typical for parallel machine kinematics—certain unfavorable states of the movement device in which for a small motion in a desired direction excessively large compensation motions of individual slides are necessary. This is the case in the movement device as in EP-A2 0 791 438 for example when one connecting arm includes a flat angle with its assigned linear guide and the spindle means must be moved essentially perpendicularly to this linear guide.
DESCRIPTION OF THE INVENTION
The object of this invention is to devise a device for producing relative motion with two translational degrees of freedom between a spindle means and a retaining element. The movement device should be simple to produce and dynamic and moreover should have a high ratio of useful working space to the required construction space.
According to the invention a device for producing relative motion with two translational degrees of freedom between a spindle means with a spindle which bears the first part of a first pair of parts formed from a workpiece and a tool and a retaining element for holding the second part of the first pair of parts has a first base part to which a first part of a second pair of parts which is formed from the spindle means and the retaining element is attached. The movement device furthermore comprises a second base part, at least one of the two base parts can be moved in a straight line with respect to the other along a linear guide with a first translational degree of freedom. A support for carrying the second part of the second pair of parts is coupled to the second base part to be able to swivel by means of a swivel joint around a swivel axis which is located at right angles to the linear guide such that the second part of the second pair of parts can be moved by actuating the swivel joint with a second translational degree of freedom on a circular path.
The reaction forces and moments which are formed in the machining of the workpiece with the tool are accommodated by the swivel joint which is made stiff-and massive. The stiff swivel joint enables articulated motion with exactly one rotational degree of freedom. It offers all other movements largely unyielding resistance based on its stiffness. This guarantees that essentially simply reaction forces are transmitted to a drive means for movement with the second translational degree of freedom (i.e. to a drive means for actuating the swivel joint) and act in the direction of this motion with the second translational degree of freedom. All other reaction forces and moments of the reaction forces and moments which are formed in the machining of the workpiece with the tool are accommodated by the stiff swivel joint. The drive means for the second translational degree of freedom must therefore be made stiff only in that direction in which they actuate the joint. Therefore the drive means for the second translational degree of freedom compared to the corresponding drive means can be made light in a movement device designed in the manner of a compound slide.
In the production of a movement device according to the invention essentially only a single swivel joint must be aligned with great precision at right angles to the linear guide. This means a great simplification of production compared to production of a movement device as claimed in EP-A2-0 791 43. Because the second part of the second pair of parts must be borne by the support from only one side, with a movement device according to the invention moreover a greater ratio of the useful working space to the required construction space can be achieved than with a movement device as in EP-A2-0 791 438.
The linear guide of the movement device of the invention can be located on a base structure. The base structure can consist of a housing of a machine tool, a support frame, an installation platform or another basic structure. It defines simply the reference base for the relative motion of the movement device of the invention. The linear guide can be located on the base structure horizontally, vertically or at any oblique angle. By the arrangement of the linear guide at such a oblique angle in the case of workpiece machining especially advantageous fall of chips can be achieved.
One movement device according to the invention is characterized preferably by drive means for actuating at least one base part which can move along the linear guide, which means
Geiger Michael
Meier Peter
Treib Thomas
Briggs William
Mikron SA AGNO
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