Gear cutting – milling – or planing – Milling – Including means to infeed rotary cutter toward work
Reexamination Certificate
2000-12-27
2003-06-24
Howell, Daniel W. (Department: 3722)
Gear cutting, milling, or planing
Milling
Including means to infeed rotary cutter toward work
C408S234000, C409S206000, C409S235000
Reexamination Certificate
active
06582168
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a machine tool consisting of at least one tool spindle which can be moved and positioned in at least one working plane by a movement system.
The above-mentioned machine tools are well known in the engineering industry. They are often used in transfer lines, assembly centres, machining centres and the like. They are characterised by a high degree of flexibility and moveability and are capable of carrying not only one but a plurality of tool spindles simultaneously, the tool spindles also driving various tools for example. It is also known to connect intelligent tool replacement systems or tool magazines to the machine tools in order to increase the efficiency of such machine tools.
The tool spindle is to be positioned in relation to the tool in at least one plane, the working plane, by a movement system. It is also quite possible to position the machine tool in relation to further axes. There are, for example, so-called stages with X and Y movements in which a first carrier has a second carrier which can be moved on the first carrier and therefore provides a movable movement system for the tool spindle at least in one plane. These arrangements are also known as “Cartesian machines”, in other words the relevant axes of movement are arranged at right angles to one another.
The disadvantage with this development is that the first carrier has to be designed so as to be very large as it has to carry and bear not only the weight of the tool spindle and the working force to be exerted but must also in addition bear the weight of the second carrier. On the basis of this principle, this leads to relatively large and heavy machine tools.
On the basis of this known principle, large drive units have to be provided in order to accelerate the high masses in a tolerable amount of time, so the machining times cannot increase too greatly. Therefore, not only the bulky design of such a machine tool but also the more complex drives required lead to increased costs in such machine tools.
The object of the invention therefore is to provide a machine tool, as described at the start, which is simple and economical in terms of production and simultaneously permits a high machining speed.
BRIEF SUMMARY OF THE INVENTION
This object is achieved with a machine tool, as described at the start, in which the movement system comprises at least two guide rods which are connected to one another in an articulated manner by a guide rod joint, each of said guide rods having a free end, said free ends of the guide rods being moveable in opposite relative directions towards and apart from one another and/or in the same direction as one another.
The constructional assembly of parts of the movement system on top of one another is avoided as a result of this concept of the movement system. The two guide rods, which are connected to one another by a guide rod joint, effect a movement in the working plane of the tool spindle. Depending on whether the guide rods move towards one another or apart from one another, the work spindle moves in a first dimension. If the two guide rods move in the same direction, a second dimension results which is arranged at right angles to the first dimension and therefore defines a substantially freely determinable working face which can be covered by the tool spindle. A relative movement of the two guide rods towards one another is also sufficient for the first dimension, in other words, one guide rod can, for example, also remain stationary. A similar effect can be achieved through appropriate selection of the guide rod lengths and the arrangement of the guide rod joint on the guide rods.
The tower-like stage arrangement with X and Y movements of the machine tools results from the proposal according to the invention and a considerably simpler machine tool is produced with considerably lower masses as these no longer have to mutually support one another. This means that not only a smaller number of components is possible—only two guide rods which are connected in an articulated manner and which can be moved towards one another are substantially required for this purpose, and also, owing to the lower masses, smaller and therefore more favourable drives are required in order to achieve the same accelerations according to Newton's law of motion. The tool spindle is therefore positioned with smaller drives in the same amount of time, so the cost of the drive for the movement system is lower than that of the known stage arrangements with X and Y movements whilst retaining the same speed.
The invention does not prevent more than just two guide rods being provided according to the invention. The same also applies to the number of guide rod joints. It is possible, for example, to use the above-mentioned principle in the context of scissor kinematics and the like, for example.
In a preferred development of the invention, it is provided that the guide rods rest on the same plane. As an alternative to this, it is of course also possible to mount the guide rods at different levels in order to achieve specific geometric relationships. Similarly, according to the invention, it is also conceivable that the arrangement is mounted not only on one plane—it is also possible in the same manner that the guide rods are arranged so as to be suspended on a plane or supported on a plane extending substantially vertically. Appropriate guides are provided for the guide rods for this purpose.
Furthermore, it is favourable if the guide rod is mounted in an articulated manner on a guide rod base by a base joint. In the process, the guide rod base forms for example the slide on a track for movement of the guide rod. In order to achieve appropriate stability of the machine tool, it is obviously provided that the guide rod base can be mounted on a plurality of tracks which run in parallel. As an alternative to a guide rod base, and also acting similarly thereto, the guide rod in the lower region rests on a rotatable element, for example a roller or the like, the axis of rotation of this roller is then at the same time also being the axis of rotation of the “base joint”.
A ball spindle, a linear drive, a chain or belt drive, or a rack and pinion arrangement, for example, is provided as a drive for the guide rod or the guide rod base. The drive effects the movement of the guide rods in the same direction or in opposite directions in order to move either the tool spindle in the direction of the track (when moving with one another) or at right angles thereto (when moving in opposite directions to one another). In this case it does not matter whether the above-described drives act directly on the guide rod base or act on parts of the guide rod which are then optionally movably mounted.
The design of the drives is of course very important as the tool spindle is ultimately positioned relative to the workpiece to be machined by precise positioning of the drives. Known control means are used here, the respective geometric relationships being taken into account for positioning of the tool spindle.
In the conventional manner, the drive control is appropriately provided with data by the machine control device in order to execute appropriate positioning. The entire process preferably takes place in this case using microprocessor-aided control devices and is, for example, appropriately carried out in a comprehensively integrated manner in more complex transfer lines or machining centres.
In a preferred development of the invention, it is provided that the axis of rotation of the tool spindle can be oriented or adjusted so as to be parallel, at right angles or at any angle to the axis of rotation of the guide rod joint. In a first embodiment the machine tool is designed as a three-axis machine. The tool spindle can be moved at right angles to the working plane predetermined by the guide rod so the axis of rotation of the tool spindle is parallel to the joint axis of the guide rod joint. It is also possible, however, to select an arrangement at right angles thereto in order to ach
Högl Josef
Windel Fritz
Grob-Werke Dr. h.c. mult. Dipl.-Ing Burkhart Grob e.K.
Howell Daniel W.
Jacobson & Holman PLLC
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