Tool changing – Tool transfer to or from matrix – Indexing matrix
Patent
1995-01-03
1996-05-07
Briggs, William
Tool changing
Tool transfer to or from matrix
Indexing matrix
91407, 483 36, 483 38, 483 51, B23Q 3157
Patent
active
055140637
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
The invention relates to a machine tool comprising a headstock, at least one tool changer adapted to move production tools between a magazine position and a working position, and at least one fluid power drive cylinder associated with the tool changer as a drive unit, said cylinder having a cylinder housing, in which an axially moving piston is arranged, for whose terminal damping a damping device is provided.
A machine tool of this type is disclosed in the European patent publication 0 205 030 A2.
In the known machine tool the piston frequently has to shift different machining tools with a relatively small and a relatively large weight. It will be clear that in such cases the adjustment of the damping device will only be a compromise. This however means that the degree of damping or braking will often be too weak when handling heavy objects while when handling light objects it will usually be excessive. In order to tackle this problem attempts have consequently been made to provide for additional choking of the feed air at the feed working space of the drive cylinder in order by regulation of the drive fluid under pressure to affect the normal speed and accordingly to affect the transition to the braking action. In practice this does however mean that substantial effort is necessary to match the settings of the speed choke valves and of the damping chokes in order to get the optimum damping performance. It has been found that in practice after only a few attempts at adjustment the user of the equipment will only be able to achieve quite unsuitable setting values, which are not even roughly applicable for the operation in hand.
In known machine tools there is furthermore the disadvantage that the drive valves and any further pilot control valves must be arranged separately from the machine tools with the result that for final assembly of such machine tools complex electrical wiring and pipe fitting operations are required.
Taking this prior art as a starting point one object of the present invention is to create a machine tool of the type initially mentioned, which can be quickly and easily adapted by the user for different damping specifications as required for particular conditions.
In order to achieve this object, in the invention the drive cylinder has a setting device associated with it, by means of which terminal position damping can be switched over between at least two preset values.
Using the setting device provided by the invention in the novel machine tool it is possible for the user to perform a rapid adaptation to various different conditions of use. Even during the manufacture thereof the setting device may be so designed that in the case of certain different conditions of use of the drive cylinder, taking into account intensity of damping dynamic the braked movement, there is an optimum transition from normal movement to damping, braked movement. In accordance with the respective load occurring the setting device merely has to be switched over to the associated speed predetermined value. In most cases it will be sufficient to provide two predetermined values, which on the one hand apply for a low load range and on the other hand for a higher load range.
It is in the special case of machine tools that there is a need for drive cylinders to be mounted in a dependent manner and for machining tools with a greater and a lesser weight to be arranged on the piston rod in succession. In this case it would for instance be possible to so select a first predetermined weight value that the weight range of 1.8 to 5 kg is covered, whereas the second possible predetermined weight range covers the range between 5 kg and 8 kg. Naturally it would be possible to vary the range limits and to arrange for overlap thereof on a case to case basis. For handling small weights the designer will best so proceed that the associated speed predetermined value renders possible a high normal speed, whereas for conveying heavy masses the normal speed will be reduced by the corresponding predetermined speed val
REFERENCES:
patent: 2893354 (1959-07-01), Austin et al.
patent: 3191505 (1965-06-01), Defibaugh et al.
patent: 3431635 (1969-03-01), Balding
patent: 3681829 (1972-08-01), Cupler, II
patent: 3724331 (1973-04-01), Kobayashi
patent: 3789473 (1974-02-01), Pagella et al.
patent: 4034867 (1977-07-01), Akagawa
patent: 5142766 (1992-09-01), Whehrmeister
Grund Peter
Preussler Udo
Stoll Kurt
Briggs William
Chiron-Werke GmbH & Co. KG
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