Abrading – Rigid tool
Reexamination Certificate
2000-12-27
2002-06-11
Hail, III, Joseph J. (Department: 3723)
Abrading
Rigid tool
C451S541000, C408S145000
Reexamination Certificate
active
06402605
ABSTRACT:
This invention concerns a drilling device for brittle materials with a drill head detachably fixed to a drilling rod by means of a positive-lock connection.
In practice, such drilling devices are used for drilling glass materials for example. The inherent basic conditions differ so fundamentally from those for processing metallic materials that the use of the same drilling devices is largely precluded. Firstly, an adaptation of the drill head is required to prevent undesirable damage to the brittle material, the drill head usually having several graduated drill bits differently dimensioned in their diameter. Also, the connection between drill head and drilling rod is to be adapted to the special circumstances in the processing of brittle materials. There are two basic objectives faced with this: on the one hand, accurate guiding of the drill head should be realized and thus a close tolerance processing of the material; on the other hand, simple handling of the drill head is to be realized as well.
It is already known from DE-GM 19 13 317 to connect the drill head with the drilling rod by means of a slot and feather design. However, such design of the connection can only insufficiently meet the requirements on the drilling device in terms of the required precision. In particular, it will be disadvantageous that—for the simple replacement of drill bits—a measure of tolerance must be provided for between their boring and the drilling shaft which will inevitably result in deviations of nominal values during the drilling process.
DE 44 34 025 A1, in contrast, shows an altered connection where the drilling rod is screwed on by means of a corresponding thread for fixation of the drill head. In this case, the drill head is aligned by two cylindrical bearing areas, as well as a front stop. Here too, a tolerance measure is to be provided for easy mounting which can result in imprecisions in the drilling process, especially in terms of the comparatively extravagant structure of the drill head and the increased requirements in the processing of brittle materials. Moreover, the screw connection requires considerable expenditure in maintenance and care to prevent premature wear, caused by grainy particles of material which can lead to deposits and thus to damages on the drill head surface.
For increasing the precision to be achieved, it might be conceivable to employ a connection well-proven in metal processing—a chuck for example. However, this will fail in the processing of materials which tend to produce chippings which cannot be comparatively easily removed; it may also fail because of damage to the connection due to deposits or penetrating particles, thus precluding any reliable continuous use.
Before this background, the invention is based on the task to provide for a connection between the drill head and the drilling rod which on the one hand allows for high accuracy in processing the material, and on the other hand for easy handling. Especially, any premature wear of the connection is to be precluded.
This task is met by a drilling device according to the characteristics of Patent claim
1
. The sub-claims concern especially favorable embodiments of the invention.
According to the invention, a drilling device is provided in which the positive-lock connection between drill head and drilling rod is designed for a reliable transmission of the drilling torque, while an essentially conical shape is provided and insertable into a corresponding receptacle for centric positioning of the drill head on the drilling rod. Thus the drill head, independent of the transmission of the drilling torque, is positioned and centered with high accuracy by means of the conical shape, the drilling torque being transmitted by the positive-lock connection. Accordingly, no thread is required for fixing the drill head, and even comparatively large tolerances do not affect the accuracy of the subsequent drilling process, as the drill head is positioned exclusively by the conical shape. Thus, handling is greatly simplified so that the expenditure on changing the drill head as well as the downtimes of the drilling device in the manufacturing process can be significantly reduced. At the same time, the expenditure on care and maintenance is reduced as the design of the positive-lock connection minimizes the influences of material chippings also in permanent operation. The cleaning of the conical shape, if required, is simple as there are no moving components or undercuts.
In an especially favorable embodiment of the drilling device according to the invention, the positive-lock connection is formed by at least one projection connected with the drill head and by a recess of the drilling rod, the recess accepting the projection. Thus, such a projection, designed for example as a cam, engages in positive-lock into the recess of the drilling rod on fixing the drill head, thus reliably transmitting the drilling torque. Any tolerance measures between recess and drilling are not harmful here, as the contact areas between drilling head and drill rod automatically rest against each other on operation of the drill head. Accordingly, feeding devices designed for example as a chamfering device can be provided for further simplified execution of the connection.
In a simple embodiment of the connection, the positive-lock connection has a claw coupling. Such a connection, also available as a standard component, allows for simple installation and a reliable use of the drilling device in practice. For this purpose, the claw coupling has for example at least two immobile or even mobile claws arresting automatically in operating position, thus preventing any undesirable axial release of the drill head from the drilling rod, for example on drawing the drill head back from the drilled hole.
Another favorable embodiment of the invention serves this purpose especially well as the drilling device features an arrest as a protection against any undesirable relative axial mobility between the drill head and the drilling rod. Here, this arrest or fixing device primarily protects the projection and the recess from getting out of contact, in which case the reliable transmission of the drilling moment is no longer guaranteed. Thus, the arrest, designed for example as a catching or clamping device, serves to protect the connection between drill head and drilling rod to prevent any loosening of the connection. Also stopping bodies designed as a wedge, or a locking pin penetrating the connection are conceivable.
In another especially favorable embodiment of the invention, the arrest has a sleeve which engages into a thread of the drill head or into a thread of the drilling rod. Subsequent to the connection of the drill head and the drilling rod, the sleeve allows them to be non-positively braced against each other, precluding any incidental loosening. At the same time, the sleeve designed as a hollow nut encloses the connection, thus allowing for sealing or at least for improved protection against any penetrating particles. Here, the sleeve is arranged freely rotatable either at the drill head or at the drilling rod, with limited axial mobility in the direction of the respective remaining component. For fixing, the sleeve is slipped over the connection, engaging by rotation into the respective thread, the opposite end of the sleeve sitting against a stopper.
In another especially practical embodiment of the invention, the arrest simultaneously engages into a thread of the drill head and into a thread of the drilling rod, with the two threads having countercurrent pitches. By the arrest thus engaging into the countercurrent threads, the drill head can easily be braced against the drilling rod, a good sealing effect and thus an improved protection of the connection enclosed by the arrest being achieved as well. To disengage the connection, the arrest is simply rotated into the opposite direction, drill head and drilling rod being separated. In this way, the disengagement is comparatively effortless even if the connection has to be disengaged against
Bierstedt Henning
Christiansen Uwe
Hail III Joseph J.
Hecaeus Quarzglas GmbH & Co. KG
Ojini Anthony
Tiajoloff Andrew L.
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