Turning – Lathe – Tool rest
Reexamination Certificate
2001-02-07
2003-06-17
Banks, Derris H. (Department: 3722)
Turning
Lathe
Tool rest
C407S035000, C082S161000, C030S167000, C030S168000
Reexamination Certificate
active
06578457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hand-operated toolholder for a chisel and including a holding member for operating a chisel and having a protection flange at its end facing in a direction opposite to an operational direction, and a tubular guide for axially guiding the chisel and received in the holding member.
2. Description of the Prior Art
Hand-operated toolholders of the type described above are used for guiding of chisels, with blows being applied to the longitudinal end of the chisel, which faces in the direction opposite to the operational direction of the chisel. The blows are applied with a hand-operated hammer.
The tool or chisel holder of the above-described type are used for chiseling works on sites where no current is available, for finishing chiseling operation, or for touch-up works required for an unknown constructional component.
A hand-operated toolholder of the type described above is disclosed in German Publication DE 2 610 663A1. The known toolholder consists of a onepiece tubular plastic holder that, e.g., receives a chisel. The guide portion is formed, e.g., of four webs extending in the inner space of the holder and surrounding the chisel, with the chisel being held due to frictional engagement with the surrounding it webs. As the blows are not always applied exactly in the center of the end surface of the chisel, a blow can result in the injury of an operator's hand holding the toolholder. To prevent this, a protection flange is provided at the end of holder subjected to the hammer blows. The protection flange covers the hand of the operator holding the toolholder.
The known one-piece, hand-operated toolholder can be economically produced, however, its drawback consists in that it does not always insure the reliable holding of the chisel. The frictional engagement of the chisel with the holder can result in an uncontrolled sliding of the chisel in the holder, in particular, when the chisel is subjected to an increased loading.
Another drawback of the known toolholder consists in that a reaction feedback develops between the chisel and the hammer with which blows are applied to the chisel. As a result, the operator feels a kick each time a blow is applied to the chisel with the hammer.
Accordingly, an object of the present invention is to provide a handoperated toolholder for a chisel that would permit to separate a hand-operated hammer from the chisel.
Another object of the present invention is to provide a toolholder for a chisel which would insure a reliable guidance of the chisel in the holding member.
A further object of the present invention is to provide a modified toolholder for a chisel which can be economically produced.
SUMMARY OF THE INVENTION
These and other objects of the present invention, which will become apparent hereinafter are achieved by forming the guide portion of the holder as a tubular guide and by providing a locking mechanism which cooperates with the tubular guide for retaining the chisel.
The present invention permits to use chisels, which are used in conventional hand-held mechanized tools. The advantage of these chisels consists in that their standardized shanks provide for optimal guidance and permit their use in various tools. At the same time, the shanks provide for their use with a suitable toolholder and for reliable guidance therein. In order to insure a reliable guidance, the chisel guide in the inventive toolholder is formed as a tubular guide. This type of a chisel guide corresponds to those used in hand-held mechanized tools. The locking mechanism prevents a chisel from falling out and, thus, provides for easy handling of the hand-operated toolholder according to the present invention with a chisel used in conventional hand-held mechanized tools.
The locking mechanism advantageously includes an actuation member that at least partially surrounds the tubular guide and is displaceable against a biasing force applied by a resilient element, and a radially displaceable locking member.
The locking member, e.g., extends into the guide groove of a chisel shank and, thereby, prevents the chisel from falling out of the tubular guide as the axial displacement of the chisel is limited by end walls of the guide groove of the chisel. The radial displacement of the locking member provides for an easy replacement of a chisel in the inventive toolholder. The replacement is effected by displacing the actuation member from a position, in which it holds the locking member in engagement with the chisel shank, into a position in which the locking member can be axially displaced. The resilient member guarantees that the locking member provides for limited displacement of the chisel during operation.
Advantageously, the locking member is so formed that it functions without any disturbances and can be cost-effectively produced. The locking member is arranged in a radial bore which is formed in the tubular guide. The radial extent of the locking member advantageously exceeds the thickness of the wall of the tubular guide. This insures that the locking member can always be displaced through the bore.
Advantageously, the locking member is formed as a spherical member. The spherical shape of the locking member prevents the locking member from jamming in the radial bore of the tubular guide and provides for easy manufacturing of the locking member and simplifies the assembly of the toolholder.
Because, advantageously, the actuation member is displaced, against the biasing force, in the chisel operational direction, the user can displace it by applying force to the flange of the holding member, which contributes to easy handling of the inventive toolholder.
For cost-effective manufacturing of the actuation member, it is formed as a sleeve. When the actuation member is formed as a sleeve, the tubular guide also serves as a guide for the actuation member.
Advantageously, the actuation member has a pocket for receiving the locking member in its released position. The pocket has a depth which at least corresponds to a difference between the radical extent of the locking member and the tubular guide wall thickness.
Because, advantageously, the locking mechanism is axially spaced from end of the tubular guide facing in the direction opposite to the operational direction of the chisel, the space between the facing in the opposite direction end of the tubular guide and the locking mechanism can be used to accommodate an anvil therein which would separate, decouple, during the chiseling operation, the hammer from the chisel. In addition, the use of an anvil prevents deformation and/or material fatigue of the chisel.
Advantageously, the tubular guide has stop shoulders spaced from each other and cooperating with mating shoulders provided on the anvil for limiting axial displacement of the anvil.
In addition, the stop shoulders prevent the anvil from falling out of the tubular guide. Still further, the anvil, because of its limited axial displacement, prevents overloading of the locking mechanism.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments when read with reference to the accompanying drawings.
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Bleasdell Don
Hilti Aktiengesellschaft
Sidley Austin Brown & Wood LLP
LandOfFree
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