Tools – Wrench – screwdriver – or driver therefor – Responsive to movement of work
Reexamination Certificate
1999-12-10
2001-06-05
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Responsive to movement of work
C081S054000
Reexamination Certificate
active
06240816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a depth stop for a hand-held screw driving tool including a housing, a drive located in the housing for rotating a spindle about a spindle axis, and a chuck for receiving a working tool, connected with the spindle and projecting from the housing in an axial direction defined by the spindle axis, with the depth stop including a sleeve-shaped element for surrounding the chuck, connectable with the tool housing and having means for adjusting a length of an axial projection of the depth stop past the chuck.
2. Description of the Prior Art
Gypsum plaster boards, flake boards, or fibrous plates are often directly connected, without preliminary drilling, to a constructional component or the like, e.g., a wooden component, a shaped sheet element or the like, by a hand-held screw driving tool and usable therewith, suitable attachment screws. At that, the constructional component, to which, e.g., a gypsum plaster board is to be attached, need be hit with the screw in order to correctly insert the same. During the attachment, as a rule, the screw is located high above the gypsum plaster board or the like. With improper attachment, the screw need be removed. Therefore, the operator need to carry gripping pliers with which the operator can pull out the screw after laying down the screw driving tool. Besides the necessity to carry the gripping pliers, the operator has to perform an additional operation which interrupts the production process. In addition, when working on a scaffold or the like, putting down the screw driving tool can present a problem.
The screw bits of the hand-held screw driving tools, which are used by professionals, are subjected to a rapid wear and, therefore, need be frequently replaced. For removing the screw bits from a bit holder secured in the chuck of the screw driving tool, a special gripping tool is needed, e.g., pliers with which the operator can grip the screw bit and pull it out of the bit holder. Often, the bit holder itself need be replaced. For this purpose, the operator has to have, as a rule, a separate auxiliary tool. The operator can either carry this auxiliary tool with him/her or interrupt the production process to procure the auxiliary tool. Of course, the interruption of the production process is highly undesirable.
The hand-held tool, as a rule, are equipped with a depth stop which provides for a controlled screwing-in and, e.g., in case of exposure of the attachment point to adverse weather conditions, permits a controlled pressing-on of a sealing washer provided on the fastening screw. With the known depth stops, the operator does not have any possibility to determined, during the setting process, when the sealing washer is placed on the constructional part and, as the case may be, whether it is overstrained by the operational process. As a result a uniform good quality of the attachment points cannot be insured. The pressing-on of the sealing washers cannot be controlled and can result in an inadequate sealing of the attachment points exposed to adverse weather conditions. The overstraining of the sealing washer can result in a sidewise displacement of the rubber coating. This adversely affects the appearance of the attachment points and can lead to reclamation on the part of the customer. Because of this, in many cases, the depth stop is not used. However, non-use of the depth stop, can result in formation of non-uniform and non-accessible attachment points. Furthermore, non-use of the depth stops results in increase of time necessary to form the attachment points.
Accordingly, an object of the present invention is to provide a depth stop in which the drawbacks of the prior art depth stops are eliminated.
Another object of the present invention is to provide a depth stop which would eliminate the need in separate gripping pliers or the like presently used for removing the improperly screwed-in screws from a gypsum plaster board and the like.
A further object of the present invention is to provide a depth stop which would eliminate a need in an auxiliary tool for removing the screw bits and, if necessary, for removing the bit holder.
A still further object of the present invention is to provide a depth stop which can be used with fastening screws provided with sealing washers without adversely affecting the quality of the formed attachment points.
SUMMARY OF THE INVENTION
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a depth stop for a hand-held screw driving tool and including a housing, a drive located in the housing for rotating a spindle about a spindle axis, and a chuck for receiving a working tool, connected with the spindle and projecting from the housing in an axial direction defined by the spindle axis. The depth stop has a sleeve-shaped element for surrounding the chuck, connectable with the tool housing. The depth stop has at least one axially extending opening formed in a wall of the sleeve-shaped element and piercing the wall through an entire wall thickness. The opening has, at its axial end remote from the housing, an entrance region. The depth stop also has means for adjusting a length of an axial projection of the depth stop past the chuck. The at least one opening serves as an auxiliary means for removing an attachment or fastening screw, which permits to remove the screw with the screw driving tool itself. To this end, a screw head projecting above the upper surface of a gypsum plaster board or the like is guided through the entrance region of the axially extending opening into the opening, with the edges of the opening engaging the head from beneath. The screw is pulled out by moving the screw driving tool away from the construction part, i.e., the gypsum plaster board. Thus, there is no need in the gripping pliers, and the operator does need to carry them. Further, there is not necessary to put down the screw driving tool . Providing an opening having an appropriate shape permits to use the depth stop for removing screw bits from the bit holder. To this end, the depth stop need be disconnected from the housing. Thereafter, the screw bit can be clamped in the opening and pulled out. In the same way, the removal of the bit holder takes place. Because the opening pierces the wall through its entire thickness, it permits to control whether and when the sealing washer, which is provided on a screw, abuts the constructional part, e.g., the gypsum plaster board. Thus, there is no reason to remove the depth stop during screwing-in of screws provided with a sealing washer.
An easy guidance of a screw head into the opening is insured when the opening is formed as a slot guide and has at its end remote from the housing, a ramp-shaped entrance region. The screw head can be passed particularly easy through a ramp-shaped entrance region.
According to an advantageous embodiment of the present invention, the at least one opening has a large width at one of its axial ends than at the opposite end. This feature provides for holding of the screw, screw bit, and also the bit holder by clamping the screw, the screw bit or the bit holder in the opening, which permit an easy extraction of the screw, screw bit, or the bit holder.
Providing, according to the present invention, a plurality of piercing openings permits to provide openings having different geometry. This permits to use the depth stop for extraction of different types of fastening screws. In addition, providing a plurality of openings on the circumference of the depth stop permits to select the most appropriate position of the screw driving tool corresponding to respective space requirements for extraction of a particular screw which stipulate an easy grasping of the screw head from beneath.
According to a further advantageous embodiment of the present invention, the depth stop further includes at least one axially extending slot-shaped recess which pierces the wall through its entire thickness and the dimensions of which differ
Ludwig Manfred
Rahmsdorf Horst
Riedl Reinhard
Brown & Wood LLP
Hilti Aktiengesellschaft
Shakeri Hadi
Smith James G.
LandOfFree
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