BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a tool for effecting drilling and/or chiseling and including a tubular shaft provided, at its one axial end, with a cutting head and having an axially extending through-channel, and a connection member provided at another axial end of the shaft and equipped with a shank, with the connection member having a cross-bore opening into the through-channel of the shaft.

[0003] 2. Description of the Prior Act

[0004] A tool of the type described above is used for drilling and/or chiseling in stone, concrete, brickwork and other similar brittle materials. Tools of this type are known in the which the drillings or chips are removed from a drilled or chiseled bore via at least one helical groove provided on the tool shaft.

[0005] A tool formed as a suction drill is disclosed in German Publication DE 198 10 192A1. The known tool is insertable in a hand-held mechanized tool having a suction device connectable with a vacuum generating device, such as vacuum cleaner or the like, and including a housing surrounding the tool. The tool has a tubular shaft having an axially extending through-channel. A connection member is provided opposite a front end of the shaft for connecting the shaft with the housing of the suction device. The connection member has a cross-bore opening into the through-channel of the shaft.

[0006] The drilling capacity of the suction drill, to which relatively little impact energy is transmitted in a hand-held mechanized tool, functions unsatisfactory. In the known tool, the shaft is screwed into connection member. In the region of the separation of the connection member with the shaft, the energy becomes lost, and a large mass is concentrated in the connection member region which leads to the reduction of the drilling capacity.

[0007] A tool is known in which the connection member and the shaft are formed as a one-piece member. In this tool, the diameter of the connection member is substantially larger than the diameters of both the shaft and the shank.

[0008] The large diameter of the connection member leads to mass accumulation in the region of the connection member, on one hand, and on the other hand, results in a need for an increased machining of the blank in the region of the shaft and the shank during manufacturing of the tool. Thus, the mass accumulation in the region of the connection member leads not only to a reduced drilling capacity but also to increase manufacturing costs.

[0009] Accordingly, an object of the present invention is to provide a suction tool with an increased drilling capacity.

[0010] Another object of the present invention is to provide a suction tool having reduced manufacturing costs.

SUMMARY OF THE INVENTION

[0011] These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a tool the connection member of which has, along a substantial portion of its axial extent, a diameter that at most corresponds to 1.6 of the shank diameter.

[0012] The dimensioning of the diameter of the connection member in relation to the diameter of the shank prevents or at least substantially reduces the mass accumulation in the region of the connection member. This insures a better impact energy transmission which favorably influences the drilling capacity of the tool. Simultaneously, the manufacturing costs are reduced as the diameters of the connection member and the shank differ insignificantly and, therefore, when the connection member and the shaft are formed as a one-piece member, the amount of machining is substantially reduced. Also is reduced the loss of material.

[0013] If in addition to the optimization of the drilling capacity, in particular, when the connection member and the shaft are formed as a one-piece member, the reduction of the manufacturing costs is also of a major importance, preferably, the diameter of the connection member is so selected that it corresponds to 1÷1.2 times of the diameter of the shank. This reduces the amount of machining to a bare minimum and permits to achieve an optimal cost-effectiveness of the tool manufacturing.

[0014] To further provide for cost-effective manufacturing of the tool, the diameter of the connection member at least corresponds advantageously to the diameter of the cutting head. In addition, such dimensioning of the diameters of the connection member and the cutting head insures an optimal operation of the suction device.

[0015] By forming the connection member and the shaft separately and by connecting them by using a conventional joining technique, due to fixed connection, substantial manufacturing advantages are achieved, as well as a reduction of mass accumulation in the region of the connection member which permits to optimize impact transmission between the shank and the cutting head. The use of the conventional joining technique provides for a cost-effective manufacturing of the tool by permitting the use of simplified equipment.

[0016] Preferably, the connection member and the shaft are connected by soldering, gluing, welding, and shrinking. The foregoing methods permits to provide a rigid, durable and, at the same time, cost-effective connection.

[0017] Advantageously, the connection member and the shaft are formlockingly connected with each other, which permits to obtain a constructively simple and, at the same time, cost-effective connection.

[0018] The novel features of the present invention, which are considered as characteristic for the invention, are set forth 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.