Field of the Invention

The present invention relates to a device according to the preamble of claim 1.

Background of the Invention

When one wishes to level out plane or countersunk joints between plates or other plane surfaces with putty compound; today simple putty knives are usually used having varying width, consisting of a handle and a metal sheet with straight edge fixed to the same.

This tool is easy to manufacture, easy to keep clean and works well when filling different plane surfaces; but when filling joints, both countersunk and plane, such as gypsum wallboards and also other plates, this putty knife is not perfect. Since the wet putty compound sinks when it dries the wet putty compound should, already when performing the first filling, have a slight excess height when filling a countersunk joint. Also at plane joints a certain less excess height is desirable for obtaining a good result. For obtaining a good result with an ordinary putty knife, as described above, it is required that the practician must have good feeling and long experience so as to obtain a good result with reasonable effort.

For obtaining an excess height with an ordinary putty knife one has to load the putty knife unevenly from both directions so as to obtain an excess height at the centre of the joint and here is formed an undesirable peak which must be given a finishing treatment.

This has been observed and resulted in different patents of which SE-466409 is one example how to solve this problem.

However, there is a need in the art for an improved solution to the above stated problems.

Summary of the Invention An object of the invention is to provide a solution which mitigates or solves the drawbacks and problems of prior art solutions.

Another object of the invention is to achieve a putty tool which offers a possibility also to less experienced users to be successful with its filling and to offer the professional the possibility to faster and easier obtain a good result, this without any significant change of the traditional simple design of the putty knife and the way of using the same.

The mentioned objects are achieved by a device for applying putty compound, the device comprising a handle and a flexible blade with a straight sharp edge attached to the handle. The blade is arranged to be bent more easily in the middle portion than at its external portions.

Further applications and advantages of the invention will be apparent from the following detailed description.

Brief Description of the Drawing

Figure 1 illustrates an embodiment of a device according to the present invention.

Detailed Description of the Invention

What one wishes to obtain is a putty knife which at the putty blade in right angle or close angle to the substrate scrape off excess putty compound straight but which the more the putty blade is tilted leave a curved profile of the wet putty compound, still with complete scraping off at the external edges of the putty knife. This problem has been solved by the present invention by providing a blade of the putty knife which in its central part gets a desired weakness and at the filling is turned away more by the resistance from the wet putty compound than the ends of the same. The result is a curved filling profile and a soft transition to adjacent plates. According to an embodiment of the invention this is achieved by arranging the blade so that the external portions 3 of the blade 2 have a larger flexural resistance than its middle portion 4. The change in flexural resistance can be made by giving the blade varying thickness, but this alternative is at metal blades so complicated that it probably only will be used at blades of plastic or rubber. The putty knife may also be formed in such a way that the middle portion of the blade is made wider than at the external edges and in this way obtain a larger deflection. This would involve that the fastening to the handle must be made more or less curved or still be straight, but the blade is stiffened at the external edges of the handle and or directly in the blade. An easier way to solve the above mentioned problem at blade having uniform thickness is to make openings or weakenings in its middle portion, with position and length so that the flexural resistance is decreased in a desirable way. Another way is to shape the blade so that the fastening to the handle does not get the same flexural stiff fastening as the external edges at a certain length. Of course, it is possible to combine the above solutions.

Figure 1 illustrates an embodiment of the present invention in which a putty knife has a handle 1, with a flexible blade 2 attached to the handle. Further, the blade has a straight sharp edge 5 by which the putty compound is applied. Moreover, the blade 2 is in its external portions 3 flexural stiff mounted to the handle 1, while its middle portion 4 is cut out and does not reach into the handle further than that the blade 2 here does not have or has a less flexural resistance than at the external portions 3 of the blade. In this embodiment, the blade is attached to one straight edge of the handle and extends along mentioned edge.