Patent Publication Number: US-5297340-A

Title: Parting tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a parting tool for cutting seams, threads or the like, in particular, a parting tool with an arc-shaped blade located between two tines of unequal lengths to make a cut. The long tine has a thorn-like tip and the short tine a spherical thickening above the blade, and the tines pass into a shaft fastened to one end of a shaft mounting. 
     2. Description of the Related Technology 
     German Published Application 1 093 754 discloses a parting tool with a mechanism located in front of the blade to press the seam apart and to guide the parting tool in the uncut part of the seam and having a configuration such that a lateral cut into the fabric is prevented. The pressing apart of the seam and the tensioning of the threads of the seam is still effective in the part of the parting tool at which the threads run up against the blade, whereby the threads are guided to the blade in a manner such that the drawing cut desired is obtained. The parting tool is simple enough so that fundamentally only one tine is required. 
     German Patent 32 31 934 discloses a combination tool for the parting of fabric seams and the removal of threads and parts of threads. The parting tool shaft exhibits a cutting tool at one end and a pair of tweezers at its other end, which may be extended from and retracted into a casing. The casing length therefore corresponds to the shaft length with its two tools located at the ends of the shaft. When not in use, both tools are retracted into the casing. It is not possible to further reduce the size of the combination tool. 
     U.S. Pat. No. 2,710,448 discloses a cutting tool that may be extended and retracted. The smallest length of the tool therefore corresponds to the size of the casing. No further diminution is possible. 
     It is known from the general state of the art to reduce the size of small tools, for example, pocket knives, by making the blades pivotable at their ends. The back sides of the blades protrude slightly from the casing, so a notch in the blade may be engaged by a finger nail, a coin or the like to fold the blades out of the knife casing. This procedure is often difficult, particularly if the tool has not been used for a period of time; it is then very difficult to open. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a parting tool of the aforementioned type, which may be reduced to a minimum size, when not in use, and having tools securely lodged in a casing. 
     This object may be attained according to the invention by providing a parting tool including a shaft holder with a cutting blade shaft at one end of the shaft holder and a pressure surface oriented perpendicular to the cutting blade shaft, which is located at the other end of the shaft holder. A rotation axle may be located at a defined distance in front of the pressure surface and aligned perpendicularly to the blade. The rotation axle may be rotatably mounted in the lateral surfaces of a casing open within the pivoting range of the shaft mounting. The specially designed pressure surface, which is provided with fluting, serves to move the blade together with its shaft into both its working and rest position in a simple manner. 
     The location of the pressure surface used for actuation at a defined distance from a rotation axle of the shaft mounting results in a pivot lever, so that the parting tool may be folded out and in very easily. 
     According to one embodiment of the invention, the upper edge of the casing has a recess, in which the pressure surface is supported in the working position of the parting tool, flush with the upper edge. The casing thus forms an actuating handle for the parting tool, without interference by the pressure surface. 
     The recess in the casing upper edge in this embodiment advantageously has a bevel sloping toward the lateral surfaces, so that a comfortable point of attack is provided for moving under the pressure surface and pivoting in the blade with its tines. 
     The outer surface of the pressure surface is conveniently provided with fluting. 
     A stop is located within the casing to serve as the terminal point abutment for the parting tool shaft in the pivoted in or rest position. 
     According to the invention the stop may be a spring elastic element, which cooperates with the lower and rear rounded ends of the shaft mounting in a clamping manner during the pivoting process and in the extended working position or state of the shaft. 
     The rear end of the shaft mounting may have a groove or notch which is engaged by a cam or nose provided on the stop, in the terminal position of the shaft mounting. This results in a secure hold for the working position, so that accidental pivoting is possible only with the application of a larger force. 
     The rotation axle in the shaft mounting is located in an advantageous manner at a distance of about 2/3 of the total length of the parting tool, measured from the point of the long tine to the end of shaft mounting, thereby obtaining both a favorable lever for the extension and retraction process and a minimum length of the entire parting tool in the folded position. 
     Each of the outer walls of the casing include a recess to receive the ends of the rotation axle and hold the parting tool, so that the working tool is well secured in the hand during the working process. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the parting tool in the closed state from below; 
     FIG. 2 shows the parting tool in the closed state in a lateral elevation; 
     FIG. 3 shows the parting tool in the closed state in a top elevation; 
     FIG. 4 shows the parting tool in the opened state in a lateral elevation; 
     FIG. 5 shows the casing of the parting tool without the cutting blade in a longitudinal section; 
     FIG. 6 shows the casing of the parting tool without the cutting blade in a lateral elevation; 
     FIG. 7 shows the pressure surface from below; 
     FIG. 8 shows the pressure surface in a lateral elevation; 
     FIG. 9 shows the shaft mounting with the axle and the pressure surface from behind; 
     FIG. 10 shows the shaft mounting with the shaft and the two tines in a lateral elevation; and 
     FIG. 11 shows the shaft mounting with the shaft and the tines in a top elevation; 
     FIG. 12 shows the upper edge of the casing including the bevel; 
     FIG. 13 shows the parting tool in the working position with the pressure surface in abutment with the upper edge of the casing; 
     FIG. 14 shows the upper edge of the casing including the bevel according to another embodiment of the invention; and 
     FIG. 15 shows the parting tool, according to another embodiment of the invention, in the working position with the pressure surface supported flush on the upper edge of the casing; 
     FIG. 16 shows a sectional view of the parting tool casing along the line I--I in FIG. 12. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-4 show the complete parting tool 1 including a casing 2, a shaft mounting 3 rotatably supported around axles 4. A cutting blade 9 is fastened with its shaft 5 to one end of shaft mounting 3. A pressure surface 6 may be provided at the other end of shaft mounting 3 to carry out the in- and out-pivoting of the cutting blade 9 with its shaft 5 and shaft mounting 3. 
     FIG. 1 shows the parting tool 1 in the pivoted-in state from below. Casing 2 is closed on one side to limit 7 to receive cutting blade 9. For the pivoting motion of shaft mounting 3, casing 2 is provided with bilateral slot shaped opening 8. 
     FIG. 2 shows the parting tool in a lateral elevation and in the folded state of the cutting blade 9 as in FIG. 1. A holding bearing 10 may be provided for the axle 4 of the shaft mounting 3. An offset recess 11 in the form of a step is located around holding bearing 10 on both sides of the casing. These recesses serve to receive the tips of the index finger and thumb of a person working the parting tool 1. This provides a good hold and guidance of the parting tool. 
     A notch 12 may be located under the pressure surface 6 at the outer end of the shaft mounting 3. In the open working state of the parting tool 1, when the shaft mounting 3 pivoted in, notch 12 engages a spring elastic element 14 (see FIGS. 3 and 5), thereby immobilizing shaft mounting 3 for the working process. Shaft mounting 3 may also exhibit a rounded rear end 20. 
     FIG. 3 shows the parting tool, in the closed state as in FIGS. 1 and 2, in a top elevation. 
     FIG. 4 shows the parting tool 1 in a lateral elevation as in FIG. 2, but with the cutting blade 9 pivoted out in the working position. The shaft mounting 3 is located within the casing 2, with the pressure surface 6 slightly protruding from the casing in this embodiment, so that it may be readily gripped for the pivoting motion. In a further embodiment (See FIG. 15), the upper edge of the casing exhibits a recess, in which the pressure surface 6 is supported flush with the upper edge of the casing, in the working position of parting tool 1. 
     The head of the parting blade shaft 5 is provided with an arc-shaped cutting blade 9 located between two tines 15, 16 of unequal length to effect the cut. The long tine 15 may have a thorn-like point and the short tine 16 may have a spherical thickening 17 above the blade. The tines 15, 16 pass into the shaft 5, which is fastened to one end of shaft mounting 3. 
     FIG. 5 shows casing 2 of parting tool 1 in a longitudinal section without a built-in shaft mounting 3. A stop 13 is integrally joined with casing 2. Stop 13 has a spring-elastic configuration at its upper end and exhibits a nose 18 which cooperates with the notch 12 in shaft mounting 3 (FIG. 2), when the shaft mounting is in the casing 2 according to FIG. 4. A recess 22 is provided in both internal walls of the casing 2. These recesses serve to guide the axle 4 of the shaft mounting into the holding bearing 10 during assembly. 
     FIG. 6 shows a lateral elevation of casing 2, again without a built-in shaft mounting 3. 
     FIGS. 7, 8 and 9 show pressure surface 6 in a top elevation (FIG. 7), a lateral elevation (FIG. 8) and in a cross section (FIG. 9). As seen in FIG. 8, the surface of pressure surface 6 has a fluting 19, thereby appreciably facilitating its manipulation. 
     FIG. 10 shows shaft mounting 3 with tool shaft 5 and two tines 15, 16, without a casing, in a lateral elevation. Tine 15 may exhibit a thorn-like point, and tine 16 may exhibit a spherical thickening 17. FIG. 11 shows the same shaft mounting in a top elevation. 
     FIGS. 12-15 show additional embodiments of the invention. FIGS. 12 and 13 show an embodiment of the parting tool, wherein the upper edge of the casing may include a recess or bevel 21 sloping toward the lateral surfaces of casing 2 and extending below the surface of the casing upper edge. According to the embodiment set forth in FIGS. 12 and 13, when parting tool is in the working position, pressure surface 6 is supported by and in abutment with the casing upper edge. FIGS. 14 and 15 show another embodiment of the invention, wherein pressure surface 6 is located flush with the casing upper edge. Thus, the casing forms an actuating handle for the parting tool and the pressure surface does not interfere with the operation of the parting tool. According to the embodiment shown in FIGS. 14 and 15, casing 2 exhibits a recess 21a and a bevel 21b. 
     According to both embodiment bevel 21 or 21b, respectively, is located beneath pressure surface 6 so the user may place a finger or implement in bevel 21 or 21b, respectively, to facilitate returning the parting tool from the working position to the closed or rest position. 
     The shaft mounting 3 may be introduced in a simple manner into the casing 2. The lateral walls of the casing are elastic and therefore hold the axle 4 in a clamping fashion. 
     The parting tool according to the invention makes possible, together with a minimal length in the folded state of the cutting blade, the safe and protected containment of the sensitive, pointed and thus dangerous tool and the rapid and simple unfolding of the shaft mounting. The parting tool according to the invention has a single part, so that no protective cap can be lost, and it is an integral component of the tool. 
     The illustrated embodiments are shown by way of example. The spirit and scope of the invention is not to be restricted by the embodiments shown.