Abstract:
A cutting hand tool with a pressure indicating means with a sensor which is actuated when the cutting edge is forced onto a material, a processing means receiving a signal from said sensor and sending a signal to a notification means indicating the pressure as soon as a predefined condition is met.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a cutting hand tool with pressure indication for indicating the pressure or force applied while using the tool. 
       BACKGROUND OF THE INVENTION 
       [0002]    Industrial knives have to meet much higher standards than the ordinary knives individuals use in their kitchen. Productivity, and therefore cutting efficiency, need to be kept constant and at a high level. While some industrial plants run 24/7, the lifetime of a blade subjected to intensive use may not exceed a few hours until its cutting edge becomes unsuitably dull. The useful lifetime of a blade depends on the blade material and the material the knife is being used to cut. A blunt blade represents a waste of time and energy, since more force and more time is required to achieve the same result. In addition, a cutting edge may not wear out uniformly, result in dents and nicks in the cutting edge. These in turn can no longer produce a clean cut and the material cut by the blade may be torn instead of cut. Eventually, the knife cannot be used any more and the blade or the complete knife has to be discarded. 
         [0003]    In the context of a hand-held cutting tool, dull blades not only slow down or compromise the quality of the cutting process. The extra force required for cutting also intensifies the strain in the user&#39;s hand and arm and may cause musculoskeletal disorders, more commonly known as Repetitive Strain Injuries (RSI). RSI are classified as occupational diseases in most developed countries. 
         [0004]    In addition, the extra force required during the cut when using a dull blade increases the risk of slipping and also the level of severity of the potentially resulting injury may be higher. Therefore, it is desirable to monitor the sharpness of the blade&#39;s cutting edge in order to identify the stage at which it is no longer suitable for cutting. However, the sharpness of the blade declines gradually and it is difficult for the user to determine when the blade or knife should be replaced. In some cases a visual check of the blade may be sufficient to determine if it is still sharp enough for cutting. However in the case of a uniform wear of the cutting edge of the blade the difference between a sharp cutting edge and a dull blade cannot be determined by the users eye. 
       SUMMARY OF THE INVENTION 
       [0005]    The main object of the present invention is to provide a cutting hand tool including a means for indicating the amount of pressure being applied on the hand tool while it is being used, in order to allow the user to decide when the blade or hand tool must be replaced. 
         [0006]    Another object is to provide a means of showing if a knife or blade is sharp enough for performing a clean cut. 
         [0007]    A further object is monitoring the use of several cutting hand tools to compare the pressure difference for different applications or by different users. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    In the drawings: 
           [0009]      FIG. 1 : Side view of the cutting hand tool 
           [0010]      FIG. 2 a   : Top view of the cutting hand tool where the notification means are lights 
           [0011]      FIG. 2 b   : Top view of the cutting hand tool where the notification means is a display 
           [0012]      FIG. 2 c   : Cutting hand tool where the notification means is a sound source 
           [0013]      FIG. 2 d   : Cutting hand tool where the notification means produces vibrations 
           [0014]      FIG. 2 e   : Cutting hand tool where the notification means emits an electromagnetic signal 
           [0015]      FIG. 3 : Cutting hand tool with a movable blade and a pressure sensor 
           [0016]      FIG. 4 : Cutting hand tool with a fixed blade and a strain gauge 
           [0017]      FIG. 5 : Cutting hand tool with blade guard 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    A preferred embodiment of a cutting tool with pressure indication is described according to the drawings. This preferred embodiment is to be understood as an exemplary embodiment and any detailed description shall not be interpreted as limiting. Alternate embodiments obvious to one skilled in the art will not be described in detail or will be omitted to prevent the relevant details of the invention to be overlooked. 
         [0019]      FIG. 1  shows that the proximal part of the housing  1  has an elongated handle-like shape suitable for gripping with the hand. The blade  2  protrudes out of the distal end of the knife and its lower edge  21  is the cutting edge. During the operation of the knife, the user grips the proximal part of the housing  1  and exerts pressure on the object to be cut via the cutting edge  21 . This pressure is measured with a sensor  3  and the pressure information is processed by a processing means  4 . Then, a notification means  41  provides a feedback to the user about the pressure applied on the cutting edge  21 . 
         [0020]    Any type of notification means  41  may be used, as long as the signal it emits can be noticed by the user and is related to the force he is applying to the knife. 
         [0021]    The notification means  41  may be a visual indicator  41   a , comprising lights or a display as shown in  FIGS. 2 a  and 2 b   . The location of visual indicators  41   a  should be chosen in order to enable their visibility by the user, usually at the top of the distal part of the knife, as shown in  FIGS. 1, 2   a  and  2   b . In cases where a quantitative monitoring is desired, the exact value of the pressure can be shown on a display ( FIG. 2 b   ). Various types of displays can be used, e.g. LCD or LED displays. Alternatively, qualitative information on the pressure applied to the tool may be displayed by lighting different numbers of lights or lights of different colors ( FIG. 1  and  FIG. 2 a   ). 
         [0022]    The housing  1  may also contain a sound source  41   b  like a buzzer or bell ( FIG. 2 c   ) or a vibrating means  41   c  such as a vibration motor ( FIG. 2 d   ). For the comfort of the user, vibrations or sounds should only be generated if the pressure exceeds a certain threshold. However, these acoustic and tactile notification means  41   b ,  41   c  could also be implemented to increase in volume with increasing pressure beyond a certain threshold. This can force the user to immediately stop the activity due to the discomfort created. 
         [0023]    A further possibility is the transmission of the pressure information wirelessly to a readout device  6  such as a display or a smartphone ( FIG. 2 e   ). This transmission may be a simple RF signal or use various other technologies like Bluetooth or NFC. Several knives may be connected to the same readout device  6 , thus allowing a centralized monitoring of the operation of several tools. In such an implementation, it is important that the signal emitted by each knife is distinct from the others in order to be able to identify them. For example, the signal may contain a unique number for each knife. The readout device  6  may be located in the manager&#39;s office or by the maintenance division. In this embodiment, the cutting tool could automatically notify the maintenance division that the blade is dull and needs to be replaced. Likewise, the production line manager could detect incorrect uses of the knife, e.g. a user exerting an excessive force that could lead to RSI (Repetitive Strain Injuries) or non-conform cuts due to careless operation of the user. This monitoring may also serve quality management purposes: by monitoring the lifetime of the blades, the manager may identify defective blade batches or variations in quality between different blade suppliers. 
         [0024]    In a more complex embodiment a combination of one or more of the notification means described above, especially a combination of a local notification means on the cutting hand tool and a wireless transmission of the pressure information. 
         [0025]    There are several ways to detect the force applied on the blade by the user. 
         [0026]    In one embodiment, the blade  2  can be movably attached to the housing  1 , in a manner allowing a small movement of the cutting edge  21  when it is forced onto the material.  FIG. 3  shows the example of a blade  2  which is pivotally fixed to the housing  1  around the pivot point  21 . When the cutting edge  21  is forced onto the material, a force  81  is applied to the blade  2 , which causes its rotation as shown by arrow  82  until it reaches the pressure sensor  3 . So, the pressure sensor  3  is subjected to a force  83  proportional to the force  82  applied by the user on the blade  2 . Potentiometric, capacitive, piezoelectric or any other common type of sensor  3  may be used. 
         [0027]    In another embodiment shown  FIG. 4 , the force applied to the blade  2  can be directly measured on the blade  2  itself by monitoring its deformation with a strain gauge  3 . In this embodiment the force exerted on the blade can be easily deducted from the value of the strain since these two values are proportional and the blade&#39;s strain/force proportionality coefficient can be found by a simple calibration procedure. The advantage of this option is that it doesn&#39;t require any movement of the blade  2 , allowing the blade to be fastened firmly to the housing  1 , which provides a better stability during the cut. Strain gauges  3  are cheap and easy to implement since they just need to be fixed to the surface of the blade  2 . 
         [0028]    In the presented invention, the sensor  3  interacts with a processing means  4  via a connection  42 . This processing means  4  analyzes the signal delivered by the sensor  3  and activates the notification means  41  accordingly. In the case of a display  41   a , the processing means  4  continuously converts the signal delivered by the sensor  3  into a force value and sends the information to the display  41   a . In the case of a binary notification means indicating if the pressure is beyond a threshold value, the processing means  3  only compares the incoming signal to the predetermined threshold, and sends a signal to the notification means  41  if the threshold is reached or exceeded. In one embodiment where the notification means consists of a visual indicator  41   a  with three diodes, e.g. green, yellow and red, the green one is lit under a first threshold, the red one above a second threshold and the yellow one if the determined pressure value lies between these two values. 
         [0029]    The energy required for the operation of the sensor  3 , the processing means  4  and the notification means  41  is preferably supplied by a power source  6  located in the housing  1  of the knife. This power source can be a battery or any other common type of accumulator. 
         [0030]    This description and the accompanying drawings show exemplary embodiments of the invention. The invention, however, should not be interpreted as being limited to these particular embodiments. Variations of the embodiments can be made by those skilled in the art without departing from the scope of this invention as defined by the claims.