Abstract:
A molded plastic housing is provided with elastic support members extending in a hollow space, and elastically supporting members. These members have an elongated edge running from a first to a second lateral face of the housing, and accessible through a window. A pre-clamp is assembled to the housing, by placing leg portions on either side of the hollow space, with a base portion extending across the edge of the member. The leg portions are deformed to cooperate with the bottom face of the housing to hold the member in the housing.

Description:
[0001]    This application is a national stage application of International Application No. PCT/EP2012/068956, filed on Sep. 26, 2012, the entire contents of which are incorporated herein by reference. 
         [0002]    The embodiments of the present invention relate to a method and system for the manufacture of a razor cartridge. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of Invention 
       [0003]    Mechanical razor heads with movable blades have been described in the past. In such heads, a cutting member is positioned on spring tongues which push it upwards, in contact with a part of the head which defines an upper stop. The position of the blade is to be defined very precisely, since its exposure will greatly affect the shaving performance of the razor head. 
         [0004]    It is a challenge to manufacture such products in a very reliable way, yet cost effectively and with high throughput. 
         [0005]    WO 2010/006654 discloses a suitable way, by which the cutting members are placed into a guard. A plastic cap covers the guard and cutting members and is assembled to the guard by ultra-sonic welding. 
         [0006]    Although this process is very useful when the razor head comprises two plastic parts, which can be each tailored to a specific function, one may alternatively want to reduce the number of different plastic parts (ie reduce the number of molds and the risk of discarding an assembly because only one of the two plastic parts is outside of the acceptable dispersion range). 
       SUMMARY OF THE INVENTION 
       [0007]    To this aim, it is provided a method for the manufacture of assemblies, which includes: 
         [0008]    providing a sub-assembly comprising: 
         [0009]    a molded plastic housing having a front part and a rear part, a first lateral part and a second lateral part, the front, rear, first and second lateral parts defining a hollow space between them, the housing having a top face having a window mouthing into the hollow space, and an opposed bottom face, the housing further comprising elastic support members extending in the hollow space, 
         [0010]    at least one member elastically supported by at least one elastic support member, and having an elongated edge running from the first to the second lateral faces, and accessible through the window, 
         [0011]    providing a pre-clamp, made of a formable material, and having a U-shape with a first and a second parallel leg portions joined by a transverse base portion, 
         [0012]    assembling the pre-clamp to the sub-assembly, by placing the first and second leg portions on either sides of the hollow space with the base portion extending across the edge of the member, 
         [0013]    deforming the first and second leg portions to cooperate with the bottom face of the housing to hold the member in the housing. 
         [0014]    The above method showed able to provide the required levels of accuracy and throughput. 
         [0015]    In the embodiments of the present invention, one might also use one or more of the features defined in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Other characteristics and advantages of the present invention will readily appear from the following description of one of its embodiments, provided as a non-limitative examples, and of the accompanying drawings. 
           [0017]    On the drawings: 
           [0018]      FIG. 1  is a schematic top view of a system usable to manufacture razor heads, 
           [0019]      FIG. 2  is an exploded perspective view of a razor head assemblable by the system of  FIG. 1 , 
           [0020]      FIG. 3  is a perspective partial view of an assembly path, 
           [0021]      FIG. 4  is a schematic view of a blade placement station, 
           [0022]      FIG. 5  is a sectional lateral view of a guard with assembled cutting members along line V-V on  FIG. 2 , before assembly of the clamps, 
           [0023]      FIG. 6  is a schematic lateral view of a pre-clamp usable in the system of  FIG. 1 , 
           [0024]      FIG. 7  is a schematic front overall view of a clamping station of the assembly system of  FIG. 1 , 
           [0025]      FIG. 8  is a perspective enlarged view of the station of  FIG. 7 , 
           [0026]      FIGS. 9 and 10  are partial sectional views respectively through lines IX-IX and X-X of  FIG. 8 , at a first step of the clamping process, and 
           [0027]      FIG. 11  is a view similar to  FIG. 10  at a second step of the clamping process. 
       
    
    
       [0028]    On the different Figures, the same reference signs designate like or similar elements. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0029]      FIG. 2  shows an exploded view of an example of a razor head suitably assemblable by the following process. As shown on  FIG. 2 , according to this example, the razor head is of the type having a guard  1 , three cutting members  2   a ,  2   b ,  2   c  movably (translatably) mounted in the guard under spring action, two lateral clamps  3   a ,  3   b  that cooperate with the bottom face of the housing and retain the cutting members from falling off the guard through the top window. The clamps provide an upper abutment zone for the lateral sides of the cutting members. 
         [0030]    In particular, the guard comprises a front area  61  and a rear area  62  (front and rear are defined by the normal direction of shaving). The front area  61  may comprises a guard bar, and the rear area may comprise a lubrication strip. Between the front and rear areas, a central area  63  defines a hollow space receiving one or more cutting member(s) extending in parallel to one another. The cutting members extend between two lateral areas  64   a  and  64   b  of the guard. The two lateral areas  64   a  and  64   b  extend from the front area  61  to the rear area  62 . 
         [0031]    The guard  1  is also provided with biasing members  65 . These biasing members bias the cutting members toward a rest position. As an exemplary description, biasing members  65  comprise spring tongues. A spring tongue extends from a lateral area toward the center of the guard, sensibly in parallel with the cutting member edge. It also extends from the bottom area toward the top area of the guard, where ‘top’ designates the face normally used for shaving, and ‘bottom’ an opposite face, through which rinsing water and cut hair flow. The cutting member rests on two opposed spring tongues. 
         [0032]    Each lateral portion of the guard is provided with two insertion holes  66 . Such holes are through holes which extend from the top to the bottom area of the guard. For each given lateral portion, an insertion hole is provided on either side of the hollow space. 
         [0033]    The cutting members can for example be of the type ‘blade fixed to a bent support’.  FIG. 5  shows an example. In such examples, a straight blade  90  made of a specific material, and having a sharpened edge, is fixed (for example welded) to a support  91  (which can be made of a specific, but different, material too) which is bent by an angle α of for example between 90° and 135° between its two portions. The edge of the blade is sharpened and coated by a strengthening coating and a lubrication coating. 
         [0034]      FIG. 1  schematically shows an example of a machine which assembles such a razor head. 
         [0035]    The inputs of the machine are a guard feeding station  4 , three cutting member magazines  5   a ,  5   b ,  5   c , and a pre-clamp feeding station  6 . The number of cutting member magazines may vary, for example from 1 to 5. 
         [0036]    The machine  8  comprises a servo-motor  10  which drives stepwise a platen  11  consisting of a plurality of stages  12  (only two stages are shown on  FIG. 1 , but such stages are provided across the whole platen) along an assembly path  13  (rotation about the vertical Z axis hereafter). 
         [0037]    The cycle is made of ⅓ platen movement and ⅔ platen stay. During platen stay, other tools provided along the assembly path  13  are operated under the action of a crankshaft  15  synchronized with the servo-motor  10 . 
         [0038]    The stages of the platen can be loosely connected to one another, floating in the room&#39;s reference frame. 
         [0039]    As shown on  FIG. 3 , each stage  12  of the platen receives a nest  16  which is fixed to the stage  12 . 
         [0040]    The nest comprises a base  17  which has a bottom portion  18  fixed to the stage (through screws), and a receiving cavity (filled with an assembled razor head on one of the nests of the above drawing) shaped to receive the guard. Lateral jaws  19   a ,  19   b  are movably mounted on the base, and are spring-loaded with respect thereto in order to hold the guard  1  in the nest. 
         [0041]    In particular, in  FIG. 9  (which shows the nest holding the guard in the clamp-forming station), it is shown that the guard is borne on the nest in its central part (front and rear bottom extensions of the guard supported by the nest).  FIG. 10 , which shows a parallel section through the nest in the plane of the claws, shows that the bottom of the guard is accessible through the nest there. As shown in  FIG. 3 , the nest is provided with insertion holes at the location of each clamp end, to receive ends of bending claws. 
         [0042]    Back to  FIG. 1 , a first station  71  is a guard placing station  71 . Guards  1  are provided oriented from a vibratory bowler  72  (movement ensured through air jets). A pick-and-place apparatus  23  is used to pick the guard from the delivery line  24  and place it in the cavity of the nest. The delivery line  24  is designed to provide razor guards from the bowler  72  along the correct orientation. 
         [0043]    The pick-and-place apparatus  23  can use an end provided with suction (vacuum) to hold the guard and release it in correct position in the nest  16 . 
         [0044]    Movement of the end can be commanded by the crankshaft  15 . Hence, the end is moved in Z direction (up-down) with a vertically mobile part  73 , which itself is mounted on a horizontally mobile part  74  which moves in the horizontal plane with respect to a fixed frame  75  of the system. Alternatively, movement of the end can be commanded by a servo-motor synchronized with the servo-motor  10 . 
         [0045]    The guard is moved to a first cutting member-placing station  76 . Here, 3 cutting member-placing stations  76 ,  77 ,  78  are used, the one after the other along the assembly path. All cutting member-placing stations are identical. 
         [0046]    As shown schematically on  FIG. 4 , the station comprises an end  29  which is used to grasp the cutting member using vacuum and deliver it to the guard  1 . This part is adapted to fit to the tiny cutting member geometry needed here. The cutting member is delivered through a window of the top face in the internal space. This end  29  is subject to movement along the Z direction and in the horizontal plane as well. A similar command arrangement as for the guard-placing station can be used here. A difference is the Z-stroke which may be smaller, since the cutting member has a smaller Z-extension than the guard. 
         [0047]      FIG. 5  schematically shows a cross-sectional view through the assembled product at this stage, showing the guard carrying three cutting members. 
         [0048]    At this stage, all three cutting members  2   a ,  2   b ,  2   c  are placed in the guard  1 , to provide a sub-assembly, as shown on  FIG. 5 . Each cutting member rests on two spring tongues  67  (one spring tongue on each lateral side of the guard). The natural elasticity of the spring tongues defines the rest position of the cutting member during assembly. 
         [0049]    Control can be provided after the blades are placed in the guard. Control can be performed by pressure switch during each pick-and-place action. If the control does not reveal any problem, the process continues as follows. If the control reveals a problem, the process continues as follows except that the pre-clamps are not delivered (meaning that the following tools will operate ‘empty’ in such case), or the process continues as follows but the head will be discarded after clamp formation. 
         [0050]    The guard with introduced cutting members is moved into the clamp delivery station  32 . It is possible to retain the cutting members inside the head by any additional means. There can be two clamp-providing stations, one for each pre-clamp to be placed on each respective side of the guard. The stations are similar, except for the different locations for providing the pre-clamp (one on each lateral side of the guard). A device similar to the one handling the cutting members can be used. 
         [0051]      FIG. 6  schematically shows the pre-clamp in cross-section as it is provided from the pre-clamp feed station  6 . The pre-clamp  9  is sensibly U-shaped, with a base  81  and two aisles (or leg portions)  82 ,  83 . It is made of a formable material, for example a thin sheet of suitable metal. In the present example, the two aisles  82 ,  83  are identical. Each aisle extends to an end  84 . Each end portion can be tapered (sensibly V-shaped in section transverse to the section of  FIG. 6 ). 
         [0052]      FIG. 10  schematically shows how the U-shaped pre-clamp  9  is placed in the guard, with the base  81  of the pre-clamp covering the blade lateral sides, and the aisles  82 - 83  of the pre-clamp inserted in respective insertion holes  66  of the guards in front of and after the blades (see  FIG. 2 ). One such pre-clamp is inserted on each lateral side of the guard, through a front and a rear insertion holes. 
         [0053]      FIG. 7  is an overview of the clamp-forming station  11 . An articulated arm system comprises a first arm  35  mounted at one end  38  to the crankshaft  15 , and a second end  39  mounted at an hinge  40  to the first end  41  of a second arm  36 . The second arm  36  has its second end  34  rotatably mounted to a fixed base  33 . The second arm  36  is connected to a carriage  37  of the forming tool, in order to cause a back-and-forth translative vertical movement thereof, enabling to shape the U-bent pre-clamp in a precise location in the head. 
         [0054]    In the clamp-forming station  11 , both ends of both U-shaped pre-clamps are bent simultaneously to their final shape. 
         [0055]    As shown on  FIG. 8 , a cam bracket  48  holds the nest which receives the head (the nest is not shown on  FIG. 8 , but the head is shown which is held therein). The cam bracket  48  is provided with a caming surface  49 . 
         [0056]    The forming station comprises a base  42  which is movable up and down under crankshaft command, using the two-link arm system  35 ,  36  as described above. 
         [0057]    The support  54 ′ receives two claw shafts  54 . The claw shafts extend parallel to each other along a horizontal axis and are offset with respect to one another along the normal horizontal axis. The claw shafts are rotatably mounted on the base  42 . 
         [0058]    The base  42  comprises 2 pairs of bending claws  45   a ,  45   b  and  46   a ,  46   b  (one pair for each pre-clamp, one claw of a given pair for each pre-clamp end) which are fixed on a respective claw shaft  54   a ,  54   b.    
         [0059]    A spring  47  extends between the upper ends of two associated claws, and biases the claws of a given pair toward a rest position. Alternatively, a torsion spring could be mounted directly on each claw shaft end. The claw shaft  54  cooperates by caming action with the surface  49  of the cam bracket  48  to cause rotation of the claws which surround the guard and pass beneath it so as to fold/bend the pre-clamp ends to their final bent condition. This is described for the front claws, but applies equally to the rear claws. 
         [0060]    In this final condition, and as shown on  FIG. 11 , the clamp has normally a shape with an end  43  slanted toward the base of the U. The shape of the guard defines this final shape. 
         [0061]    The tool further comprises a holder  50  to maintain the clamp and the guard (the holder  50  contacts only the upper clamp surface  85 ) during the bending action. The holder has a basis  51  mounted to translate on the base  42  of the tool along the Z axis, and a stop  53 . Springs  52  are provided between the holder and the base  42 . 
         [0062]    The station which has just been described operates as follows: The whole cycle is driven by the crankshaft  15  through the arms  35  and  36 . 
         [0063]    Upon a first step of the movement of the base  42 , the basis  51  is moved together with the base  42  until it contacts the upper surface  85  of the pre-clamp and also the stop  53  abuts on a not-shown stop of the frame. This stop of the frame ensures that the holder  50  will stop on its way down in case the nest is empty—without razor head—and so it will not crash on the nest. At this location, the basis  51  forms a load member in contact with the base  81  of the pre-clamp, preventing the pre-clamp from moving upward during bending movement. The stop  53  defines the ultimate exposure of the blades. The stop&#39;s position can be finely adjustable in the Z direction by an operator. Hence, the springs which receive the cutting member might be biased to a requested load at this stage. 
         [0064]    Further movement downward of the base (second step of base movement) will compress the springs  52  in order to provide a retardation effect upon release and also to allow for the further movement of the base downwards. 
         [0065]    As the support moves downward, the claw shafts  54  cooperate with the cam bracket  48 , so that the cam surface  49  causes a rotation of the claw shaft with respect to its longitudinal axis. The rear claw shaft is submitted to a movement symmetric to the above one, with respect to a central plane of symmetry passing vertically between the two axis. Thus, the claws  45   a  and  46   a  are rotated counter clock-wise on  FIG. 9 , and the claws  45   b  and  46   b  clockwise, thereby stretching the springs  47 .  FIG. 11  thus shows a final stage of the bending, where the clamps are rotated into their final position. 
         [0066]    As a third step of the base movement, the claw shafts are rotated in the reverse direction (still by cam action). Upon release, the springs  52  will first be unloaded, without the basis  51  moving upward, thus still somehow maintaining the clamps in place just after bending. Only when the springs are sufficiently uncompressed, the basis  51  will move upwards. 
         [0067]    The apparatus can then be provided with an inspection station. This station can for example be an optical inspection station which will check the presence of the two clamps. If the two clamps are not present, the head will be removed from the nest, and will fall to scrap. If the inspection station does not reveal any problem, the operation continues as follows. 
         [0068]    The machine  8  further comprises an output station  7  which outputs assembled heads to bulk or toward further processing. 
         [0069]    The output station has an actuating means to move the jaws  19  of the nest away from the head against the springing action. The head can be picked-and-placed from the main apparatus to further processing or bulk using a similar pick-and-place apparatus as the one used for pick-and-placing the guard in the nest at the guard-placing station. 
         [0070]    Although an embodiment of such an apparatus has been described in details below, other embodiments appear possible. 
         [0071]    As a variant of the platen embodiment, the servo-motor  10  could drive stepwise an endless belt consisting of many stages  12  along an assembly path  13  (here a straight path along a longitudinal horizontal axis) and back along a return path parallel to and below the assembly path. In such case, the mis-assembled head will not be removed from the nest, but will fall to scrap when the belt returns to its original position. An inspection station can be provided just before the guard-feeding station to check that the nest really is empty. 
         [0072]    Such a system would provide increased modularity, for example in order to add more stations, for example more cutting member insertion stations in order to assemble razor heads with more cutting members. It might just be sufficient to add a few additional stages to cope with the increased length of the path.