Abstract:
A machine for automatically applying snap fasteners on a support, such as a fabric, comprises a sensor for sensing the instantaneous value of the riveting pressure applied to the machine punch elements. 
     With respect to prior machines for automatically applying snap fasteners, the machine according to the invention provides the advantage that the snap fastener can be applied to a fabric with a proper riveting pressure, so as to prevent both excessive pressures, which could damage the fabric, and insufficient pressures, which could not provide a proper connection of the snap fastener on the support, from being generated.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a novel machine and method for applying pressure or snap fasteners on a support, such as, for example, a fabric material. 
     The field of the invention is that of the machine designed for automatically applying snap fasteners, either made of a metal material or not, and other fittings in general such as rivets, eyelets and the like, on support materials such as fabric, leather, paperboard, plastics materials and the like. 
     In this type of machine it is very important that the two portions forming the snap fastener be mutually clamped by pressure, the so-called “riveting” pressure, which is necessary to hold the snap fastener on its support material, such as a fabric material, without damaging the support material because of an excessive effort. 
     Moreover, it is very important to prevent reduced pressures of efforts which could lock the snap fastener with an insufficient locking or clamping force. 
     On the other hand, the above mentioned operating pressure would be undesirably modified if, because of a changing of the support material thickness, a corresponding variation of the punch element displacements applying the snap fastener portions would not be carried out: in other words, a larger operating displacement or stroke for smaller thicknesses and vice versa. 
     In prior art machines, the above mentioned requirements was met by providing specifically designed systems, such as microswitches or measurement sensors, provided for detecting the displacement or stroke amount of a bottom punch element which, in such an application, would be provided to yield depending on the thickness of the support material to which the two portions of the snap fasteners must be connected. 
     Thus, conventional automatic machines for applying snap fasteners, provides to use a riveting pressure which is indirectly determined, i.e. set depending on the yielding of the punch element under the pressure applied thereby onto the supporting material. 
     The above mentioned systems, however, have the drawback that the disclosed displacement of the punch element would change, for example because of a wear of movable portions or the like, from a set displacement, then the riveting pressure would be consequently undesirably modified to values which would be unsuitable for properly applying the snap fastener on the supporting fabric. 
     Moreover, prior machines are suitable to detect only the maximum riveting pressure, and are not designed to also detect the minimum riveting pressure value. 
     Thus, even if it is assured that the two portions of the snap fastener are not pressed with an excessive force on the supporting fabric, on the other hand it is possible that the minimum value of the riveting pressure is not achieved, which minimum value would be indispensable for preventing the snap fastener portions from detaching from the supporting fabric or material. 
     SUMMARY OF THE INVENTION 
     Accordingly, the main object of the present invention is to provide a novel machine and method for automatically applying snap or pressure fasteners on a support material and which, differently from prior approaches, are specifically designed for applying the snap fasteners with a proper value of the riveting pressure, also in an even and time repeatable manner. 
     Another object of the present invention is to provide a delivery device for automatic machines applying snap fasteners and other metal fittings in general. 
     Actually, prior snap fastener applying machines conventionally comprise a snap fastener or fitting delivery device including: 
     a vessel for holding therein the snap fasteners to be supplied; 
     a feeding and supplying system for feeding and supplying said snap fasteners to a delivery guide means, including either a rotary bell, or a vibrating means, or a swinging arm mechanism; 
     at least a delivery guide means, for sending the individual snap fasteners to a gripper supplying assembly; 
     a gripper supplying assembly including a plurality of loading rods for loading the individual snap fasteners toward a gripper and punch region to apply said snap fasteners to a fabric and the like material. 
     These prior machines are affected by several different drawbacks. 
     At, first, a missing snap fastener in a gripper (for example a male portion of the snap fastener in a top gripper), will cause an application of only a counter-male portion, with a consequent damaging of the fabric material due both to a mechanical action deriving from the applied snap fastener portion and an operation of the operator which must remove from the fabric material said counter-male element already fixed on said fabric. 
     Further drawback is that missing snap fasteners at the end portion of the guide means, due either to an empty condition of the snap fastener feeding vessel or to possible malfunctions and/or lockings inside the guide means. 
     In this case, it would be very important to collect information about the missing said snap fasteners at the end portion of the guide means, and to collect any further information due to possible jammings. 
     In the case of an excessively filled vessel, a further drawback would occur, i.e. that of not sufficiently supplying the snap fasteners in their guide means. 
     Thus, yet another main object of the present invention is to provide a delivery device and related automatic machine for applying snap fasteners, allowing an operator to apply said snap fasteners with high quality operations, thereby protecting the end product from any damages due to not properly feeding the snap fasteners or due to an application of damaged snap fasteners during their delivery step. 
     The above mentioned objects, as well as yet other objects, are achieved respectively by the machine and method as described herein. 
     Preferred embodiments of the invention are disclosed in the dependent claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above mentioned objects, features and advantages of the invention will become more apparent hereinafter from the following detailed disclosure of a preferred embodiment of the machine according to the invention, which has been disclosed, by way of an exemplary but not limitative embodiment, in the figures of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a general view illustrating the machine according to the present invention; 
     FIG. 2 illustrates the machine shown in FIG. 1, by a side view of the operating or driving mechanism thereof; 
     FIG. 3 illustrates a view of the pressure detecting device, applied on the machine shown in FIG. 2; 
     FIG. 4 is a front view illustrating a delivery device applied to an alternative embodiment of the machine according to the present invention; 
     FIG. 5 is a front view illustrating a view of the snap fastener supplying device applied to the machine of FIG.  4 . 
     FIG. 6 is a side view illustrating the delivery device shown in FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 and 2, the machine according to the present invention comprises a supplying and locating system  1  for respectively supplying and locating the snap fastener portions to punch elements, respectively a top punch element  2 , and a bottom punch element  3 , provided on respective faces of a support element  4  provided for receiving said snap fasteners, such as a support fabric. 
     As shown in FIG. 2, the top punch element  2  is driven starting from a crank pin  5  which, in turn, is driven by a suitable motor-reducing unit, not specifically shown. 
     To the crank pin  5  is coupled a rod  6 , pivoted at an end portion  7  of a main lever  8 . 
     The end portion  9  of said main lever  8 , opposite to its fulcrum  10 , or pivot pin, on the machine framework, is coupled to an inner point  13  of a secondary lever  11 , through link elements  12 . 
     The end portion  14  of the lever  11  transmits to the punch element, the driving from the lever  8 , through the transmission shaft  15 . 
     The remaining end portion  16  of the lever  11  is, in turn, coupled to a shaft  17 , including a spring  18  and having its end portion  19  coupled to the framework  20  of the machine. 
     As shown in FIG. 2, the end portion  19  of the shaft  17  coupled to the framework  20  of the machine is provided with a sensor  21 , for example a load cell, designed for sensing the riveting pressure value provided by said shaft  17  to the spring  18 . 
     In addition to the riveting pressure sensing or detecting sensor  21 , the machine according to the present invention can also comprise detecting device for detecting a presence of the snap fastener in a top gripper element (not shown), a presence of a snap fastener in a bottom gripper element (not shown), a passage of the snap fastener to a right guide  28 , and a passage of the snap fastener to a left guide  29  (FIG.  1 ). 
     The operation cycle of the machine starts as the crank pin  5  is driven along its circular path  22 , thereby causing the end portion  9  of the lever  8  to be lowered and, accordingly, a corresponding lowering of the top punch element  2  against the bottom punch element  3 . 
     The pressure applied by the punch element  2  on the support  4  is instantaneously detected or sensed by the pressure sensor  21 , through the assembly or system comprising the secondary lever  11 , shaft  17 , spring  18 , and fixed framework  20 . 
     In particular, an electronic center unit  23  coupled to the sensor  21  indicates, for example on a display  24 , the value of the riveting pressure as detected or sensed by the sensor  21  (see FIG.  3 ). 
     The mentioned electronic center unit  23  is moreover calibrated or set on a maximum riveting pressure value and a minimum riveting pressure value and, outside the pressure range defined between the two mentioned pressure values, said electronic central unit will drive a stop of a following snap fastener applying cycle, while providing on the display  24  an indication of the riveting pressure value which has been achieved. 
     The center unit  23 , in particular, controls the snap fastener application of riveting pressure as follows. 
     At the start of a new operating cycle for making a new cloth article or an article different from a preceding article, the operator carries out test applications, up to find a proper riveting or application pressure. 
     Then, by operating the pressure adjuster  25 , the operator will set this pressure value, thereby the bar display  24  will be switched on to indicate the starting or “0” value (for example at about a half of the display). 
     Then, an alarm and stop adjuster  26  is set, to cause the machine to be automatically stopped as the snap fastener application pressure, as sensed by the sensor  21 , is either excessively high or excessively low, with respect to the programmed or set value, i.e. as said pressure exits the maximum and minimum pressure values as preliminarily set. 
     The reset pushbutton  27  will be pressed for re-actuating the operation of the machine after a stop thereof due to a detection of a riveting pressure different from that set on the mentioned electronic center unit. 
     In particular, the latter will be of a type suitable to detect and store, by the above-mentioned devices, possible stop conditions of the machine, in the time and/or with respect to a preset number of operating cycles, due to missing snap fasteners in the grippers, missing snap fasteners in the guide means, or due to an erroneous value of the riveting pressure (either in excess or less than a preset riveting pressure). riveting pressure (either in excess or less than a preset riveting pressure). 
     The failure data would be made available for a production cycle analysis. 
     Owing to the above disclosed detection system, it is assured that the two portions of the snap fasteners are fixed on the support fabric  4  with the proper riveting pressure, depending on the thickness of said supporting fabric. 
     Moreover, any operations without a presence of a full snap fastener, or of one of the two portions thereof, are prevented. 
     Moreover, possible obstacles, susceptible to be present on the displacement path of the top punch element  2 , are prevented from jamming or locking the proper operation of the machine. 
     The invention as disclosed and illustrated is susceptible to several modifications and variations, all of which will come within the scope of the accompanying claims. 
     Thus, for example, the sensor device used on the subject machine could be arranged at a different location. 
     In particular, said sensor can be also mounted, for example, at the bottom punch element  3  of the machine. 
     FIG. 4 illustrates a four way machine, for automatically applying fittings (for example snap or pressure fasteners) on articles in general (such as fabric, leather, plastic, paperboard materials and so on). 
     This machine essentially comprises a machine base  31  thereon is mounted a machine body  32  including applying means for applying said fittings, as well as a supplying device  33  for supplying the fittings or snap fasteners. 
     The machine also comprises a control central unit  34  which is also designed for collecting data. 
     As clearly shown in FIGS. 5 and 6, the device  33  comprises a tank or vessel  35  for holding said fittings or snap fasteners, said vessel being coupled to a plate  36  provided at the top portion of the guides  52 ,  53 ,  54  and  55  for delivering said fittings. 
     On that same plate  36  is moreover assembled a rotary bell feeder  38  for feeding said fittings, which communicates with the vessel  35  through a communicating opening (not shown). 
     The feeder  38  operates to properly direct the fittings so that they could be supplied inside the mentioned guides, which, in turn, are provided with slotted profiles, thereinto the fittings are caused to fall under the effect of gravity. 
     As better shown in FIGS. 5 and 6, at the end portion  39  of each said guide, the fittings are taken up by pusher elements  40  and  41 , provided for individually feeding said fittings or snap fasteners, into the respective top  42  and bottom  43  grippers. 
     Moreover, as clearly shown in FIGS. 5 and 6, the rotary bell device  44  is driven through a belt  44 ′, in turn driven by a pinion  45 . 
     A first pair of sensors  46  and  47 , designed for detecting the presence/absence of the snap fasteners in the grippers  42  and  43  are provided near said grippers. 
     Preferably, said sensors are of an optic fiber type and are coupled to the above mentioned control central unit  34 . 
     In the case of a missing fitting or snap fasteners, the sensors  46  and  47  will prevent the machine from operating, to alert the operator to manually feed the snap fasteners into the grippers not provided with said fasteners. 
     Thus, the product being processed is prevented from being damaged because of erroneous operations of the machine. 
     Further sensors  48 ,  49 ,  50  and  51  are applied at the respective end portions of the guides respectively indicated by  52 ,  53 ,  54  and  55 . 
     The above sensors are coupled to said central unit  34  and operate to detect the passage or absence of the mentioned fittings or snap fasteners inside the mentioned guides. 
     If a snap fastener would be missing, then the sensor will prevent the machine from operating, alerting the operator to signal, through a dedicated control  37  provided on said central unit  34 , if the malfunction is due to an empty vessel  35  or to a jamming of the snap fasteners inside the guides  52 ,  53 ,  54  and  55 . 
     Owing to the provision of the system including the sensors  48 ,  49 ,  50  and  51  and the control  37  on the central unit  34 , it is possible to record the failure rate of the machine, in each set time period and for each batch to be processed. 
     Moreover, the detection of the presence of fittings or snap fasteners inside the guides, performed by the sensors  48 ,  49 ,  50 , and  51 , in combination with an absence of snap fasteners in the grippers, as detected by the sensors  46  and  47 , provides the operator with a proper signalling of a possible jamming in the snap fasteners supplying at the outlet of the mentioned guides. 
     Further sensors  56  and  57  are finally arranged at the top portion of the vessels  35  and are designed to switch off the operation of the machine, if it exceeded a preset level corresponding to a maximum amount of snap fasteners in said vessels. 
     This would be susceptible to damage said snap fasteners inside the rotary bells  38 . 
     In such a case, the operator will be alerted to lower the level of the snap fasteners, to partially empty their vessels. 
     The above disclosed and illustrated machine, of a four way supply type, can also comprise a different number of operating ways (respectively three, two or a single way), without departing from the scope of the present invention.