Patent Publication Number: US-2004051325-A1

Title: Gripping means

Description:
FIELD OF INVENTION  
       [0001] The invention relates to apparatus for locking and unlocking gripper devices lifting and lowering large parts, construction components and the like as defined in the preamble of claim 1.  
       BACKGROUND OF INVENTION  
       [0002] Transporting loads such as slabs or panes made of steel, concrete, plastic or wood, generally speaking large parts, requires hoisting equipment such as pulleys and winches which must move vertically at least at the beginning and end of transportation. Illustratively rope or chain systems are used to seize a load around which they are placed and which they hold in place in frictional/compressive manner during the motion. When this procedure is too cumbersome or only the upper rim shall be accessible, grippers will be used. If enough space is available, wide scissors grippers may be used that shall close upon applying to them an upward traction as soon as a locking pawl allows that motion whereby the load is seized and held between clamping jaws. Thanks to a lever&#39;s mechanical advantage, the compressive force is about twice the load&#39;s weight.  
       [0003] Other gripper equipment such as pipe suspension gear operates by means of a rope or chain system on a generally two-arm lever configuration,spanning the load like a bail and seizing them by the bail ends when a traction, which typically may be twice or three times the weight of the load, is applied by means of appropriate reversing rollers and articulations to a pivoting lever. The British patent document 1,063,857 A describes a gripper of which the traction band or chain system is guided in S-manner over reversing rollers and engages in articulating manner a rocker lever which is prestressed by a tension spring toward a fixed jaw element and which when the load is being lifted will be pressed against this load.  
       [0004] The German patent document 43 39 609 C2 describes a clamping jaw device equipped with at least one safety lever to grip from below plates/slabs which must be transported, said lever automatically opening or being pivoted as soon as the load has been deposited.  
       [0005] Safety regulations moreover require apparatus preventing the grippers or clamps from automatically disengaging from the load when this load no longer is applied. This goal is attained in general by a spring system compressing the movable jaw, which as a rule is a compression plate, against the load. This design entails the drawback, for instance as regards suspensions of multiple rope/cable systems that the clamp or gripper first must be opened using one hand against the spring force and then must be lifted from the load with the other hand. If the loads for instance are manhole rings, then the operator is required to bend widely forward during this work and his spine shall be substantially stressed, entailing significant health risks at weights up to 20 kg (200 N).  
       SUMMARY OF INVENTION  
       [0006] A considerable objective of the present invention is to overcome the above and other drawbacks of the state of the art by means of a simple apparatus supporting opening the clamp/gripper against the spring force and moreover keeping said device open. This apparatus moreover may be manufactured economically and is easily operated. The purpose of the invention is to absorb even large loads while itself being of low overall weight and to be always reliable even under rough conditions of construction.  
       [0007] The main features of the present invention are stated in claim 1. Further developments are the objects of claims 2 through 20.  
       [0008] Apparatus for locking and unlocking grippers raising and lowering structural members, large construction parts and the like that may be clamped by two gripper jaws moving toward each other makes use of a carrying frame in general assuming a ∩ shape and fitted with a rocker lever in such a configuration that a first gripper jaw rigidly joined to the support member is situated opposite a second gripper jaw linked to the rocker lever, a traction element guided along an S path over reversal pins or rollers engaging in particular the upper region of said support member, said traction element initiating clamping forces by the gripper jaws. In the present invention, a latch is mounted on the rocker lever and selectively locks and releases said locking lever. In this manner safety at work is considerably enhanced using simple means, namely in that—using one hand—the rocker lever may be moved out of the locked into the steady open position, and vice versa. Also the load can be clamped and released more quickly than before and substantial time savings are attained, foremost when several transporting tasks must be carried out in rapid succession with that one apparatus.  
       [0009] While the German utility model document 295 10 732 U1 discloses a hoist for manhole-rings which is fitted with a traction or drive rod of which the upper end may be snapped by a prestressed spring latch into one pivoting position, it does not allow freezing the gripper-jaw&#39;s open position. Moreover this design constitutes a clip of which one leg comes to rest perpendicularly against the load and away from a support arm, whereas a second leg mounted in adjustable manner on said support arm shall press by means of an elbow lever a compression element against the load as soon as traction is applied to the pivotable drive rod. This drive rod however is linked to a rigidly affixed extension arm (a compression rod) of the displaceable leg and consequently it is able at best to apply traction on the elbow lever only if the second leg is able to pivot somewhat about the support arm, that is, if it is affixed with chatter play as is the case for simple screw clamps. Another drawback of this design is that in known manhole-ring hoists of the state of the art, the jaws&#39; gripping width is adjustable only discretely and only within a narrow range.  
       [0010] In one embodiment, the articulation of the latch is mounted on that end of the rocker lever of which the bearing is opposite the carrying frame. Consequently the full length of the rocker lever is made use of during locking and unlocking. If now the latch&#39;s articulation is configured near a reversal pin or roller of the rope system, then this rope system may be maximally expanded in the transverse position as regards the open position, and the aperture width or the possible open jaw size of the gripper device will be especially large.  
       [0011] Preferably the latch shall be a rod of which the free end can be locked into or on the carrying frame. Not only is this rod economically manufactured and assembled, but also it is easily seized and handled. To engage a grip of the latch, the carrying frame is fitted at its upper zone and preferably opposite the rocker lever&#39;s bearing with a notch, recess or the like acting as a rest for the latch when in its engaged position. For that purpose the notch, recess or the like is configured next to a suspension slot at the top of the carrying frame where a stop acts as a rocker for the unlocked latch when it is pivoted upward. This feature extraordinarily enhances easy handling.  
       [0012] Operation is made easier furthermore in that the latch articulation is mounted on the rocker lever next to a mating stop and/or next to a reversal pin or roller for the rope or chain system. As a result the latch at the rocker lever&#39;s outer end is configured at a site of operation which is very near the articulation and which offers high leverage for pivoting, in particular because the mating stop and/or the rope or chain system&#39;s reversal pin is situated at the rocker lever&#39;s free end that is opposite the carrying frame&#39;s coupling point. This configuration is selected in a manner that, in the rocker lever&#39;s neutral position, the mating stop, the latch&#39;s articulation and the reversal pin are configured on an approximately straight line and are approximately equidistantly apart and thereby offer especially advantageous handling.  
       [0013] In especially advantageous manner, the carrying frame is fitted with a limit stop for the rocker lever&#39;s free end, as a result of which said lever&#39;s closest or neutral position is very easily implemented. In a special embodiment, the limit stop simultaneously constitutes a reversal pin for the traction element, for instance closely underneath the suspension slot.  
       [0014] A spring may be mounted at the carrying frame in the region of the rocker lever&#39;s bearing to bias said lever toward the neutral position. This spring furthermore ensures that the latched latch is pressed into the carrying frame&#39;s notch. An appropriate spring is a torsion spring enclosing the pivot bearing and resting by its legs on one hand against the carrying frame and on the other hand against the rocker lever. Moreover a tension or compression spring may be used in other embodiment modes.  
       [0015] In claim 14 the invention defines apparatus to grip and also raise or lower planar or curved components, big construction parts and the like which in particular are clamped along vertical lines or surfaces between gripper jaws, said apparatus comprising a generally ∩-shaped carrying frame bearing at one lower end a rocker lever coupled in articulating manner to a gripper jaw, said lever being configured in rigid manner opposite a second gripper jaw, and also comprising a traction element which acts on upper zone fo the carrying frame and which is guided along an S path over reversal pins and which applies clamping forces on the gripper jaws when the gripper device is raised. In this respect the invention provides that a control element shall be mounted on the rocker lever to selectively lock or release said lever, whereby handling is shall be extraordinarily simplified.  
       [0016] In another embodiment, the traction element passing over at least one reversal pin is a belt, for instance an endless polyester belt which drives the lever while spaced away from its pivot axis. Where there are two reversal pins, their separations from each other and/or relative to a affixation point may be made adjustable. Advantageously at least one of the reversal pins and/or the affixation point are suspended in swinging manner in order to accurately guide the traction element and to preclude deformations, pivoting motions etc.  
       [0017] To assure safe handling, advantageously one of the reversal pins shall be configured approximately at the common center of gravity of the gripper device and the construction part. Moreover the reversal pins and the lever&#39;s pivot axis may run substantially parallel to each other. Advantageously the traction element can be suspended from a hoisting element of hoisting equipment such as a crane, excavator, forklift etc. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018] Further features, particular and advantages of the present invention are stated in the claims and in the following description of illustrative embodiments and in relation to the appended drawings.  
     [0019]FIG. 1 is a sideview of a gripper device in its neutral position,  
     [0020]FIG. 2 is a sideview of a gripper device of FIG. 1 in its open position,  
     [0021]FIG. 3 is a sideview of the gripper device of FIG. 1 in its clamping position, and  
     [0022]FIG. 4 is a sideview of pipe suspension with an axial section of a manhole ring seized by two gripper devices. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0023] The partly schematic sideview of FIG. 1 shows a gripper device  10  in its neutral position. A ∩-shaped carrying frame  12  may be fitted in its upper region with a suspension slot  14 . Said frame is fitted at one of its down-facing legs with a stationary gripper jaw  15  and above latter, yet preferably below the suspension slot  14 , with an affixation element in the form of an engagement bolt  16  for a traction part, for instance a rope or chain system Z running upward around a deflection pin or roller  18 . Another leg of the carrying frame  12  is fitted at its lower end with an articulation or bearing  22  for an L-shaped rocker lever  20  supporting at its end a displaceable gripper jaw  45  situated opposite the stationary gripper jaw  15 . At its upper, i.e. outer free end  25 , the rocker lever  20  is fitted with a reversing pin or roller  28  for the traction part Z which runs around it in an S pattern. A torsion spring  24  is used at the articulation or bearing  22  of the carrying frame  12  to bias the rocker lever  20  toward the narrowest, i.e. neutral position.  
     [0024] The gripper device  10  is fitted with an operational system keeping it open and comprising a latch  30  acting as the operational rod. By means of an articulation or tubular bearing  32 , said rod  30  rests on the free end  25  of the rocker lever  20 ; the rod  30  also comprises a grip  34  at its other end. The rocker lever is wholly pivoted backward in FIG. 1 and as a result the displaceable gripper jaw  45  is situated its least distance b from the stationary gripper jaw  15 . The free end  25  of the rocker lever  20  reaches the reversal pin  18  forming a limit stop. In this position the articulation  32  of the latch  30  is near the reversal pin  18 . A mating stop  36  which is mounted at the free end  25  of the rocker lever  20  and also near the articulation  32  limits the downward excursion of the latch  30  to the horizontal end position shown in FIG. 1.  
     [0025] To open the gripper device, ie the clamp  10 , the latch, i.e. the latch  20 , is pivoted upward as indicated by an arrow. Thereupon the limit stop  38  of the carrying frame  12  stops and provides a rest for the rod  30  and consequently a rocker articulation has been created which upon further upward motion of the latch  30  supports the sideways pivoting motion of the rocker lever  20 . In the process the traction element Z guided around the reversal pin  28  is stretched until the end position shown in FIG. 2 is reached wherein the grip  34  snaps into a notch  40  at the periphery of the carrying frame  12 . In this position the gripper jaws  15 , 45  are separated by the maximum distance B, that is the maximal jaw aperture. Actuating the rope system Z, the now locked apparatus may be moved freely without requiring further procedures such as having to manually remove the clamps from the load (T) omitted from FIG. 2. The drawing furthermore shows that the spring  24  is maximally stressed in the direction opposite the force F (FIG. 1). As a result, the clearance  42  of the carrying frame  12  is entirely freely accessible.  
     [0026] Next a load may be inserted, for instance a peripheral part of manhole ring T as shown in FIG. 3. The gripper device is closed by moving the grip  34  against the biasing force F out of the notch  40  and by pivoting the latch  30  rearward, ie outward (FIG. 3), the spring force F compressing the gripper jaw  45 , which is coupled to a tipping bearing  44  of the rocker lever  20  against the load T. Thereupon the latch  30  is able to pivot downward as far as the mating stop  36  (FIG. 4), though it may also continue resting against the carrying frame  12  of the gripper device  10  as indicated by dashed lines in FIG. 3.  
     [0027]FIG. 4 shows how a manhole ring T is seized by two gripper devices  10  as soon as a traction is applied to the rope system Z. The rods  34  being unlocked, the rocker levers  20  have carried out a full pivoting and consequently the springs  24 —which are omitted form FIG. 4—compress the movable gripper jaws  45  against the load T. The traction exerted by the rope system Z additionally compresses the rocker levers  20  and hence the displaceable gripper jaws  45  against the inside wall of the manhole ring T.  
     [0028] The present invention is not restricted to one of the above illustrated embodiment modes, rather it may be modified in versatile manner. For instance the operational surfaces of the gripper jaws  15 ,  45  may be fitted with smooth or fluted rubber coatings, and furthermore buffers made of rubber or other soft materials may be present in the hollow, ie the clearance  42  of the carrying frame  12  in order to protect the surfaces of construction parts T, other big components and the like. Nor is it foremost critical that the spreading device be fitted with a spring or springs because the important point is the ability to raise (and lower) the gripper devices  10  into a stopped position without the need for applying manual force. Again, the rope system Z may be a flat band, for instance an endless polyester belt.  
     [0029] It will be noted that in a preferred embodiment of the present invention regarding locking and unlocking gripper devices  10  used to raise and lower construction parts T, big components and the like which, by gripper jaws  15 ,  45  moving toward each other, can be clamped by means of a rocker lever  20  elastically resting on a frame  12  and mounted on said carrying frame  12  that assumes an overall ∩ shape, a latch  30  is coupled to the carrying frame  20  and allows selectively locking or releasing the rocker lever  20 . The articulation  32  of the latch  30  is situated at the free end  25  of the illustratively L-shaped rocker lever  20  near a reversal pin  28  for a rope or chain system Z by means of which clamping forces can be applied to the gripper jaws  15 ,  45 . Preferably the latch shall be a rod/bar  30  which by means of its free end or grip  34  may snap into a notch  40  configured at the periphery of the carrying frame  12 . Said frame comprises at its top a stop  38  acting as a rocker for an unlocked latch  38  when being pivoted upward. A mating stop  36  captures the unstressed locking bar  30  near a reversal pin  28  of the rope Z. The carrying frame  12  is fitted with a limit stop  38  for the free end  25  of the rocker lever  20  and this stop  38  simultaneously acts as a reversal pin for the rope or chain system Z and is situated tightly below a suspension slot  14  in the upper part of the carrying frame  12 . The distances of the reversal pins  18 ,  28  between each other and/or relative to the affixation point  16  are adjustable in order to match the point of suspension to different centers of gravity or to vary the height of the clamping force. At least one of the reversal pins  18 ,  28  and/or the affixation point  16  may be supported in rocking manner. Pivoting motions of the construction part T or deformations of the traction element Z outside the gripper device  10  can therefore be compensated in problem-free manner. Also the traction element Z may be made of another plastic or textile. Said traction element however must exhibit high resistance to tear and low weight.  
     [0030] All features and advantages, inclusive design details, spatial configurations and method steps based on the claims, the specification and the drawings may be significant for the invention both per se as in the most diverse combinations.