Abstract:
A protection mechanism for a machine, used for monitoring and securing the position of doors and/or positionable machine parts, having a central safety bracket movably supported relative to the doors and/or the positionable machine parts, and configured such that it can only be closed when all the doors are closed and all the machine parts are at an operating position, and a central safety switch which monitors the position of the central safety bracket.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to German Application No.102013212125.3, filed Jun. 25, 2013. The priority application, DE 102013212125.3, is hereby incorporated by reference. 
       FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates to a protection mechanism for a machine, in particular, a protection mechanism for a machine used for monitoring and securing the position of doors and/or positionable machine parts so as to prevent a collision of objects and/or persons with moving or rotating machine parts. The present invention also relates to a protection mechanism for a labeler and a cold-glue unit. 
       BACKGROUND 
       [0003]    Machines for handling objects, such as containers or bottles, comprise fast rotating and moving components, which must be protected against contact so as to avoid malfunctions, accidents and injuries of persons. Normally, such machines are provided with a housing, which also provides protection against collisions. Since such machines must, however, be serviced, closable openings and inlets to the housing are provided, which represent a safety risk. Normally, each of the inlets is monitored separately by a suitable sensor system and locked by a locking mechanism, said sensor system and locking mechanism guaranteeing that the housing can only be opened when the machine is out of operation. Alternatively, the sensor system may also cause the machine to come to a standstill when the housing is opened. Such machines normally have a plurality of openings and/or doors, which all necessitate monitoring to guarantee safe operation. 
         [0004]    Exemplarily, European patent application EP-A-2345835 shows a locking and securing device for a working area of a machine. This prior art shows in particular two pivotable flaps or doors in a frame or housing, which serve as a movable protection device e.g. for bottle treatment and processing facilities, such as a labeler for applying labels to bottles or containers, so as to allow access to the machine for servicing, cleaning or maintenance work. In order to guarantee safety, each door is provided with a locking mechanism and a monitoring unit. The monitoring unit guarantees that the moving parts of the machine will be stopped when the door opens. The locking mechanism guarantees that the door will be mechanically unlocked slowly enough for the machine to be at rest when the door is open. Due to the delay occurring when the door is opened by hand, the rotating and moving machine parts can be brought to a standstill gently and, consequently, with little wear. 
         [0005]    These protection devices are disadvantageous insofar as each protection door must be provided with a separate lock switch and the electronics required therefor, whereby the required amount of mechanical and electronic components and wirings is increased. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    It is therefore a general object of the present disclosure to provide, with little mechanical and electrical expenditure, a protection device for machines comprising a plurality of doors, which effectively prevents contact with rotating and moving machine parts and allows gentle stopping of the moving parts. 
         [0007]    More specifically, the object of the present disclosure is to be seen in the provision of a protection mechanism for a cold-glue unit, which monitors and secures not only the position of doors but also the position of a vertically adjustable drive motor for the gluing roller. 
         [0008]    The general object of the present disclosure is achieved by a protection mechanism for a machine, used for monitoring and securing the position of a plurality of doors and/or positionable machine parts. The protection mechanism is characterized by a central safety bracket, which is movably supported relative to the doors and the positionable machine parts and configured such that it can only be closed when all the doors are closed and all the machine parts are at an operating position. In addition, the protection mechanism is characterized by a central safety switch, which monitors the position of the central safety bracket. It is therefore not necessary to secure and monitor each individual door by a separate safety switch and a separate locking mechanism. In addition, the central safety bracket must have sufficiently large dimensions to cover all the doors so that actuating the safety bracket will take one to two seconds, which will suffice to gently stop the moving machine parts before the doors can be opened and the positionable machine parts moved. 
         [0009]    As used herein, “doors” refer to pivotable flaps allowing access to safety-relevant areas of the machine, which entail a risk of accidents or injuries due to fast rotating or moving machine parts. 
         [0010]    According to an embodiment, the central safety bracket is configured such that it is able to assume two end positions for the machine conditions open and closed. In order to increase the operational safety and facilitate handling, the central safety bracket may be fixed at the two end positions by means of a gas spring. 
         [0011]    According to an embodiment, the central safety bracket is configured such that, with the door open, it is blocked and cannot be moved to the closed end position. The central safety switch, which monitors the position of the central safety bracket, will thus be prevented from reporting a closed, i.e. ready-to-operate condition, although a door is still open. 
         [0012]    According to an embodiment, the central safety bracket is configured such that the doors are blocked, when the central safety bracket is at the closed end position. That is, as long as the central safety switch indicates a closed, i.e. ready-to-operate position, it will not be possible to open a door. 
         [0013]    According to another embodiment, the central safety switch is configured such that, when actuated by an operating element for the central safety switch, it allows the machine to operate, and, when not actuated, it blocks operation of the machine. This safety measure guarantees that operation of the machine cannot be started until all the elements occupy their operating position, since the central safety switch is normally open and can only be closed when all the components monitored, i.e. doors and machine parts as well as the safety bracket, are in their operating position. 
         [0014]    According to an embodiment, the central safety switch is attached to the central safety bracket. This is of advantage when the operating element of the central safety switch is attached to a loose cover that can be replaced. Since the less expensive element will be replaced in this case, it will be more cost-efficient to attach the more expensive switching element to the central safety bracket. In this case, it is also guaranteed that the machine can only be put into operation when the replaceable cover has been installed. 
         [0015]    According to an embodiment, the machine is a cold-glue unit, the cold-glue unit comprising a removable protective mask for a label container and at least one inspection door. The operating element for the central safety switch can be attached to the removable protective mask in this case. Since a change of the label format also necessitates a change of the protective mask, the expensive safety switch need not be exchanged together therewith. 
         [0016]    Alternatively, the central safety switch may also be attached to the removable protective mask and the operating element for the central safety switch may be attached to the central safety bracket. This will be of advantage if the label format is exchanged rarely or not at all, since servicing of the safety switch, which is a crucial safety element, will be facilitated in this way. 
         [0017]    According to an embodiment, the cold-glue unit comprises a gluing roller, a drive motor for the gluing roller and a lever for positioning the drive motor at an inspection position and at an operating position. For removing the gluing roller, it will be of advantage to displace the motor to a raised position. This is accomplished in a simple manner by means of a lever with which the motor is vertically adjusted via a system of rods. 
         [0018]    This adjustment must be prevented when the unit is running. Vice versa, putting the unit into operation should only be allowed when the drive motor for the gluing roller is at the lower position, i.e. the operating position. This is accomplished in that the central safety bracket is configured such that the central safety bracket blocks the lever when the drive motor is at the operating position, so that the drive motor cannot be moved to an inspection position when the central safety bracket is closed. Vice versa, the central safety bracket may also be configured such that the drive motor blocks the central safety bracket when the drive motor is at the inspection position, so that the central safety bracket cannot be closed and so that the central safety switch can, consequently, not trigger a contact. 
         [0019]    The above-mentioned special object of the present invention is achieved by a protection mechanism for a cold-glue unit comprising a gluing roller, a vertically adjustable drive motor for the gluing roller, a lever for raising the drive motor to an inspection position, at least one door as an inspection access and a removable protective mask for a label container, the protection mechanism being provided for monitoring and securing the position of the doors, the protective mask and the vertically adjustable drive motor for the gluing roller and comprising the following components: 
         [0020]    a central safety bracket, which is movably supported relative to the doors, the protective mask and the vertically adjustable drive motor and configured such that it can only be closed when all the doors are closed and the vertically adjustable drive motor is at an operating position, and a central safety switch, which monitors the position of the central safety bracket and the presence of the protective mask. 
         [0021]    A plurality of protective doors, a protective mask for the label container and the gluing-roller drive motor can thus be monitored and secured centrally by means of a safety switch making use of a small amount of hardware and wiring. Since a certain amount energy is required for manually adjusting the central safety bracket, several seconds will elapse until a door can be opened, so that, after triggering of the safety switch, there will be enough time for bringing the rotating and moving parts in the interior of the unit to a standstill gently and with little wear. 
         [0022]    In the following, embodiments, further developments, advantages and possibilities of use of the present invention will be explained in more detail on the basis of the figures enclosed. All the features described and/or illustrated, individually or in any combination, are generally subject of the invention, regardless of their combination in the claims or the references to preceding claims. In addition, the content of the claims is made a part of the description. In the figures, 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0023]      FIG. 1  shows a schematic three-dimensional view of a cold-glue unit according to the present invention in a first operating condition; 
           [0024]      FIG. 2  shows the unit according to  FIG. 1  in a second operating condition, with the central safety bracket open; 
           [0025]      FIG. 3  shows the unit according to  FIG. 1  in a third operating condition, with the doors open; 
           [0026]      FIG. 4  shows the unit according to  FIG. 1  in a fourth operating condition in which the central safety bracket is blocked by a first door; and 
           [0027]      FIG. 5  shows the unit according to  FIG. 1  in a fifth operating condition in which the central safety bracket is blocked by a second door. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    The present invention was realized for simplifying and thus improving and rendering safer the protection mechanisms of machines with fast moving and rotating components for protection against collisions with objects or operating staff. It is a central concept of the present disclosure to monitor and secure closable inspection openings and inspection positions of machine components by a central safety bracket in combination with a central safety switch. That is, in the closed condition of the safety bracket it will be impossible to open the inspection doors or to change the position of machine parts. Vice versa, the safety bracket cannot be closed and the machine cannot be started when doors are open and machine parts do not occupy their operating position. 
         [0029]    This concept will exemplarily be described in the following description on the basis of a cold-glue unit used for applying labels to bottles and other containers. This concept of the present disclosure is, however, not limited to cases of use involving a cold-glue unit, but it may be applied to any machine comprising rotating and moving machine parts that are secured by inspection doors. 
         [0030]      FIG. 1  shows a schematic three-dimensional view of a cold-glue unit. In such a unit, rubber-coated gluing pallets have applied thereto a very thin film of glue via a gluing roller made of hardened steel. The pallets pick up the labels from a magazine, apply a film of glue thereto and transfer them then to a gripper cylinder. The gripper cylinder places the labels with precision on the containers as they pass by on a container table. There, the labels are fixed in position and smoothed out by brushes and sponged rollers. The labeled containers are seized by a discharge star wheel and transferred to the conveyor belt. 
         [0031]      FIG. 1  shows the labeling unit or cold-glue unit  10  with a plurality of doors  30 ,  40 , a drive motor  80  for a gluing roller (not shown), a removable protective mask  20  for a label container (not shown), a lever  70  for vertically adjusting the drive motor  80  for the gluing roller, a central safety bracket  50 -A and  50 -B, a central safety switch  60  and an operating element  61  for the central safety switch  60 . 
         [0032]      FIG. 1  shows the cold-glue unit  10  in a condition in which it is ready for operation (first operating condition) and in which all the doors  30  and  40  are closed, the protective mask  20  for the label container has been installed, the drive motor  80  for the gluing roller has been lowered, the central safety bracket  50 -A has been closed and the operating element  61  activates the central safety switch  60 . In  FIG. 1 , the protective mask  20  is shown only schematically without the label container. The protective mask  20  is, however, normally provided with label format-dependent openings (not shown), i.e. a change of label format will also necessitate a change of the protective mask  20 . Being the most reasonably priced part of the central switching unit, the operating element  61  for the central safety switch  60  is therefore secured to the protective mask and the central safety switch is secured to the central safety bracket. The rubber-coated gluing pallets (not visible in  FIG. 1 ) are located behind the protective mask  20 , said rubber-coated gluing pallets picking up the labels from the magazine, applying a film of glue thereto and transferring them to a gripper cylinder (not visible). Previously, the gluing pallets had applied thereto a thin film of glue via a gluing roller (not visible). The gluing roller is located behind inspection door  30 . The component located behind inspection door  40  may e.g. be the gripper (not visible). The central safety bracket consists of an element  50 -A for blocking and unblocking the doors  30  and  40  and the motor  80  and the lever  70 , respectively, and of a fastening section  50 -B through which the blocking element  50 -A is movably supported. The fastening section  50 -B has attached thereto the central safety switch  60  such that it is located above the protective mask  20  so that the operating element  61 , which is attached to the protective mask  20 , will be able to engage the central safety switch  60  and trigger a contact. The blocking element  50 -A is configured such that respective sections of the blocking element  50 -A block the doors  30  and  40  and the lever  70 , respectively. For example, section  51  of the blocking element  50 -A blocks the lever  70 , so that said lever  70  cannot raise the motor  80  when the central safety bracket is closed. Likewise, section  53  of the blocking element  50 -A blocks the door  30  and section  52  of the blocking element  50 -A blocks the door  40 , so that it cannot be opened during operation. 
         [0033]      FIG. 2  shows the cold-glue unit  10  in a second operating condition, in which the central safety bracket is opened, thus unblocking the doors  30  and  40  as well as the lever  70  for raising the motor  80 . In  FIG. 2 , elements which are identical to the elements in  FIG. 1  are identified by the same reference numerals. As regards the explanation of such elements, reference is made to  FIG. 1 . When the central safety bracket is raised to the open position, the central safety switch  60  gets detached from the operating element  61  thus releasing also the protective mask  20 . The contact in the central safety switch  60  is thus interrupted and the rotating parts in the interior of the cold-glue unit are gently decelerated. Since actuating the central safety bracket  50 -A and  50 -B takes one to two seconds, there is enough time for gently decelerating the moving parts, so that the doors  30  and  40  can be opened safely without any risk of injury and the motor  80  can be raised without damage being caused to the unit. The fact that the operating element  61  is secured to the protective mask  20  guarantees that installation of the protective mask  20  will not be forgotten when a change of format of the labels takes place. 
         [0034]      FIG. 3  shows the cold-glue unit  10  according to  FIG. 1  in a third operating condition, in which the doors  30  and  40  are open, the protective mask  20  has been removed and the motor  80  raised by turning the lever  70 . Also in  FIG. 3 , elements which are identical to the elements in  FIG. 1  are identified by the same reference numerals. As regards the explanation of such elements, reference is made to  FIG. 1 . The third operating condition according to  FIG. 3  is reached after operating condition  2  according to  FIG. 2 , i.e. the central safety bracket  50 -A and  50 -B is first moved to the open position and, subsequently, the doors  30  and  40  are opened, the motor  80  is raised and the protective mask  20  is removed. When the protective mask  20  has been removed, the gluing pallets  90  become visible. Since the contact of the central safety switch is interrupted, when the central safety bracket  50 -A and  50 -B is opened, the rotating components, such as the gluing pallets  90  and the gluing roller (not shown), have already come to a standstill and safe servicing with a low risk of injuries is thus possible.  FIG. 3  also shows that, in the raised condition of the motor  80 , the central safety bracket  50 -A and  50 -B cannot be closed, since the motor  80  blocks section  53  of the blocking element  50 -A, so that the central safety switch  60  cannot be operated, when the mask  20  has been installed and the motor  80  raised. It can also be seen from  FIG. 3  that, when the protective mask  20  has been removed, the central safety switch  60  cannot trigger a contact, even if the motor  80  were not raised and would occupy its operating position, since no operating element  61  would be able to engage the central safety switch  60  for triggering the contact. 
         [0035]      FIG. 4  shows the cold-glue unit  10  in a fourth operating condition, in which an attempt is made to close the central safety bracket  50 -A and  50 -B with the motor  80  lowered and the doors  30  and  40  opened. In this case, the door  30  blocks section  54  of the blocking element  50 -A of the central safety bracket, so that the central safety bracket cannot be closed and the central safety switch  60  cannot establish a contact, even if the protective mask  20  is installed and the operating element  61  would be able to engage the central safety switch  60 . 
         [0036]      FIG. 5  shows the cold-glue unit  10  according to  FIG. 1  in a fifth operating condition. As can be seen from  FIG. 5 , the blocking element  50 -A is configured such that, when the door  30  is closed, the safety bracket is blocked via a section  55  on the blocking element  50 -A, so that the central safety bracket cannot be closed. The central safety bracket is therefore configured such that it can only be moved to the closed position when all doors  30  and  40  have been closed and when the motor  80  has been lowered to an operating position. In addition, triggering a contact in the central safety switch  60  will only be possible when the central safety bracket occupies the closed position and when the protective mask  20  has been installed. Operating the cold-glue unit in an open condition is therefore impossible and safety can be guaranteed. 
         [0037]      FIGS. 1 ,  2 ,  3 ,  4  and  5  show a sequence of operating conditions occurring one after the other.  FIG. 1  shows a ready-to-operate condition (first operating condition).  FIG. 2  shows a second operating condition in which the central safety bracket  50 -A and  50 -B has been opened and the contact in the central safety switch  60  interrupted, so that the moving machine parts in the unit are brought to a standstill.  FIG. 3  shows an operating condition in which all the doors  30  and  40  are open, the motor  80  has been raised and the protective mask  20  removed.  FIG. 4  shows a fourth operating condition in which the motor  80  has been lowered again, e.g. after servicing, and an attempt is made to close the central safety bracket, which, however, is blocked by the door  30  and cannot be closed (not yet ready for operation).  FIG. 5  shows a fifth operating condition, a bit later on, in which door  30  has been closed, but door  40  is still open. When door  40  is closed and the protective mask  20  installed, the central safety bracket  50 -A and  50 -B can be closed, so that the operating element  61  can engage the central safety switch  60  thus triggering a contact. In this case, the first operating condition according to  FIG. 1  is re-established.