Abstract:
A web cutting device, which achieves cost reduction by a simplified structure, ensures operational stability, and enhances the reliability of the device, is provided. The web cutting device is equipped with a knife for cutting a web, and comprises: a cutting blade support member supporting the knife and supported to be pivotable between a standby position and a cutting position; a return spring for urging the cutting blade support member toward the standby position; a stopper pin and an engaging groove for stopping the cutting blade support member at least at the standby position; a cutting blade bearing member provided with a slit for receiving the knife, and a knock bolt for pivoting the cutting blade support member to the cutting position; and drive means, composed of an L-shaped lever and an air cylinder, for moving the cutting blade bearing member toward and away from the cutting blade support member.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a web cutting device of a rotary offset printing press for applying printing to a web. 
       BACKGROUND ART 
       [0002]    With a rotary offset printing press for applying printing to a web, when breakage of the web (paper breakage) occurs, the web wraps around the circumferential surface of a blanket cylinder because of adhesion of ink. This has led to an accident such as damage to a cylinder bearing or a cylinder shaft of the blanket cylinder. 
         [0003]    As disclosed in Patent Document 1, etc., therefore, a web cutting device for cutting the web at the same time that the breakage of the web is detected is provided on the travel path of the web (for example, between respective printing units and between a final printing unit and a dryer). By so doing, the length of the web wrapping around the blanket cylinder is minimized, whereby an accident such as damage to the cylinder bearing or cylinder shaft of the blanket cylinder has been avoided. 
         [0004]    In the web cutting device of Patent Document 1, as shown in  FIGS. 7 and 8 , an elongated frame  100  is installed to cross the travel direction of a web W, and a passage space  101  for passage of the web W is provided within the frame  100 . This passage space  101  accommodates a blade  102 , an elongated pedestal  103  facing the blade  102 , and an approach mechanism  104  for bringing the blade  102  close to the pedestal  103  within the passage space  101  in order to cut the web W. 
         [0005]    The approach mechanism  104  includes link rod assemblies  105   a  and  105   b  arranged symmetrically with respect to a plane P parallel to the travel direction of the web W. Each link rod assembly  105   a  or  105   b  has a first link rod  107  connected to the frame  100  via a first support shaft  106 , and a second L-shaped link rod  110  joined to the first link rod  107  by a second support shaft  109  at a control joint (connecting portion)  108 . The blade  102  and at least one press  111  extending parallel to the blade  102  are joined to the second link rod  110  in a coupling arrangement via a slot  112  and a third support shaft  113  and a support shaft  114 . At least one operating jack  115  is present which has ends joined to the control joints  108  (second support shafts  109 ) of the link rod assemblies  105   a  and  105   b.    
         [0006]    According to the above-described configuration, when the web W is to be cut, the first link rod  107  and the second link rod  110  shift from a folded (closed) state to an extended (opened) state as the operating jack  115  extends. As a result, the press  111  and the blade  102  descend within the passage space  101  to approach the pedestal  103 . At the very time when the first link rod  107  and the second link rod  110  have maximally extended (when the spacing between the press  111  and the pedestal  103  has fully narrowed), the blade  102  jumps downwardly (outwardly) of the press  111  to cut the web W (see the standby state of the blade in FIG.  7 →the cutting state of the blade in  FIG. 8 ). 
         [0007]    In the manner mentioned above, with the web cutting device of Patent Document 1, at the time of breakage of the web W, the web W is instantaneously cut to minimize the length of the web W wrapping about the blanket cylinder, thereby preventing the occurrence of an accident such as damage to the cylinder bearing or cylinder shaft of the blanket cylinder, and also preventing an operator&#39;s hand from being injured by the blade  102  jumping out. 
       CITATION LIST 
       [0008]    [Patent Literature]
   [Patent Document 1] European Patent 0686505   
 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0010]    With the web cutting device of Patent Document 1, however, the approach mechanism  104  comprises the link rod assemblies  105   a  and  105   b  each including the first link rod  107 , the second link rod  110 , the first to third support shafts  106 ,  109 ,  113 , the support shaft  114 , and the slot  112 . Since the structure is thus complicated and the number of the components is great, the problem has arisen that a cost increase is entailed. 
         [0011]    Furthermore, holdback may occur at the junction of the first and second link rods  107  and  110  connected by the second support shaft  109 , the junction of the second link rod  110  and the press  111  connected by the support shaft  114 , or the junction of the second link rod  110  and the blade  102  connected by the third support shaft  113 . Hence, the reliability of the web cutting device has been low. 
         [0012]    It is an object of the present invention, therefore, to provide a web cutting device which achieves cost reduction by a simplified structure, ensures operational stability, and enhances the reliability of the device. 
       Solution to Problem 
       [0013]    A web cutting device according to the present invention, intended to solve the above-mentioned problems, is a web cutting device equipped with a cutting blade for cutting a web, comprising: 
         [0014]    a cutting blade support member supporting the cutting blade and supported to be pivotable between a standby position and a cutting position; 
         [0015]    an elastic member for urging the cutting blade support member toward the standby position; 
         [0016]    a position restricting member for stopping the cutting blade support member at least at the standby position; 
         [0017]    a cutting blade bearing member provided with a blade receiving portion for receiving the cutting blade, and an operating portion for pivoting the cutting blade support member to the cutting position; and 
         [0018]    drive means for moving the cutting blade bearing member toward and away from the cutting blade support member. 
         [0019]    The cutting blade support member may comprise: a body portion having the cutting blade of a saw blade shape secured thereto; support shaft portions annexed to opposite end parts of the body portion and pivotably supported by side frames via bearings; lever portions which are provided on the support shaft portions to extend in a direction orthogonal to an axis of the body portion, and against one end part of each of which the operating portion can be pressed; engaging grooves which are provided in the one end part of each of the lever portions, and with which stopper pins being the position restricting members provided protrusively at the side frames can engage at the standby position and the cutting position; and spring hooks which are provided in another end part of each of the lever portions, and which hold return springs being the elastic members in cooperation with the side frames. 
         [0020]    The cutting blade support member may be entirely shielded by a cover, and an opening allowing cutting edges of the cutting blade to enter and exit may be formed in a lower surface part of the cover. 
         [0021]    The cutting blade bearing member may be a casing-shaped cover opening downward, and a slit as the blade receiving portion may be formed in a top surface part of the cover. 
         [0022]    The cutting blade support member may support the cutting blade of a saw blade shape, the cutting blade bearing member may be a casing-shaped cover opening downward, and many engaging knife holes as the blade receiving portion may be arranged in a row in a top surface part of the cover in correspondence with sawteeth of the cutting blade. 
         [0023]    At least two of the drive means may be provided in a width direction of the web, and each of the drive means may be composed of an L-shaped lever for connecting a stay, which is provided to span side frames, to the cutting blade bearing member located above the stay, and an air cylinder interposed between an intermediate part of the L-shaped lever and the stay. 
         [0024]    The L-shaped levers may be provided frontward and rearward as a pair, upper end parts of the L-shaped levers may be joined by separate pins to side surface parts of a casing-shaped cover opening downward as the cutting blade bearing member, while lower end parts of the L-shaped levers may be joined by the same support shaft to the stays provided frontward and rearward as a pair, and a leading end of a piston rod of the air cylinder may be joined by the same support shaft to the intermediate parts of the L-shaped levers provided frontward and rearward as a pair, while a base end of a head of the air cylinder may be joined by the same support shaft to the stays provided frontward and rearward as a pair. 
       Advantageous Effects of Invention 
       [0025]    According to the above-described web cutting device concerned with the present invention, the cutting blade bearing member is approached and moved to the cutting blade support member and, at a later stage of this movement, the cutting blade support member is pivoted by the operating portion. Because of such a simple structure, an injury to the operator is prevented, and the web can be reliably cut. The simplification of the structure results in cost reduction. Moreover, the stability of operation is ensured, and the reliability of the device is enhanced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0026]      FIG. 1  is a sectional front view of a web cutting device showing Embodiment 1 of the present invention. 
           [0027]      FIG. 2  is a sectional bottom view of the web cutting device. 
           [0028]      FIG. 3  is a sectional plan view of the web cutting device. 
           [0029]      FIG. 4-A  is a sectional view taken along line A-A in  FIG. 1 . 
           [0030]      FIG. 4-B  is a sectional view taken along line B-B in  FIG. 1 . 
           [0031]      FIG. 4-C  is a sectional view taken along line C-C in  FIG. 1 . 
           [0032]      FIGS. 5(   a ) to  5 ( c ) are operating state views of the web cutting device, in which  FIG. 5(   a ) shows the position of a knife when a clearance is 10 mm,  FIG. 5(   b ) shows the position of the knife when it contacts the web, and  FIG. 5(   c ) shows the position of the knife when cutting the web, while pressing it down, up to a stopper. 
           [0033]      FIG. 6  is a sectional plan view of a web cutting device showing Embodiment 2 of the present invention. 
           [0034]      FIG. 7  is a sectional front view of a conventional web cutting device during standby of a blade. 
           [0035]      FIG. 8  is a sectional front view of the conventional web cutting device when the blade is cutting a web. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0036]    Hereinafter, a web cutting device according to the present invention will be described in detail by embodiments with reference to the accompanying drawings. 
       Embodiment 1 
       [0037]      FIG. 1  is a sectional front view of a web cutting device showing Embodiment 1 of the present invention.  FIG. 2  is a sectional bottom view of the web cutting device.  FIG. 3  is a sectional plan view of the web cutting device.  FIG. 4-A  is a sectional view taken along line A-A in  FIG. 1 .  FIG. 4-B  is a sectional view taken along line B-B in  FIG. 1 .  FIG. 4-C  is a sectional view taken along line C-C in  FIG. 1 .  FIGS. 5(   a ) to  5 ( c ) are operating state views of the web cutting device, in which  FIG. 5(   a ) shows the position of a knife at the initial stage of pressing by a knock bolt,  FIG. 5(   b ) shows the position of the knife in the course of pressing by the knock bolt, and  FIG. 5(   c ) shows the position of the knife when cutting a web while the knock bolt is pressing the knife. 
         [0038]    As shown in the drawings, a web cutting device  10  of a rotary offset printing press has a cutting blade support member  12  pivotably installed between right and left side frames  11 . A cutting blade bearing member  13  is located below the cutting blade support member  12 , and is supported by front and rear stays  14  as a pair, which are installed between the right and left side frames  11 , so as to be rendered ascendable and descendable by right and left drive means  15  as a pair, in other words, so as to be movable by these drive means  15  toward and away from the cutting blade support member  12 . 
         [0039]    The cutting blade support member  12  has a body portion (holder)  17  in which a saw blade-like knife (cutting blade)  16  is secured, with its cutting edges protruding, to one side of its prismatic body; support shaft portions  19  annexed to opposite end faces of the body portion  17  and pivotably supported by the side frames  11  via bearings  18 ; and prismatic lever portions  20  extending on the support shaft portions  19  in a direction orthogonal to the axes thereof and having lower surface parts on one end side against which knock bolts to be described later can be pressed. 
         [0040]    In an end face part on one end side of each lever portion  20 , there is formed an engaging groove  22  with which a stopper pin (position restricting member)  21  provided protrusively at the side frame  11  can engage at the standby position (see  FIG. 5(   a )) and the cutting (force-cutting) position (see  FIG. 5(   c )) of the knife  16 . In a side surface part on the other end side of each lever portion  20 , there is provided a spring hook  24  for holding a return spring (elastic member)  23  which urges the cutting blade support member  12  (knife  16 ) toward the standby position in cooperation with the side frame  11 . 
         [0041]    A cover  25  entirely shields the cutting blade support member  12 , and an opening  26  allowing the cutting edges of the knife  16  to enter and exit is formed in a lower surface part  25   a  of the cover  25 . A stay  30  for reinforcing the cover is installed to span the right and left side frames  11 . 
         [0042]    The cutting blade bearing member  13  is a casing-shaped cover with an open lower surface. A slit (blade receiving portion)  27  corresponding to the opening  26  is formed in a top surface part  13   a  of the cutting blade bearing member  13 . The aforementioned knock bolt (operating portion)  28 , which can be pressed against the lower surface part on the one end side of the lever portion  20 , is screwed to the top surface part  13   a  of the cutting blade bearing member  13  via a nut  29 . 
         [0043]    The drive means  15  is provided in two sets (optionally, three sets or more) in the width direction of the web W, each of the sets being composed of front and rear L-shaped levers  31  as a pair which connect the front and rear stays  14  as a pair spanning the side frames  11  to the cutting blade bearing member  13  positioned above the stays  14 ; and an air cylinder  32  interposed between intermediate parts of the front and rear L-shaped levers  31  as a pair and the front and rear stays  14  as a pair. 
         [0044]    The front and rear L-shaped levers  31  as a pair have upper end parts joined to side surface parts of the cutting blade bearing member  13  by separate pins  33 , and have lower end parts joined to support plate portions  35  of the front and rear stays  14  as a pair by the same support shaft  34 . The leading end of a piston rod of the air cylinder  32  is joined to intermediate parts of the front and rear L-shaped levers  31  as a pair by the same support shaft  36 , whereas the base end of a head of the air cylinder  32  is joined to the front and rear stays  14  as a pair by the same support shaft  37 . 
         [0045]    A cover  38  shields the side surfaces and lower surface of the cutting blade bearing member  13  and the drive means  15 . Air piping  39  allows air to be supplied from an air supply source (not shown) to the air cylinder  32  and to be discharged from the air cylinder  32 . 
         [0046]    Because of the above-described features, the air cylinder  32  in the drive means  15  of the web cutting device  10  is contracted during ordinary printing to bring the L-shaped levers  31  into a state indicated by solid lines in  FIG. 1 . That is, the cutting blade bearing member  13  is separated from the cutting blade support member  12 . 
         [0047]    As a result, a clearance C adequate as a passage space for passage of the web W is ensured, as shown in  FIGS. 4A to 4C , between the cutting blade support member  12  (its cover  25 ) and the cutting blade bearing member  13  (its cover  38 ), so that the web W can travel therethrough smoothly. 
         [0048]    On this occasion, the cutting blade support member  12  (lever portion  20 ) is restricted to the standby position by the return spring  23 , the stopper pin  21 , and the engaging groove  22 , as shown in  FIG. 4A . 
         [0049]    When the web cutting device  10  cuts the web W in response to the breakage of the web W, the air cylinder  32  in the drive means  15  is extended to pivot the L-shaped levers  31  counterclockwise about the support shaft  34  so that the L-shaped levers  31  are brought from the state indicated by the solid lines into a state indicated by chain lines in  FIG. 1 . 
         [0050]    By the above-mentioned motion, the cutting blade bearing member  13  obliquely ascends (is lifted) as in a so-called parallel link to approach the cutting blade support member  12 , exhibiting behaviors as shown in  FIGS. 5(   a ) to  5 ( c ). 
         [0051]    That is, as the cutting blade bearing member  13  ascends, the aforementioned clearance C which is the passage space for the passage of the web W narrows over time. In the end, the knock bolt  28  is pressed against the cutting blade support member  12  (lever portion  20 ). The clearance C changes from a clearance C 1  (C 1 =10 mm, for example) which defines the knife position at the initial stage of pressing by the knock bolt, to a clearance C 2  which defines the knife position in the course of pressing by the knock bolt, and to a clearance C 3  which defines the knife position when force-cutting upon pressing by the knock bolt. 
         [0052]    These changes from the clearances C 1  to C 2  to C 3  are dependent on the protruding height of the knock bolt  28  determined by the adjustment of the degree of screwing-in of the knock bolt  28 . With these clearances C 1 , C 2  and C 3 , an operator&#39;s hand can be prevented from being injured by the knife  16  jumping out from inside the cover  25  for the cutting blade support member  12 . 
         [0053]    The present embodiment features a simple configuration in which the cutting blade bearing member  13  is approached and moved to the cutting blade support member  12  and, at a later stage of this movement, the cutting blade support member  12  is pivoted by the knock bolt  28 . Because of such a simple configuration, an injury to the operator is prevented, and the web W is reliably cut, whereby the length of the web W wrapping about the blanket cylinder can be minimized. 
         [0054]    Consequently, at the time of breakage of the web W, an accident, such as damage to the cylinder bearing or the cylinder shaft of the blanket cylinder, can be avoided. Moreover, the simplification of the structure of the web cutting device  10  results in cost reduction, and ensures the stability of operation, leading to enhanced reliability. 
       Embodiment 2 
       [0055]      FIG. 6  is a sectional plan view of a web cutting device showing Embodiment 2 of the present invention. 
         [0056]    This is an embodiment in which instead of the slit (blade receiving portion)  27  formed in the top surface part  13   a  of the cutting blade bearing member  13  in Embodiment 1, many engaging knife holes (blade receiving portion)  40  are arranged in a row in correspondence with sawteeth  16   a  of the saw blade-like knife  16 . The other features in the present embodiment are the same as those in Embodiment 1. Thus, the same members as those in  FIG. 3  will be assigned the same numerals as those in  FIG. 3 , and duplicate explanations will be omitted. 
         [0057]    According to the present embodiment, in addition to the same actions and effects as those in Embodiment 1, the following advantages are obtained: During cutting, the web W is held by the sections between the engaging knife holes  40  (i.e., the top surface part  13   a ), so that the web W does not sag, and perforations are formed accurately. Since the web W is pulled forward, moreover, the web W is reliably cut at the perforated area. 
         [0058]    It goes without saying that the present invention is not limited to the foregoing embodiments, but various changes and modifications, such as changes in the structures of the cutting blade support member  12  and the cutting blade bearing member  13 , changes in the shapes of the respective members, a change in the number of the drive means, changes in the actuators, and a change in the structure of the operating portion, may be made without departing from the gist of the present invention. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10  Web cutting device 
           11  Side frame 
           12  Cutting blade support member 
           13  Cutting blade bearing member (casing-shaped cover) 
           13   a  Top surface part 
           14  Stay 
           15  Drive means 
           16  Saw blade-like knife (cutting blade) 
           17  Body portion (holder) 
           18  Bearing 
           19  Support shaft portion 
           20  Lever portion 
           21  Stopper pin (position restricting member) 
           22  Engaging groove 
           23  Return spring 
           24  Spring hook 
           25  Cover 
           25   a  Lower surface part 
           26  Opening 
           27  Slit (blade receiving portion) 
           28  Knock bolt 
           29  Nut 
           30  Stay 
           31  L-shaped lever 
           32  Air cylinder 
           33  Pin 
           34  Support shaft 
           35  Support plate portion 
           36  Support shaft 
           37  Support shaft 
           38  Cover 
           39  Air piping 
           40  Engaging knife hole (blade receiving portion) 
         C Clearance during ordinary printing 
         C 1  Clearance at initial stage of pressing by knock bolt 
         C 2  Clearance in course of pressing by knock bolt 
         C 3  Clearance during force-cutting upon pressing by knock bolt 
         W Web