Abstract:
Disclosed are a novel beam guiding bellows for laser cutting machine, and a method of manufacturing the beam guiding bellows for laser cutting machine, which no longer need a process of placing any special plates such as reflective plates, therefore enabling manufacturing in a shorter time at low costs. The beam guiding bellows is configured by a plurality of stacked sheet bodies integrally folded so as to alternately form hill sections and valley sections, and is thereby made freely expandable and retractable in the overall length as angles of the hill sections and valley sections vary, wherein the inner sheet body disposed innermostly is composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered or reversed, or having, formed on the inner surface thereof, a protective layer composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light, and the inner sheet body has protruding flaps which are formed, automatically in the process of folding it together with the other sheet bodies to thereby form the hill sections and the valley sections alternately, so as to project further inwardly from the apexes of the valley sections.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a beam guiding bellows for laser cutting machine, which is disposed along an optical path of laser cutting machine, and a method of manufacturing the beam guiding bellows for laser cutting machine. 
       BACKGROUND ART 
       [0002]    Laser cutting machine has an optical path along which laser light emitted from a laser oscillator is guided to a condenser lens attached to a machining head, or, for the case where it has a reflective mirror disposed in the middle way between the oscillator and the machining head, it has an optical path from the oscillator to the reflective mirror, and an optical path from the reflective mirror to the condenser lens. Along these optical paths, a bellows is disposed in order to protect the condenser lens and the mirror from being damaged by aerial dusts, or to protect an operator from being irradiated by the laser light. The laser light emitted from the oscillator is, however, not always guided along a straight optical path, but is often diverted or scattered to thereby irradiate the inner surface of the bellows and damage the bellows. One possible reason is ascribable to dust which enters the bellows in the course of expansion and retraction thereof in association with movement of the machining head. The laser light may produce the scattered light by collision on dust which entered the bellows, or on dust adhered on the condenser lens or the reflective mirror, or may reverse the direction of propagation after being reflected on a work typically composed of a metal. The bellows, irradiated by the laser light thus scattered or reversed, is highly causative of burning even if it is made of a flame-retardant material, and such burning of the bellows may consequently result in considerable loss of productivity of the laser cutting machine. 
         [0003]    For the purpose of preventing the bellows from being burnt or damaged-by the laser light, there has been proposed a beam guiding bellows for laser cutting machine, which has reflective plates composed of metal plates made of aluminum or copper, and attached to the inclined portions, between the hill sections and valley sections, of the inner surface of a main bellows component of the beam guiding bellows (see Patent Document 1). According to the beam guiding bellows of a laser cutting machine thus attached with the reflective plates, the risk of burning or damage of the main bellows component, due to the scattered or reversed laser light undesirably incident on the inner surface of the main bellows component, is avoidable since the main bellows component may be protected by the reflective plates. 
       RELATED DOCUMENTS 
     Patent Document 
       [0004]    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-71584 
       DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
       [0005]    The beam guiding bellows for laser cutting machine disclosed in the above-described Patent Document 1 may successfully achieve an effect of the reflective plates, but is very time-consuming for the manufacturing enough to raise the cost, since the reflective plates have to be attached one by one typically by adhesion, on the inclined portions formed in the inner surface of the bellows. 
         [0006]    The present invention was conceived after considering the above-described problems in the conventional beam guiding bellows for laser cutting machine, and the method of manufacturing the same. It is therefore an object of the present invention to provide a novel beam guiding bellows for laser cutting machine, and a method of manufacturing the same, which are capable of not only avoiding a risk of burning or damage of the bellows even if it should be incident on the inner surface thereof by the scattered or reversed laser light, but also no longer needing a process of placing any special plates such as reflective plates, therefore enabling manufacturing in a shorter time at low costs. 
       Means for Solving the Problems 
       [0007]    According to a first aspect of the present invention (invention described in Claim  1 ), aimed at solving the problems, there is provided a beam guiding bellows for laser cutting machine, which is disposed along an optical path of a laser cutting machine for irradiating laser light emitted from an oscillator. The beam guiding bellows is configured by a plurality of stacked sheet bodies, including an inner sheet body disposed innermostly, integrally folded so as to alternately form hill sections and valley sections, and is thereby made freely expandable and retractable in the overall length as angles of the hill sections and valley sections vary. The inner sheet body is composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered or reversed, or has, formed on the inner surface thereof, a protective layer composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light. The inner sheet body has protruding flaps which are formed, automatically in the process of folding it together with the other sheet bodies to thereby form the hill sections and the valley sections alternately, so as to project further inwardly from the apexes of the valley sections. 
         [0008]    According to the beam guiding bellows for laser cutting machine of the first aspect of the present invention (simply referred to as “beam guiding bellows”, hereinafter), since the inner sheet body is composed of material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered or reversed, or has, formed on the inner surface thereof, a protective layer composed of a material capable of protecting the inner layer by absorbing or reflecting the laser light, so that the beam guiding bellows may effectively be prevented from being burnt or damaged, even if the inner sheet body was irradiated by the laser light after being scattered on dust adhered on the condenser lens or the reflective mirror, or after being reversed by reflection on a work typically composed of a metal. Also since the beam guiding bellows has protruding flaps which are formed so as to project further inwardly from the apexes of the valley sections, so that the reversed laser light incident on one of the protruding flaps will no longer irradiate the inner sheet body and the protruding flaps which fall behind (closer to the oscillator than) the irradiated protruding flap. Accordingly, by virtue of the inwardly projected arrangement of the protruding flaps inside the beam guiding bellows, a risk of burning or other damages is more effectively avoidable. 
         [0009]    Moreover, the protruding flaps possibly irradiated by the scattered laser light or the like may be formed (projected) automatically in the process of folding the inner sheet body together with the other sheet bodies to thereby form the hill sections and the valley sections alternately, so as to project further inwardly from the apexes of the valley sections, with no need of attaching any special plates such as reflective plates one by one on the inner surface of the main bellows component already shaped or before being shaped, such as done in the process of manufacturing the conventional beam guiding bellows, so that the bellows may be manufactured within a very short time at low costs. In other words, the beam guiding bellows may be finished at the end of manufacturing of the main bellows component which composes the conventional beam guiding bellows, without needing any succeeding process of, for example, attaching the plates such as the reflective plates. This not only contributes to reduce the number of components and weight as a consequence, but also largely shorten the time of manufacturing. 
         [0010]    The sheet body which composes the beam guiding bellows may be composed of two sheet bodies including an outer sheet body which composes the outer surface (outermost cloth) of the beam guiding bellows and the inner sheet body which composes the inner surface; or may have one or two additional sheet bodies between the outer sheet body and the inner sheet body. Each of the plurality of sheet bodies, but excluding the outermost cloth of the beam guiding bellows, is not always necessarily a continuous sheet body (single sheet body) per a single beam guiding bellows. For example, the inner sheet body composing the first aspect of the invention may be divided into a plurality of parts. The hill sections in the context of the present invention refer to the outwardly protruding flaps of the beam guiding bellows, and the valley sections refer to the inwardly protruding flaps of the beam guiding bellows. The inner sheet body may be good enough if it is composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered or reversed, or having, formed on the inner surface thereof, a protective layer composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered. The material capable of protecting the inner sheet body by absorbing or reflecting the scattered or reversed laser light may be exemplified by those made of anodized aluminum. The material may be used in the form of sheet obtained by rolling a single species thereof (aluminum foil, for example), or in the form of protective layer formed by coating or vacuum evaporation on a sheet-like material. The protruding flaps formed on the inner sheet body are preferably arranged so as to inwardly project from the valley sections located on the both lateral sides, and on the top and bottom sides, for the case where the beam guiding bellows is formed to have an overall geometry of nearly rectangular parallelepiped (cylinder having a square form in the front view). Even in this case, the protruding flaps are not always necessarily formed so as to project out from all valley sections aligned on both lateral sides and on the top and bottom sides, while leaving a part of valley sections without protruding flaps. For example, as described later, the protruding flaps may be formed on every other valley sections aligned in the direction of expansion and retraction of the bellows. 
         [0011]    A second aspect of the present invention (invention described in Claim  2 ) is characterized in that, in the above-described first aspect of the invention, the hill sections and the valley sections are composed of vertical hill sections and vertical valley sections formed on both lateral sides, and transverse hill sections and transverse valley sections formed on the top and bottom sides, and every one of, or every other one of, the vertical valley sections and the transverse valley sections have the protruding flaps formed thereon. 
         [0012]    The vertical hill sections and the vertical valley sections formed on both lateral sides may more specifically be represented by the individual vertical hill sections formed on the left side, the individual vertical valley sections formed between every adjacent vertical hill sections formed on the left side, the individual vertical hill sections formed on the right side, and the individual vertical valley sections formed between every adjacent vertical hill sections formed on the right side. On the other hand, the transverse hill sections and the transverse valley sections formed on the top and bottom sides may alternatively be represented by the individual transverse hill sections formed on the top side, the individual transverse valley sections formed between every adjacent transverse hill sections formed on the top side, the individual transverse hill sections formed on the bottom side, and the individual transverse valley sections formed between every adjacent transverse hill sections formed on the bottom side. In the second aspect of the present invention, every one of, or every other one of, the vertical valley sections and the transverse valley sections have the protruding flaps formed thereon. 
         [0013]    Also according to the second aspect of the present invention, similarly to the first aspect of the invention, not only the main bellows component may successfully be protected and prevented from being burnt or damaged even if the scattered or reversed laser light is incident on the inner surface of the main bellows component, but also the process of arranging the reflective plates will be no more necessary, enabling manufacturing within a short time at low costs. 
         [0014]    According to a third aspect of the present invention (invention described in Claim  3 ) is characterized in that, in the above-described first or second aspect of the invention, the inner sheet body has straight slits formed in portions corresponded to the apexes of the hill sections, or apexes of the vertical hill sections and the transverse hill sections. The straight slits are shorter than the overall length of the hill sections, or the overall length of the vertical hill sections and the transverse hill sections. 
         [0015]    The hill sections herein represent the hill sections which configure the first aspect of the present invention (invention described in Claim  1 ), and the vertical hill sections and the transverse hill sections represent those configuring the second aspect of the present invention (invention described in Claim  2 ). In the third aspect of the present invention, the inner sheet body has the straight slits, which are formed in portions corresponded to the apexes of the hill sections, or apexes of the vertical hill sections and the transverse hill sections, and are shorter than the overall length of the hill sections, or the overall length of the vertical hill sections and the transverse hill sections. Each straight slit may be formed typically by cutting the inner sheet body using a cutting edge so as to have no width, or to have a predetermined width. The apexes of the hill sections, or the apexes of the vertical hill sections and the transverse hill sections, are portions where the folding of the inner sheet body repetitively occurs, as the beam guiding bellows expands and retracts. 
         [0016]    According to the thus-configured third aspect of the present invention, since the straight slits having shorter length than the overall length of the hill sections, or the overall length of the vertical hill sections and the transverse hill sections, are formed in the portions corresponded to the apexes of the hill sections, or apexes of the vertical hill sections and the transverse hill sections, so that the configuration successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the inner sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. The third aspect of the present invention is particularly effective in avoiding the risk of burning or damage of the beam guiding bellows, for the case where the inner sheet body is composed of a simple species of metal such as aluminum foil, since this sort of inner sheet body is causative of heavier (metal) fatigue under repetitive folding in the process of expansion and retraction, so that the dust which floats inside the beam guiding bellows will more heavily scatter the laser light incident thereon. 
         [0017]    According to a fourth aspect of the present invention (invention described in Claim  4 ) is characterized in that, in the above-described second aspect of the invention, the individual vertical hill sections formed on the left side and the individual transverse valley sections formed on the top side are respectively joined at one set of left top corners, the individual vertical valley sections formed on the left side and the individual transverse hill sections formed on the top side are respectively joint at the other set of left top corners, the individual vertical hill sections formed on the right side and the individual transverse valley sections formed on the top side are respectively joined at one set of right top corners, the individual vertical valley sections formed on the right side and the individual transverse hill sections formed on the top side are respectively joined at the other set of right top corners, the individual vertical hill sections formed on the left side and the individual transverse valley sections formed on the bottom side are respectively joined at one set of left bottom corners, the individual vertical valley sections formed on the left side and the individual transverse hill sections formed on the bottom side are respectively joined at the other set of left bottom corners, the individual vertical hill sections formed on the right side and the individual transverse valley sections formed on the bottom side are respectively joined at one set of right bottom corners, and the individual vertical valley sections formed on the right side and the individual transverse hill sections formed on the bottom side are respectively joined at the other set of right bottom corners. The inner sheet body has first to fourth reinforcing sheet bodies, and each of which has the longitudinal direction thereof aligned in the direction of expansion and retraction, attached to the inner surface thereof. The first reinforcing sheet body covers the one and the other sets of left top corners, the second reinforcing sheet body covers the one and the other sets of right top corners, the third reinforcing sheet body covers the one and the other sets of left bottom corners, and the fourth reinforcing sheet body covers the one and the other sets of right bottom corners. 
         [0018]    According to the fourth aspect of the present invention, since the above-described corner portions are covered respectively with the first, second, third and fourth reinforcing sheet bodies, so that the configuration successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the inner sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. 
         [0019]    According to a fifth aspect of the present invention (invention described in Claim  5 ) is characterized in that, in the above-described fourth aspect of the invention, the inner sheet body has U-shaped slits preliminarily formed therein before being folded to form the valley sections. The outer contour of each protruding flap corresponds to the geometry of the U-shaped slit, and each of the first to fourth reinforcing sheet bodies has a width ranging from the end of the straight slit to the end of the U-shaped slit. 
         [0020]    In the beam guiding bellows for laser cutting machine according to the fifth aspect of the present invention, a portion of the inner sheet body, where the hill sections and the valley sections are formed by folding, and not covered by the first to fourth reinforcing sheet bodies, is a portion where the straight slits and the U-shaped slits are formed. According to the fifth aspect of the present invention, the configuration more successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the inner sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. 
         [0021]    According to a sixth aspect of the present invention (invention described in Claim  6 ), there is provided a method of manufacturing a beam guiding bellows for laser cutting machine, which include a step of producing a bellows-making stacked sheet body by stacking an outer sheet body and an intermediate sheet body and the inner sheet body so as to integrate them; and a step of folding the bellows-making stacked sheet body so as to alternately form hill sections and valley sections. The inner sheet body has formed therein U-shaped slits which are configured to automatically form, when folded to form valley sections therealong, protruding flaps so as to project them out from the apexes of the valley sections. 
         [0022]    According to a seventh aspect of the present invention (invention described in Claim  7 ) is characterized in that, in the above-described sixth aspect of the invention, the inner sheet body has formed therein straight slits arranged in the longitudinal direction of the U-shaped slits, while keeping a predetermined distance in between, and the bellows-making stacked sheet body is folded so as to form the valley sections along the U-shaped slits and to form the hill sections along the straight slits. 
         [0023]    According to the method of manufacturing a beam guiding bellows for laser cutting machine described in the sixth and seventh aspects of the present invention, the beam guiding bellows for laser cutting machine described in the first to fifth aspects of the present invention may be manufactured. 
       EFFECT OF THE INVENTION 
       [0024]    In the beam guiding bellows according to the first aspect of the present invention (invention described in Claim  1 ), since the inner sheet body is composed of a material capable of protecting the inner sheet body by absorbing or reflecting the laser light having been scattered or reversed, or has, formed on the inner surface thereof, a protective layer composed of a material capable of protecting the inner layer by absorbing or reflecting the laser light having been scattered, so that the beam guiding bellows may effectively be prevented from being burnt or damaged, even if the inner sheet body was irradiated by the laser light after being scattered on dust adhered on the condenser lens or the reflective mirror, or after being reversed by reflection on a work typically composed of a metal. Also since the beam guiding bellows has protruding flaps which are formed so as to project further inwardly from the apexes of the valley sections, so that the reversed laser light incident on any of the protruding flaps will no longer irradiate the inner sheet body and the protruding flaps which fall behind (closer to the oscillator than) the irradiated protruding flap. Accordingly, by virtue of the inwardly projected arrangement of the protruding flaps inside the beam guiding bellows, a risk of burning or other damages is more effectively avoidable. 
         [0025]    Moreover, the protruding flaps possibly irradiated by the scattered or reversed laser light may be formed (projected) automatically in the process of folding the inner sheet body together with the other sheet bodies to thereby form the hill sections and the valley sections alternately, so as to project further inwardly from the apexes of the valley sections, with no need of attaching any special plates such as reflective plates one by one on the inner surface of the main bellows component already shaped or before being shaped, such as done in the process of manufacturing, the conventional beam guiding bellows. The bellows may therefore be manufactured within a very short time at low costs. In other words, the beam guiding bellows may be finished at the end of manufacturing of the main bellows component which composes the conventional beam guiding bellows, without needing any succeeding process of, for example, attaching the plates such as the reflective plates. This not only contributes to reduce the number of components and weight as a consequence, but also largely shorten the time of manufacturing. 
         [0026]    In the beam guiding bellows according to the second aspect of the present invention (invention described in Claim  2 ), similarly to the first aspect of the invention described in the above, not only the main bellows component may successfully be protected and prevented from being burnt or damaged even if the scattered or reversed laser light is incident on the inner surface thereof, but also the process of arranging the reflective plates will be no more necessary, allowing manufacturing within a short time at low costs. 
         [0027]    In the beam guiding bellows according to the third aspect of the present invention (invention described in Claim  3 ), since the straight slits having shorter length than the overall length of the hill sections, or the overall length of the vertical hill sections and the transverse hill sections, are formed in the portions corresponded to the apexes of the hill sections, or apexes of the vertical hill sections and the transverse hill sections, so that the configuration successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the inner sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. The third aspect of the present invention is particularly effective in avoiding the risk of burning or damage of the beam guiding bellows, for the case where the inner sheet body is composed of a simple species of metal such as aluminum foil, since this sort of inner sheet body is causative of heavier (metal) fatigue under repetitive folding in the process of expansion and retraction, so that the dust which floats inside the beam guiding bellows will more heavily scatter the laser light incident thereon. 
         [0028]    In the beam guiding bellows according to the fourth aspect of the present invention (invention described in Claim  4 ), since the above-described corner portions are covered respectively with the first, second, third and fourth reinforcing sheet bodies, so that the configuration successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the-inner-sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. 
         [0029]    In the beam guiding bellows according to the fifth aspect of the present invention (invention described in Claim  5 ), a portion of the inner sheet body, where the hill sections and the valley sections are formed by folding, and not covered by the first to fourth reinforcing sheet bodies, is a portion where the straight slits and the U-shaped slits are formed. According to the fifth aspect of the present invention, the configuration more successfully avoids the risk of burning or damage of the beam guiding bellows, due to the laser light possibly scattered by dust which floats inside the bellows, after released from the inner sheet body as a result fatigue thereof or partial rupture or separation thereof, under repetitive folding in the process of expansion and retraction. 
         [0030]    According to the method of manufacturing a beam guiding bellows. for laser cutting machine described in the sixth and seventh aspects of the present invention (inventions described in Claims  6  and  7 ), the beam guiding bellows for laser cutting machine described in the first to fifth aspects of the present invention may be manufactured. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a perspective view, partially broken away, illustrating a beam guiding bellows for laser cutting machine according to an embodiment of the present invention; 
           [0032]      FIG. 2  is a perspective view, partially broken away, illustrating the beam guiding bellows for laser cutting machine illustrated in  FIG. 1 ; 
           [0033]      FIG. 3  is a front elevation illustrating the beam guiding bellows for laser cutting machine illustrated in  FIG. 1 ; 
           [0034]      FIG. 4  is a cross-sectional view of the beam guiding bellows for laser cutting machine illustrated in  FIG. 3 , taken along the line A-A; 
           [0035]      FIG. 5  is a cross-sectional view of the beam guiding bellows for laser cutting machine illustrated in  FIG. 3 , taken along the line B-B; 
           [0036]      FIG. 6  is a left side elevation illustrating the beam guiding bellows for laser cutting machine illustrated in  FIG. 3 ; 
           [0037]      FIG. 7  is a right side elevation illustrating the beam guiding bellows for laser cutting machine illustrated in  FIG. 3 ; 
           [0038]      FIG. 8  is perspective view, partially broken away, illustrating the beam guiding bellows for laser cutting machine illustrated in  FIG. 1 ; and 
           [0039]      FIG. 9  is a plan view, partially broken away, illustrating a bellows-making stacked sheet body. 
       
    
    
     EXPLANATION OF THE MARKS 
       [0000]    
       
           1  beam guiding bellows for laser cutting machine 
           2  bellows-making stacked sheet body 
           2   a  left vertical hill sections 
           2   b  left vertical valley sections 
           2   c  right vertical hill sections 
           2   d  right vertical valley sections 
           2   e  upper transverse hill sections 
           2   f  upper transverse valley sections 
           2   g  lower transverse hill sections 
           2   h  lower transverse valley sections 
           6  fourth sheet body 
           6   a  left protruding flap 
           6   b  right protruding flap 
           6   c  upper protruding flap 
           6   d  lower protruding flap 
           6   e  (U-shaped) left slit 
           6   f  (U-shaped) right slit 
           6   g  (U-shaped) upper slit 
           6   h  (U-shaped) lower slit 
           6   s  left straight slit 
           6   t  lower straight slit 
           6   u  right straight slit 
           6   v  upper straight slit 
           8  first reinforcing sheet body 
           9  second reinforcing sheet body 
           10  third reinforcing sheet body 
       
     
       DETAILED DESCRIPTION 
       [0066]    The beam guiding bellows for laser cutting machine, according to best embodiments for carrying out the present invention will be detailed below, referring to the attached drawings. 
         [0067]    A beam guiding bellows for laser cutting machine according to this embodiment (simply referred to as beam guiding bellows, hereinafter)  1  is configured, as illustrated in  FIG. 1 , by folding a bellows-making stacked sheet body  2  into a square cylindrical form. The beam guiding bellows  1  is disposed so as to cover an optical path of laser light emitted from an oscillator owned by an unillustrated laser cutting machine. In the individual drawings, the oscillator is disposed in the direction indicated by arrow A, and the optical path extends therefrom in the direction indicated by arrow B, towards a reflective mirror or a condenser lens. The description below will be given, assuming the portions located closer to the direction A as the front side, and those located closer to the direction B as the rear side. 
         [0068]    The bellows-making stacked sheet body  2  is, as illustrated in  FIG. 1 , composed of a first sheet body  3  which composes the outermost cloth of the beam guiding bellows  1 , a second sheet body  4  which is disposed as an interlining behind the first sheet body  3 , a third sheet body  5  which binds the second sheet body  4  and a fourth sheet body  6  which will be described in the next to each other, the fourth sheet body  6  attached to the third sheet body  5 , and first to fourth reinforcing sheet bodies (reference numerals not given) which will be explained later in relation to a method of manufacturing of the beam guiding bellows. Note that  FIG. 1  shows the appearance of the beam guiding bellows  1 , while partially braking the second sheet body  4 , the third sheet body  5  and the fourth sheet body  6 , for better understanding of the configuration of the bellows-making stacked sheet body  2 . The first sheet body  3  is the outer sheet body which configures the present invention, or the outermost cloth of the beam guiding bellows  1 , and is configured in this embodiment by a sheet composed of synthetic leather. The first sheet body  3  has an unillustrated adhesive (or pressure-sensitive adhesive) coated on the inner surface (back surface) thereof. The second sheet body  4  is the intermediate sheet body which configures the present invention, or an interlining which ensures shape retention of the beam guiding bellows  1 , and is composed of a material slightly more rigid than the first sheet body  3 . The second sheet body  4  is specifically composed of polyethylene terephthalate (PET) or the like, and has straight slits formed periodically at the portions where the hill sections and the valley sections will be formed when the bellows-making stacked sheet body  2  is folded, as described later. In the beam guiding bellows  1  of this embodiment, the second sheet body  4  is divided into four parts. A specific configuration of the second sheet body  4  will be described later in relation to the method of manufacturing the beam guiding bellows. The fourth sheet body  6  is the inner sheet body which configures the present invention, specifically configured by a film-like base typically composed of polyethylene terephthalate (PET) and an alumite layer (protective layer) formed on the inner surface or the outer surface thereof, and has two types of slits (U-shaped slits and straight slits) formed therein, as described later. In the beam guiding bellows  1  of this embodiment, the fourth sheet body  6  is divided into four parts. The third sheet body  5  is used for bonding the second sheet body  4  and the fourth sheet body  6 , and has an adhesive (or pressure-sensitive adhesive) coated on both surfaces. In the beam guiding bellows  1  of this embodiment, also the third sheet body  5  is divided into four parts, corresponding to the number of division of the fourth sheet body  6 . Also the configuration of the third sheet body  5  and the fourth sheet body  6  will be detailed later. Accordingly, the first sheet body  3  and the second sheet body  4  are bonded via an adhesive (or pressure-sensitive adhesive) coated on the inner surface of the first sheet body  3 , and the second sheet body  4  and the fourth sheet body  6  are bonded via the third sheet body  5 . The bellows-making stacked sheet body  2  is thus configured by integrally stacking the first to fourth sheet bodies  3  to  6 . The first to fourth reinforcing sheet bodies will be explained later. 
         [0069]    The bellows-making stacked sheet body  2 , having the first to fourth sheet bodies  3  to  6  (and the first to fourth reinforcing sheet bodies) integrated therein, is folded so as to alternately form hill sections and valley sections (reference numerals not given), as illustrated in  FIG. 1 . The hill sections and valley sections will further be detailed. As illustrated in  FIG. 2 , FIG,  3 ,  FIG. 4  or  FIG. 5 , in the left portion of the beam guiding bellows  1 , there are formed left vertical hill sections  2   a  with the longitudinal direction thereof vertically aligned, and left vertical valley sections  2   b  formed alternately in between, whereas in the right portion of the beam guiding bellows  1 , there are formed right vertical hill sections  2   c  with the longitudinal direction thereof vertically aligned, and right vertical valley sections.  2   d  formed alternately in between (see  FIG. 5 ). In the top portion of the beam guiding bellows  1 , there are formed upper transverse hill sections  2   e  with the longitudinal direction laterally aligned, and upper transverse valley sections  2   f  formed alternately in between, whereas in the bottom portion of the beam guiding bellows  1 , there are formed lower transverse hill sections  2   g  with the longitudinal direction thereof laterally aligned, and lower transverse valley sections  2   h  formed alternately in between (see  FIG. 4 ). The individual top ends of the left vertical hill sections  2   a  are joined, as illustrated in  FIG. 6 , with the individual upper transverse valley sections  2   f  at a corner portion (the one set of left top corners composing the present invention: a reference numeral not given), whereas the individual bottom ends are joined with the individual lower transverse valley sections  2   h  at a corner portion (the one set of left bottom corners composing the present invention: a reference numeral not given). On the other hand, the individual top ends of the left vertical valley sections  2   b  are joined with the individual upper transverse hill sections  2   e  at a corner portion (the other set of left top corners composing the present invention: a reference numeral not given), whereas the individual bottom ends are joined with the individual lower transverse hill sections  2   g  at a corner portion(the other set of left bottom corners composing the present invention: a reference numeral not given). Similarly, the individual top ends of the right vertical hill sections  2   c  are joined, as illustrated in  FIG. 7 , with the individual upper transverse valley sections  2   f  at a corner portion (the one set of right top corners composing the present invention: a reference numeral not given), whereas the individual bottom ends are joined with the individual lower transverse valley sections  2   h  at a corner portion (the one set of right bottom corners composing the present invention: a reference numeral not given). The individual top ends of the right vertical valley sections  2   d  are joined with the individual upper transverse hill sections  2   e  at a corner portion (the other set of right top corners composing the present invention: a reference numeral not given), and the individual bottom ends are joined with the individual lower transverse hill sections  2   g  at a corner portion (the other set of right bottom corners composing the present invention: a reference numeral not given). 
         [0070]    The left end of every upper transverse hill section  2   e  and the left end of every upper transverse valley section  2   f  located ahead (in the direction indicated by arrow A) of the upper transverse hill section  2   e  are connected by one set of left upper slopes  2   j  as illustrated in  FIG. 6 , whereas the left end of every upper transverse hill section  2   e  and the left end of every upper transverse valley section  2   f  located behind (in the direction indicated by arrow B) the upper transverse hill section  2   e  are connected by the other set of left upper slopes  2   k.  The left end of every lower transverse hill section  2   g  and the left end of every lower transverse valley sections  2   h  located ahead (in the direction indicated by arrow A) of the lower transverse hill section  2   g  are connected by one set of left lower slopes  2   l , whereas the left end of every lower transverse hill section  2   g  and the left end of every lower transverse valley section  2   h  located behind (in the direction indicated by arrow B) the lower transverse hill section  2   g  are connected by the other set of left lower slopes  2   m.  The right end of every upper transverse hill section  2   e  and the right end of every upper transverse valley section  2   f  located ahead (in the direction indicated by arrow A) of the upper transverse hill section  2   e  are connected, as illustrated in  FIG. 7 , by one set of right upper slopes  2   n , whereas the right end of every upper transverse hill section  2   e  and the right end of every upper transverse valley section  2   f  located behind (in the direction indicated by arrow B) the upper transverse hill section.  2   e  are connected by the other set of right upper slopes  2   o . The right end of every lower transverse hill section  2   g  and the right end of every lower transverse valley section  2   h  located ahead (in the direction indicated by arrow A) of the lower transverse hill section  2   g  are connected by one set of right lower slopes  2   p,  whereas the left end of every lower transverse hill section  2   g  and the right end of every lower transverse valley section  2   h  located behind (in the direction indicated by arrow B) the lower transverse hill sections  2   g  are connected by the other set of right lower slopes  2   q.  Accordingly, the beam guiding bellows  1  of this embodiment may expand or retract when the left vertical hill sections  2   a,  the left vertical valley sections  2   b,  the right vertical hill sections  2   c,  the right vertical valley sections  2   d,  the upper transverse hill sections  2   e,  the upper transverse valley sections  2   f,  the lower transverse hill sections  2   g,  the lower transverse valley sections  2   h , one set of left upper slopes  2   j,  the other set of left upper slopes  2   k,  one set of left lower slopes  2   l , the other set of left lower slopes  2   m,  one set of right upper slopes  2   n,  the other sets of right upper slopes  2   o,  one set of right lower slopes  2   p,  and the other set of right lower slopes  2   q  vary. 
         [0071]    Inside the beam guiding bellows  1 , the protruding flaps configuring the present invention are formed. As illustrated in  FIG. 1 ,  FIG. 2  or  FIG. 3 , the protruding flaps are specifically configured by a plurality of left protruding flaps  6   a,  a plurality of right protruding flaps  6   b,  a plurality of upper protruding flaps  6   c,  and a plurality of lower protruding flaps  6   d.  Each of the left protruding flaps  6   a,  the right protruding flaps  6   b,  the upper protruding flaps  6   c  and the lower protruding flaps  6   d  is a part of the fourth sheet body  6  as the inner sheet body which configures the present invention. Each left protruding flap  6   a  protrudes out from an inner portion (apex) of each left vertical valley section  2   b  inside the beam guiding bellows  1 , and has a length shorter than the overall length of the left vertical valley section  2   b  as illustrated in  FIG. 3  or  FIG. 4 . Each right protruding flap  6   b  protrudes out from an inner portion (apex) of each left vertical valley section  2   d  inside the beam guiding bellows  1 , and has a length shorter than the overall length of the left vertical valley section  2   d.  Each upper protruding flap  6   c  protrudes out from an inner portion (apex) of each upper transverse valley section  2   f  inside the beam guiding bellows  1 , and has a length shorter than the overall length of the upper transverse valley section  2   f.  Each lower protruding flap  6   d  protrudes out from an inner portion (apex) of each lower transverse valley section  2   h  inside the beam guiding bellows  1 , and has a length shorter than the overall length of the lower transverse valley section  2   h.  In the fourth sheet body  6 , and in the neighboring portions behind the left protruding flaps  6   a  (on the rear side of the beam guiding bellows  1 , or, in the direction indicated by arrow B), there are formed left slits  6   e  which have a U-shaped geometry corresponding to the outer contour of the left protruding flaps  6   a  (see  FIG. 4 ). In the fourth sheet body  6 , and in the neighboring portions behind the right protruding flaps  6   b  (on the rear side of the beam guiding bellows  1 ), there are formed left slit  6   f  which have a nearly U-shaped geometry corresponding to the outer contour of the left protruding flaps  6   b  (see  FIG. 8 ). In the fourth sheet body  6 , and in the neighboring portions behind the right protruding flaps  6   c  (on the rear side of the beam guiding bellows  1 ), there are formed left slit  6   g  which have a nearly U-shaped geometry corresponding to the outer contour of the left protruding flaps  6   c  (see  FIG. 8 ). In the fourth sheet body  6 , and in the neighboring portions behind the right protruding flaps  6   d  (on the rear side of the beam guiding bellows  1 ), there are formed left slit  6   h  which have a nearly U-shaped geometry corresponding to the outer contour of the left protruding flaps  6   d  (see  FIG. 5 ,  FIG. 1  or  FIG. 8 ). 
         [0072]    In the fourth sheet body . 6  (the inner sheet body composing the present invention), left straight slits are formed in the portions corresponded to the individual left vertical hill sections  2   a,  right straight slits are formed in the portions corresponded to the individual right vertical hill sections  2   c,  upper straight slits are formed in the portions corresponded to the individual upper transverse hill sections  2   e,  and lower straight slits are formed in the portions corresponded to the individual lower transverse hill sections  2   g.  The left straight slits, the right straight slits, the upper straight slits and the lower straight slits will be explained below in relation to a method of manufacturing the beam guiding bellows  1 . 
         [0073]    Now the above-mentioned method of manufacturing the beam guiding bellows  1  will be explained step by step. In advance of the explanation, configuration of the first to fourth sheet bodies  3  to  6  will be described.  FIG. 9  is plan view, partially broken away, illustrating the bellows-making stacked sheet body  2  configured by stacking the first to fourth sheet bodies  3  to  6 , and the above-mentioned first to fourth reinforcing sheet bodies  8 ,  9  and  10  (the fourth reinforcing sheet body not illustrated). The first sheet body  3  is the outermost cloth of the beam guiding bellows  1 , or the outer sheet body configuring the present invention, as described in the above. The first sheet body  3  is composed of a synthetic leather, has a rectangular geometry, and has a margin  3   a  for gluing on the right side thereof, which is left for gluing for shaping of the folded bellows-making stacked sheet body  2  into a cylinder by overlapping with the first sheet body  3 . 
         [0074]    What is placed on the first sheet body  3  (on the back surface of the first sheet body  3  in the finished form of the beam guiding bellows  1 ) is the second sheet body  4 , or the intermediate sheet body configuring the present invention. The second sheet body  4  is divided into four parts, in the beam guiding bellows  1  of this embodiment, More specifically, as seen in  FIG. 9 , the second sheet body  4  is composed of a left interlining  41  disposed leftmost, a lower interlining  42  disposed alongside of the left interlining  41  while keeping a small gap in between, a right interlining  43  disposed alongside of the lower interlining  42  while keeping a small gap in between, and an upper interlining  44  disposed rightmost and alongside of the right interlining  43  while keeping a small gap in between. The left interlining  41  is located in the left portion of the beam guiding bellows  1  illustrated in  FIG. 1 , the lower interlining  42  is located on the bottom portion of the beam guiding bellows  1 , the right interlining  43  is located in the right portion of the beam guiding bellows  1 , and the upper interlining  44  is located in the top portion of the beam guiding bellows  1 . In the left interlining  41 , slits (perforations)  41   a  are formed side-by-side (in the longitudinal direction of the left interlining  41 ) corresponding to portions where the left vertical hill sections  2   a  will be formed as a result of folding. Between the adjacent slits (perforations)  41   a,  the slits (perforations)  41   b  are formed corresponding to portions where the left vertical valley sections  2   b  will be formed. In the lower interlining  42 , slits (perforations)  42   a  are formed side-by-side (in the longitudinal direction of the lower interlining  42 ) corresponding to portions where the lower transverse valley sections  2   h  will be formed as a result of folding. Between the adjacent slits (perforations)  42   a,  slits (perforations)  42   b  are formed corresponding to portions where the lower transverse hill sections  2   g  will be formed. In the right interlining  43 , slits (perforations)  43   a  are formed side-by-side (in the longitudinal direction of the right interlining  43 ) corresponding to portions where the right vertical hill sections  2   c  will be formed as a result of folding. Between the adjacent slits (perforations)  43   a,  slits (perforations)  43   b  are formed corresponding to portions where the right vertical valley sections  2   d  will be formed. In the upper interlining  44 , slits (perforations)  44   a  are formed side-by-side (in the longitudinal direction of the upper interlining  44 ) corresponding to portions where the upper transverse valley sections  2   f  will be formed as a result of folding. Between the adjacent slits (perforations)  44   a , slits (perforations)  44   b  are formed corresponding to portions where the upper transverse hill sections  2   e  will be formed as a result of folding. On the left edge of the left interlining  41  and on the right edge of the upper interlining  44 , there are formed inclined edges  41   c,    41   d ,  44   c  and  44   d  which correspond to the one set of left upper slopes  2   j  and the other set of left upper slopes  2   k.  On the right edge of the left interlining  41  and on the left edge of the lower interlining  42 , there are formed inclined edges  41   e,    41   f,    42   c  and  42   d  which correspond to the one set of left lower slopes  2   l  and the other set of left lower slopes  2   m.  On the right edge of the lower interlining  42  and on the left edge of the right interlining  43 , there are formed inclined edges  42   e,    42   f,    43   c  and  43   d  which correspond to the one set of right lower slopes  2   p  and the other set of right lower slopes  2   q.  On the right edge of the right interlining  43  and on the left edge of the upper interlining  44 , there are formed inclined edges  43   e,    43   f ,  44   e  and  44   f  which correspond to the one set of right upper slopes  2   n  and the other set of right upper slopes  2   o.    
         [0075]    A left adhesive sheet body  51  is adhered to the left interlining  41  (which corresponds to the second sheet body  4 ), a lower adhesive sheet body  52  is adhered to the lower interlining  42 , a right adhesive sheet body  53  is adhered to the right interlining  43 , and an upper adhesive sheet body  54  is adhered to the upper interlining  44 . The left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53 , and the upper adhesive sheet body  54  configure the third sheet body  5 . In other words, the third sheet body  5  is divided into four parts. The left adhesive sheet body  51 , the lower adhesive sheet body  52 ; the right adhesive sheet body  53 , and the upper adhesive sheet body  54  are coated with an adhesive on both surfaces thereof, have lengths equal to those of the left interlining  41 , the lower interlining  42 , the right interlining  43 , and the upper interlining  44 , respectively, and have widths equal to the width of the slits (perforations)  41   a,    42   b,    43   a  and  44   b,  respectively. Moreover, each of the left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53 , and the upper adhesive sheet body  54  has oblong holes  51   a,    52   a,    53   a  and  54   a  respectively formed therein, while being aligned in the longitudinal direction of each sheet body. The oblong holes  51   a,    52   a,    53   a  and  54   a  are formed at positions so as to allow them to be halved at the centers thereof by the slits (perforations)  41   a,    41   b,    42   a,    42   b ,  43   a,    43   b,    44   a  and  44   b,  with the length thereof slightly shorter than the width of the adhesive sheet bodies  51  and so forth. More specifically, the length of the oblong holes  51   a  formed in the left adhesive sheet body  51  is slightly shorter than the lengths of the left vertical hill sections  2   a  and the left vertical valley sections  2   b  in the final form of the beam guiding bellows  1  after being folded as described later, and the length of the oblong holes  52   a  formed in the lower adhesive sheet body  52  is slightly shorter than the lengths of the lower transverse hill sections  2   g  and the lower transverse valley sections  2   h  in the final form of the beam guiding bellows  1  after being folded as described later. Similarly, the length of the oblong holes  53   a  formed in the right adhesive sheet body  53  is slightly shorter than the lengths of the right vertical hill sections  2   c  and the right vertical valley sections  2   d  in the final form of the beam guiding bellows  1  after being folded as described later, and the length of the oblong holes  54   a  formed in the upper adhesive sheet body  54  is slightly shorter than the lengths of the upper transverse hill sections  2   e  and the upper transverse valley sections  2   f  in the final form of the beam guiding bellows  1  after being folded as described later. 
         [0076]    On the left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53  and the upper adhesive sheet body  54 , there are formed a left protective sheet body  61 , a lower protective sheet body  62 , a right protective sheet body  63 , and an upper protective sheet body  64 . The left protective sheet body  61 , the lower protective sheet body  62 , the right protective sheet body  63 , and the upper protective sheet body  64  configure the fourth sheet body  6 . In other words, the above-described fourth sheet body  4 , which configures the bellows-making stacked sheet body  2  to be formed into the beam guiding bellows  1 , is divided into four parts. The above-described plurality of the left slits  6   e  are formed in the left protective sheet body  61 , the plurality of lower slits  6   h  are formed in the lower protective sheet body  62 , the plurality of right slits  6   f  are formed in the right protective sheet body  63 , and the plurality of upper slits  6   g  are formed in the upper protective sheet body  64 . Each of the left slits  6   e,  the lower slits  6   h,  the right slits  6   f,  and the upper slits  6   g  is a slit formed to have a U-shape as described in the above. Accordingly, in the left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53 , and in the upper adhesive sheet body  54 , the plurality of left protruding flaps  6   a , the plurality of lower protruding flaps  6   d,  the plurality of right protruding flaps  6   b,  and the plurality of upper protruding flaps  6   c  are formed by the left slits  6   e,  the lower slits  6   h,  the right slits  6   f,  and the upper slit  6   g , respectively. Moreover, in the left protective sheet body  61 , the lower protective sheet body  62 , the right protective sheet body  63 , and in the upper protective sheet body  64 , left straight slits  6   s  are formed between every adjacent left slits  6   e,  lower straight slits  6   t  are formed between every adjacent lower slits  6   h,  right straight slits  6   u  are formed between every adjacent right slits  6   f,  and upper straight slits  6   v  are formed between every adjacent upper slits  6   g.  All of the left protruding flaps  6   a,  the lower protruding flaps  6   d,  the right protruding flaps  6   b , the upper protruding flaps  6   c,  the left straight slits  6   s , the lower straight slits  6   t,  the right straight slits  6   u , and the upper straight slits  6   v  are positioned so as to fall within the oblong holes  51   a,    52   a,    53   a  and  54   a  formed in the left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53 , and in the upper adhesive sheet body  54 , and are thereby set free without being adhered to anything. Both lateral sides of the left protective sheet body  61 , the lower protective sheet body  62 , the right protective sheet body  63 , and the upper protective sheet body  64  have a scallop profile (reference numerals not given) for the convenience of alignment when they are placed on the left adhesive sheet body  51 , the lower adhesive sheet body  52 , the right adhesive sheet body  53 , and the upper adhesive sheet body  54 . 
         [0077]    On the topmost surface of the bellows-making stacked sheet body  2  (on the innermost surface in the finished form of the beam guiding bellows  1 ), the first to fourth reinforcing sheet bodies  8 ,  9  and  10  (the fourth reinforcing sheet body is not illustrated) are adhered (bonded) using an adhesive. All of the first to fourth reinforcing sheet bodies  8 ,  9 ,  10  and  11  (the fourth reinforcing sheet body is not illustrated in  FIG. 9 , since it is bonded after the bellows-making stacked sheet body  2  is folded and shaped into a cylinder by bonding on the margin  3   a  for gluing. See  FIG. 2  to  FIG. 4 ) are ribbon-like component made of a flame-retardant material, and have a length equal to the width of the first sheet body  3 . The first reinforcing sheet body  8  is attached to a position which falls between the left slits  6   e  and the lower straight slits  6   t,  and between the left straight slits  6   s  and the lower slits  6   h;  the second reinforcing sheet body  9  is attached to a position which falls between the lower slits  6   h  and the right straight slits  6   u,  and between the lower straight slits  6   t  and the right slits  6   f;  the third reinforcing sheet body  10  is attached to a position which falls between the right slits  6   f  and the upper straight slits  6   v,  and between the right straight slits  6   u  and the upper slits  6   g.  In short, the first to fourth reinforcing sheet body  8 ,  9 ,  10  and  11  have a width which falls in the distance between the adjacent slits. The fourth reinforcing sheet body is attached to a position which falls between the oblong holes  54   a  and  51   a.  Accordingly, the first to fourth reinforcing sheet bodies  8 ,  9 ,  10  and  11  cover the individual corner portions (the one and the other sets of left top corners, the one and the other sets of left bottom corners, the one and the other sets of right bottom corners, and the one and the other sets of right top corners, which configure the present invention); and also cover the one and the other sets of left upper slopes  2   j  and  2   k,  the one and the other sets of left lower slopes  2   l  and  2   m,  the one and the other sets of right lower slopes  2   p  and  2   q,  and the one and the other sets of right upper slopes  2   n  and  2   o.    
         [0078]    The thus-configured, bellows-making stacked sheet body  2  is then folded at the positions where the individual slits (perforations)  41   a,    41   b,    42   a,    42   b,    43   a,    43   b,    44   a  and  44   b  of the left interlining  41 , the lower interlining  42 , the right interlining  43 , and the upper interlining  44 , so as to form the left vertical hill sections  2   a,  the left vertical valley sections  2   b,  the right vertical hill sections  2   c,  the right vertical valley sections  2   d,  the upper transverse hill sections  2   e,  the upper transverse valley sections  2   f,  the lower transverse hill sections  2   g , and the lower transverse valley sections  2   h,  and also so as to form the one set of left upper slopes  2   j,  the other set of left upper slopes  2   k,  the one set of left lower slopes  2   l , the other set of left lower slopes  2   m,  the one set of right upper slopes  2   n,  the other set of right upper slopes  2   o,  the one set of right lower slopes  2   p,  and the other set of right lower slopes  2   q  (folding step). In this process, the individual left protruding flaps  6   a,  the lower protruding flaps  6   d,  the right protruding flaps  6   b,  and the upper protruding flaps  6   c  automatically rise up in the vicinity of the individual left straight slits  6   s,  the lower straight slits  6   t,  the right straight slits  6   u,  and the upper straight slits  6   v,  so as to extend from the left vertical valley sections  2   b,  the right vertical valley sections  2   d,  the upper transverse valley sections  2   f,  and the lower transverse valley sections  2   h,  respectively. After completion of the folding step, the margin  3   a  for gluing is attached to the exterior of the first sheet body  3  so as to shape the folded bellows-making stacked sheet body  2  into a cylinder, and thereafter the fourth reinforcing sheet body is attached to the interior. 
         [0079]    According to the beam guiding bellows  1  manufactured by the method described in the above, even if the fourth sheet body  6  (left protective sheet body  61 , lower protective sheet body  62 , right protective sheet body  63 , upper protective sheet body  64 ) which composes the inner sheet body is irradiated by scattered or reversed laser light, the beam guiding bellows  1  may successfully avoid the risk of being burnt or damaged, through absorption or reflection of the laser light. In addition, in the beam guiding bellows  1 , the laser light incident on any of the left protruding flaps  6   a,  the lower protruding flaps  6   d , the right protruding flaps  6   b,  and the upper protruding flaps  6   c,  which are formed as the protruding flaps configuring the present invention using the fourth sheet body  6  (left protective sheet body  61 , lower protective sheet body  62 , right protective sheet body  63 , upper protective sheet body  64 ), will no longer irradiate the fourth sheet body  6  including the protruding flaps which fall behind (in the direction opposite to the oscillator than) the irradiated protruding flaps. Accordingly, by virtue of the inwardly projected arrangement of the protruding flaps  6   a  and so forth inside the beam guiding bellows, the risk of burning or other damages is more effectively avoidable. 
         [0080]    In addition, the left protruding flaps  6   a,  the lower protruding flaps  6   d,  the right protruding flaps  6   b,  and the upper protruding flaps  6   c  which configure the protruding flaps are formed (projected) automatically in the process folding the inner sheet body  2  as described in the above, so that the bellows may be manufactured within a very short time at low costs, and may further ensure reduction in the number of components and reduction in weight as a consequence. 
         [0081]    In particular, in the beam guiding bellows  1  of the above-described embodiment, since the left straight slits  6   s,  the lower straight slits  6   t,  the right straight slits  6   u,  and the upper straight slits  6   v  are respectively formed in the left protective sheet body  61 , the lower protective sheet body  62 , the right protective sheet body  63 , and in the upper protective sheet body  64 , in the portions corresponded to the left vertical hill sections  2   a,  the right vertical hill sections  2   c,  the upper transverse hill sections  2   e,  and the lower transverse hill sections  2   g,  so that the protective sheet bodies  61  and so forth may be prevented from being released due to rupture or separation possibly caused by repetitive expansion and retraction of the beam guiding bellows  1 . Since the individual corner portions (the one and the other sets of left top corners, the one and the other sets of left bottom corners, the one and the other sets of right bottom corners, and the one and the other sets of right top corners configuring the present invention), and also the one and the other sets of left upper slopes  2   j  and  2   k,  the one and the other sets of left lower slopes  2   l  and  2   m,  the one and the other sets of right lower slopes  2   p  and  2   q,  and the one and the other sets of right upper slopes  2   n  and  2   o  are covered with the first to fourth reinforcing sheet bodies  8 ,  9 ,  10  and  11  so that the protective sheet bodies  61  and so forth may more effectively be prevented from being released due to rupture or separation possibly caused by repetitive folding. 
         [0082]    While the exemplary case described in the above, referring to the attached drawings in relation to the embodiment of the beam guiding bellows  1 , was such that the third sheet body  6 , or the inner sheet body configuring the present invention, was divided into four parts which include the left protective sheet body  61 , the lower protective sheet body  62 , the right protective sheet body  63 , and the upper protective sheet body  64 , the inner sheet body may alternatively be configured by a single sheet body. Also while the beam guiding bellows  1  of this embodiment described in the above had the one set of left upper slopes  2   j,  the other set of left upper slopes  2   k,  the one set of left lower slopes  2   l , the other set of left lower slopes  2   m,  the one set of right upper slopes  2   n,  the other set of right upper slopes  2   o,  the one set of right lower slopes  2   p,  and the other set of right lower slopes  2   q  formed therein, the beam guiding bellows  1  of the present invention may alternatively have none of these slopes formed therein.