Packaging container production equipment and packaging container production method

Abstract: A packaging container production method for forming tubular web from sheet-like web and producing hexahedral packaging containers, wherein in order to secure a prescribed web W feeding amount, the operating amount of lug folding flaps, which forms a sealing part on tubular web by pressing both sides of the tubular web while folding the same, is set an idealistic position, pressure is generated at a cylinder 16 by a control device 23 via a control valve 31, in compliance with the deviation of the detection mark such as a specified printing pattern on the printing surface on web W from the reference position when the same is detected, and the tension applied onto web W is adjusted by the dancer roller 9.

Description: Technical Field The present invention relates to packaging container producing equipment and a packaging container producing method, in particular to packaging container producing equipment and a packaging container producing method of reforming sheet-like web to tubular web and filling said tubular web with contents such as fluid food. Background Art In packaging container producing equipment for producing packaging containers, into which a content is filled, from sheet-like web, rolled sheet-like web W of rewinder 1, which is wound to be roll-like as shown in FIG. 1, is wound back by a windback device, the wound-back sheet-like web W is transferred by web feeding roller 10 and is sent to tube forming device 3 via tension pressing device 2 consisting of a dancer roll (rocking roller) 9, which gives tension to the abovementioned web W at all times, and guide roller 11, wherein the sheet-like web W is reformed to be tubular web W while being formed by forming rollers 14 (only one stage is illustrated in FIG. 1) provided to be multi-staged, and the edges overlapped in the lengthwise direction of the tubular web W are sealed (longitudinally sealed) in the longitudinal direction. Furthermore, after a part of web W is sealed (cross-sealed) in the direction orthogonal to the lengthwise direction of web W, a content is filled into a tubular web W located in the upstream side of the cross-sealed part, and after cross sealing is further carried out at a size equivalent to one container at the abovementioned web, said cross sealed part is cut off, thereby a hexahedral packaging container C is produced, in which the content is filled. The tube forming device 3 is provided with a filling pipe 5 to fill a tube with a content such as fluid food, etc. and is provided with a pair of seal jaws 7 (only one jaw 7 is illustrated in FIG.1, two pairs of cross seal jaws 7 are provided so as to vertically move) in order to seal the tubular web W from both the sides of the tubular web W via a drive mechanism (not illustrated) from the main shaft 6 of the packaging container producing equipment. A pair of cross seal jaws 7 move downwards while pulling downward the tubular web W being transferred. After the seal jaws 7 falls down to an appointed distance, they release the sealing state of web W to cancel the downward transfer force of the tubular web W and move in such a direction of separating each other. Then, the seal jaws 7 are elevated to an appointed distance and repeat a sealing action of the tubular web W again. At this time, as shown in a detailed view (only one of the pair is illustrated in this drawing) of the cross seal jaws 7 of FIG.3, the abovementioned cross seal jaws 7 are provided with jaws 7b attached to a horizontal bar 7a, and web is nipped between a pair of jaws 7b to cause a cross sealing to be executed. Furthermore, lug folding flaps 7c rotating in the direction of the arrow A are attached to one of the cross seal jaws 7, wherein while web W is nipped between a pair of jaws 7b, the abovementioned lug folding flap 7c is able to fold lugs Wb formed at the web W. On the other hand, specified printing patterns and detection marks a (See FIG.6) such as a straw port for registering positions are provided at appointed intervals on the web W. As using the position of the abovementioned detection mark a as reference, it is necessary to adjust the feeding amount of web W (this is called "mark registration") in packaging container producing equipment so that detection marks a of printing surface of every packaging container C come to an appointed position. However, since errors in positioning of patterns and straw port when printing on sheet-like web and changes of the feeding amount of web W due to defective rotations of rollers in the packaging container producing equipment are unavoidable, it is necessary to register the abovementioned marks at all times while the packaging container producing equipment is in operation. If the feeding amount enters such a state where it can not be adjusted by registering the abovementioned marks, there are cases where packaging containers C which are the final formed products can not be formed to their object shape. Since ever, the mark registration is, as shown below, carried out by combination of (1) a method of adjusting the folding amount of web W in its transfer direction and (2) a method of adjusting the degree of tension applied to web W being transferred. (1) Method of adjusting the folding amount of web W in its transfer direction (See FIG. 8) The feeding amount of web W in the transfer direction is classified into the following two stages of action, wherein the first action is to adjust the feeding amount of web W in the transfer direction by a pulling intensity of web W, and the second action is to adjust the folding angle of lug part formed on web W. By combining these methods, the web W is transferred in the web transfer direction. That is, mechanical feeding action of web W in the transfer direction consists of the following two actions shown in FIG. 8. 1 ○ By the sealing part of web W being nipped at both sides by a pair of cross seal jaws 7, the mechanical feeding action is carried out by pulling the web W equivalently to the moving amount of the cross seal jaws 7 in the web transfer direction (See FIG. 8(a)). 2 ○ The shape of web W taken along the line A-A in FIG.8(a) is as shown in FIG. 8(b), and the lug part web Wb (See FIG. 11) is folded, as shown in FIG. 8(c), from both sides of tubular web W in the right angle direction with respect to the cross seal part Wa (See FIG. 11) formed by the abovementioned action 1 ○. The abovementioned actions 1 ○ and 2 ○ are basically for applying cross sealing to tubular web W, folding a lug part formed at the cross sealed part and finally forming a hexahedral body. However, by adjusting the folding angle of the lug folding flaps 7c, it is possible to adjust the feeding amount of web W. An appointed amount of web W is sent in the abovementioned action 1 ○, and the usual feeding action and corrective feeding action of web W, which will be described later, are carried out in the abovementioned action 2 ○. A detector 19 for detection mark a such as a specified printing pattern, straw port, etc. is installed, as shown in FIG. 6, at a specified point established in advance in packaging container producing equipment. Data signals detecting a detection mark a of web W of the abovementioned detector 19 and cam rotation angle signals of an encoder 22 for detecting the rotation angle of the main shaft 6 to which a cross seal jaw drive cam 24 is attached are inputted into a control device 23. The rotation angle of shaft 6 of the cam 24, which is secured at the point when the data signal of the abovementioned detection mark a is read, is regarded as a detection angle of the a deviation between the detection mark a in the abovementioned control device 23, and the detection angle of the abovementioned detection mark a and the reference angle established in advance is obtained, wherein a value responsive to the deviation is outputted, via a solenoid valve 25, to the pneumatic cylinder 26 for adjusting the folding amount of lug folding flaps 7c (FIG.3) of the cross seal jaws 7. As shown in FIG. 7, lug folding cam 27 is able to take positions 1 ○ and 2 ○ in FIG.5 by the pneumatic cylinder 26. Since a roller 28 moves on the cam surface when the lug folding cam 27 is at the position 1 ○, the lug folding flap 7c carries out a corrective action of folding to the position shown in FIG. 9(b), and since the roller 28 moves on the cam surface when the lug folding cam 27 is at the position 2 ○), the lug folding flaps 7c carries out a usual feeding action of folding to the position shown in FIG. 9(a). The lug folding angle of web W of the lug folding flaps 7c is established from a deviation between the detection angle of the detection mark a by the detector 19 and the reference angle established in advance, in such a manner that a usual feeding action which produces a web feeding amount obtained by adding only 0.5mm to the reference feeding amount is employed until a detection value equivalent to the value obtained by adding only 1.5mm to the reference feeding amount is obtained as for the web feeding amount, and as the detection value equivalent to a value obtained by adding only 1.5mm to the reference feeding amount is obtained as for the web feeding amount, a corrective feeding action which produces a web feeding amount obtained by subtracting only 1.0mm from the reference feeding amount is employed. In FIG. 9, FIG. 9(a) is a view explaining a usual feeding action of web W and FIG. 9(b) is another view explaining a corrective feeding amount of web W. In the usual feeding action of web W in FIG. 9(a), web W is fed at the initial set value equivalent to the web feeding amount obtained by adding only 0.5mm to the reference feeding amount (the feeding amount which becomes a reference on design) at a folding angle A° of the lug folding flaps 7c. Web feeding amount in the usual feeding action = Reference feeding amount + 0.5mm. Furthermore, the folding angle of the lug folding flaps 7c is changed to angle B° in the corrective feeding action of web W shown in FIG. 9(b) to secure the feeding amount obtained by subtracting only 1.0mm from the abovementioned reference feeding amount. Web feeding amount in the corrective feeding action = Reference feeding amount - 1.0mm As regards the abovementioned web W feeding amounts [-1.0mm] or [+0.5mm], the detailed figures are used for only making the explanation more understandable. That is, the usual feeding action and corrective feeding action of the invention are not limited to these figures. Conventionally, the feeding control of web W was controlled by only the abovementioned usual feeding action and corrective feeding action of the lug folding flaps 7c. For example, where it is assumed that there is no printing error (no slip of the detection mark a) of web W, and there is nothing abnormal in the feeding amount of the feeding roller 10, guide roller 11, etc., as shown in FIG.10 (a), the folding angle of the lug folding flaps 7c is changed to angle B°, as shown in FIG. 9(b), and the action is changed to a corrective feeding action at the point of time (after the usual feeding action is performed two times) when web W is excessively fed 0.5mm each by the abovementioned usual feeding amount made by the lug folding flaps 7c and web W is excessively fed 1.5mm which is the allowance of slip from the reference feeding amount. Web W, the slip of which became 0.5mm from the reference feeding amount by the corrective feeding action, is caused to enter the usual feeding action again. In a case where there is no slip of the detection mark a such as a printing error of web W and there is nothing abnormal in the feeding amount of feeding roller 10, guide roller 11, etc., the abovementioned corrective feeding amount is carried out once every three feeding actions (See FIG. 10 (a)). However, herein, since web W is excessively fed 0.5mm per usual feeding action if a slip of the detection mark a of web W such as a printing error is, for example, +0.5mm, the slip from the reference feeding amount in total becomes 1.5mm per usual feeding action, wherein the feeding is changed to a corrective feeding action after the usual feeding action is performed once. Therefore, the corrective feeding action is executed once every two feeding actions as shown in FIG. 10(b). If the control device 23 judges that, in the usual feeding action, a slip from the reference feeding amount became 1.5mm, the action is changed to the corrective feeding action. Furthermore, since web W is excessively fed 0.5mm in the usual feeding action if a slip of the detection mark a of web W is, for example, -0.25mm each, the feeding action is separated 0.25mm each from the reference position in one usual feeding action in total, and at the point of time when the slip from the reference feeding amount becomes 1.5mm, the action is changed to a corrective feeding action. Therefore, as shown in FIG. 10(c), the corrective feeding action is executed once every five feeding actions. (2) Method of adjusting the degree of tension applied onto web W being transferred In order to accurately cause web W to move an appointed distance without fail by the method (1) of adjusting the web feeding amount by adjustment of the folding angle by the lug folding flaps 7c, it is necessary to give adequate fixed tension to web W by the tension pressing device 2. For example, if the tension of web W is too intensive, a mechanical slip occurs between web W and its feeding members, thereby causing the movemental amount of web W to be decreased. To the contrary, if the web tension is too weak, the web is slackened to cause the web W to be transferred beyond the necessity. In order to give an adequate tension to web W, tension pressing device 2 is composed of a web W feeding roller 10, a guide roller 11a, a dancer roller 9 disposed therebetween, a pair of rocking arms 12 having the abovementioned dancer roller 12 at its tip end, which causes the dancer roller 12 to rock, a rotation shaft 13 of the rocking arm 12 secured at the base end of the abovementioned pair of rocking arms 12. The abovementioned mark registration is carried out by combination of the method (2) and the abovementioned method (1). As described above, a corrective action of the feeding amount is carried out by the lug folding flaps 7c for a slight change (for example, 1% of the prescribed value) of the feeding amount of web W. However, it is necessary that a change (error) of the feeding amount of web W, for example, the average error of each time for 100 pitches of web feeding action equivalent to one packaging container C is less than an appointed value (for example, ±0.5mm or less) and a change (error) of the feeding amount of web per pitch of the web feeding action equivalent to one packaging container C does not exceed an appointed value (for example ±1.5mm). Furthermore, the more the consumption of roll-like web W becomes, the more frequently occurs a case where a slip of the detection marks a correctable by the abovementioned method (1) of adjusting the folding amount of web in the transfer direction exceeds the permissible range of correction of the mark registration, wherein it becomes impossible to correct the feeding amount of web W. For example, in three pattern examples shown in FIG. 10(a) through FIG. 10(c), if a slip of the detection mark a from the reference feeding amount, such as a printing error of web W, is +1.0mm per pitch of the abovementioned actions, the slip exceeds the allowance range of detection error at once, thereby causing faulty containers C to be produced. In some cases, packaging container producing equipment is unavoidably caused to come to a stop. Furthermore, if a slip of the detection mark a is continuously, for example, -0.5mm or more per pitch, the slip goes beyond the reference feeding amount line (See FIG. 10) equivalent to the reference feeding amount, the correction of the feeding amount of web W becomes impossible. Furthermore, by repeating the usual feeding action and corrective feeding action through adjustment of folding angle by the abovementioned lug folding flaps 7c, there was such a case where packaging containers C of slightly different shape are produced, the roundness of lug part Wb of web W, for example, is too round, or the corner is too keen. As regards packaging containers C formed by the corrective feeding action, since the folding degree of the lug part Wb is weaker than the reference value, there is a possibility of producing faulty packaging containers C, that is, faulty products, in which sufficient welding is not carried out in the welding process with the body portion having a rectangular section, which is carried out in the subsequent process regarding the formation of web W. Furthermore, inconvenient folding wrinkles may be produced at the corner parts when the final hexahedral body is formed. US-A-4081944 describes an example of a prior art packaging container production equipment for forming tubular web from sheet-like web and producing hexahedral packaging containers in accordance with the foregoing description. Thus, prior arts have a problematic point by which it is possible to adjust the feeding amount of web W while continuously running the machine since the range of adjustment of the feeding amount of web W is narrow. Therefore, it is an object of the invention to eliminate the deficits of the prior arts. It is an object of the invention to quickly eliminate an error of detection mark registrations such as a printing error on web W, and to provide packaging containers, free from any unevenness in shape, for which the range of adjustment of the feeding amount of web W can be widened, the adjustment of the feeding amount of web W can be carried out with the machine running, and the formability of which is further improved. Disclosure of the Invention The themes and objects of the invention can be solved by the following construction. Packaging container production equipment for forming tubular web from sheet-like web and producing hexahedral packaging containers, comprises: a web tension pressing means provided with a rocking arm and a rocking roller secured at the tip end thereof, which transfers sheet-like web while pressing the sheet-like web by the rocking roller; a web tension pressing force setting means for setting the pressing force of said tension pressing means; a sealing member for forming sealing parts at tubular web by pressing both sides of the tubular web while folding both the sides of said tubular web, and simultaneously transferring web at an appointed feeding amount; a mark detecting means for detecting that specified detection marks which will be targets on the web are fed onto the points of detection which will be the specified references established in advance; and a web tension pressing force controlling means for escalationally or continuously adjusting the pressing force set value of web tension pressing force setting means to an optimal value in response to the deviation between a timing when said specified mark detecting means detects a specified detection mark on said web at a specified point, and a timing when a specified printing detection mark is detected, which will be a reference established in advance at said specified point of detection. Furthermore, a packaging container production method for forming tubular web from sheet-like web and producing hexahedral packaging containers, comprises the steps of: transferring sheet-like web while controlling a tension pressing force to an optimal value with respect to the sheet-like web; forming tubular web from the sheet-like web being transferred; nipping both the sides of the tubular web in the direction orthogonal to the lengthwise direction said tubular web and forming a sealing part at the tubular web by folding the same, and simultaneously transferring web at an appointed feeding amount; and continuously or escalationally controlling the web tension pressing force so as to become an optimal value in compliance with the deviation between the timing when a specified detection mark on the web is sent to a point of detection which becomes a specified reference established in advance and the timing when a specified detection mark is detected, which will be the reference established in advance at said specified point. With the invention, in the packaging container producing equipment, the operation amount (folding angle etc.) of a sealing member (for example, lug folding flaps), which forms a sealing part at tubular web by pressing both sides of the tubular web while folding the same, is set to an appointed idealistic value in order to secure a prescribed web W feeding amount, thereby causing the tension given to web W being transferred to be controlled. Therefore, in a case where correction is necessary for the web feeding amount, the correction is carried out by controlling the tension operating on the web W while always keeping the operating amount (folding angle) of the sealing member (for example, lug folding flaps) fixed. As a tension pressing force setting means of the invention, an actuator may be used, which is represented by a pneumatic cylinder, a hydraulic cylinder provided with a pressure change unit for generating pressure to press the rocking arm in multistage or an electro-pneumatic proportional valve for stagelessly generating pressure proportionate to a size of electric signals. According to the invention, it is possible to adjust the feeding amount of web W by controlling a pressing force given to web W in the tension pressing device, in compliance with a deviation of a detection mark such as a specified printing pattern on the printing surface of web W from the reference value of detection value. It is preferable that the deviation of the detected value of detection marks such as a printing pattern on the printing surface on web W from the reference values is based on the deviation between the reference set value of the rotating angle or number of times of rotation of the main shaft of the packaging container producing equipment and the detected value of the detection marks. This is because that the drive amount of almost all the drive parts of the packaging container producing equipment such as cross seal jaws, container forming conveyor, etc. depend upon the value of the rotating angle and the number of times of rotations of the main shaft, However, not depending the rotating angle and the number of times of rotations of the main shaft, the deviation of the detected value of the abovementioned specified detection marks from the reference value may be measured on the basis of the drive amount of the other drive parts. With the invention, in addition to the abovementioned construction, the web tension pressing means is provided with a dancer roller rocking in the vertical direction and a web feeding roller having a drive force for sending web W into the transfer direction, and the web tension pressing force controlling means is provided with position detecting means of the upper limit and lower limit positions of a dancer roller rocking in the vertical direction and a construction capable of changing the sheet-like web to a high-speed set value and low-speed set value by the feeding roller by detecting the upper limit and lower limit positions of the dancer roller of each of the abovementioned position detection means, wherein it is possible to further widen the adjustment width of the web feeding amount. Thus, with the invention, the range of correction can be expanded in comparison with the range of correction of the conventional web W feeding amount, and the allowable range for unevenness of detection marks such as a printing error on web W can be also expanded. Therefore, it is possible to perform consecutive operation of the machine without stopping, and it is possible to produce packaging containers in which detection marks such as printing patterns can be correctly placed at appointed positions, thereby causing faulty products not to be produced. Brief Description of the Drawings FIG.1 is a sketch of equipment for producing packaging containers, in which a content is filled, from sheet-like web according to a preferred embodiment of the invention, FIG.2 is a rough perspective view of a tension pressing device of the packaging container producing equipment of FIG. 1, FIG.3 are the cross seal jaw of the packaging container producing equipment of FIG. 1, FIG.3a is a perspective view of cross seal jaw, and FIG. 3b is a top plan view thereof, FIG.4 is a view showing a drive mechanism of flaps, by which the operating amount (feeding amount) of lug folding flaps of packaging container producing equipment of FIG. 1 is kept fixed at all the times, FIG.5 is a block diagram of a control device of tension pressing force of packaging container producing equipment of FIG.1, FIG.6 is a view explaining a mechanism of carrying out mark registration of the cross seal jaw of the conventional packaging container producing equipment, FIG.7 is a view explaining a flap drive section of FIG.6, FIG.8 are the cross seal jaw of packaging container producing equipment of FIG.1, FIG.8a is an operation view of the cross seal jaw and FIG.8b and FIG.8c are perspective views taken along the line A-A in FIG.8a, and FIG.9 are the explaining a usual feeding action of the cross seal jaw of the packaging container producing equipment of prior arts, FIG.9a is a view explaining a usual feeding action of the cross seal jaw and FIG.9b is also a view explaining a corrective feeding action thereof, FIG.10 is a pattern chart of combined movements of the usual feeding action and corrective feeding action in FIG.9, FIG.11 is a perspective view of the cross sealing part of tubular web. Description of the Preferred Embodiments A description is given of a preferred embodiment of the invention. Packaging container producing equipment according to a preferred embodiment of the invention is composed of the same construction as the packaging container producing equipment described in FIG. 1. FIG. 2 is a sketch of a tension pressing device of web W being transferred, which is not illustrated in the packaging container producing equipment of FIG. 1, FIG. 3(a) is an enlarged perspective view of web cross seal jaws 7, and FIG. 3(b) is a top view thereof. FIG. 4 is a view of a drive mechanism of lug folding flaps, which keeps the operating amount (folding angle) of the lug folding flaps 7c fixed. Herein, reference parts of members having the same feature as those of equipment described in the conventional example are given the same reference numbers in the equipment of the invention, and the description thereof is omitted. Packaging container producing equipment according to a preferred embodiment of the invention is as described above, with reference to FIG.1, wherein tubular web W is transferred while being pulled by a pair of cross seal jaws 7 moving downward, in the process of pressing the abovementioned web W from the direction orthogonal to the lengthwise direction of tubular web W by the pair of cross seal jaws 7. At this time, while web Wa (FIG.11) is being nipped between a pair of jaws 7b of the cross seal jaw 7, the lug folding flaps 7c folds the lug parts Wb formed at the web W at an appointed angle. Therefore, tubular web W is transferred downward by movement and folding while the web W is nipped by a pair of cross seal jaws 7 in the tube forming device 3. However, after the pair of cross seal jaws 7 carry out feeding of web W for an appointed distance while going downward, they repeat an elevating movement. On the other hand, the tension pressing device 2 is to control the feed rate and feeding amount of web W inside the packaging container producing equipment or to apply tension to the web W at all times since the formability is worsened and the web feeding amount becomes unstable unless tension is applied to the web when tubular web in which a content is filled is formed to be square-column-like web W by forming members (not illustrated). FIG. 2 is a perspective view of tension pressing device 2. The tension pressing device 2 is provided with a dancer roller (rocking roller) 9 which is disposed between a feeding roller 10 driven by drive means 8 having a clutch to send out web W in the transfer direction and a guide roller 11 and is rockable in the direction almost orthogonal to the web transfer direction; a pair of rocking arms 12 which have the abovementioned dancer roller 9 at its tip end and causes the dancer roller 9 to rock; a rotating shaft 13 secured at the base of the abovementioned pair of rocking arms 12, which transmits a drive force to the rocking arms 12; and a pneumatic cylinder 16 (a hydraulic cylinder or a motor other than a pneumatic cylinder may be acceptable) for driving said rotating shaft 13 via a lever 15. The pneumatic cylinder 16 is provided with a control valve 31 for stagelessly controlling the air pressure according to electric current proportional to the deviation between the rotation angle of the main shaft 6 (FIG.1) and the reference rotation angle. A control valve (not illustrated) which stagelessly controls the air pressure may be provided instead of the control valve 31. Furthermore, a pressing roller 17 which transmits a transfer force to web W transferred between the pressing roller 17 and the feeding roller 10 is provided at the position opposite the feeding roller 10. As shown in FIG. 2, although the rotating shaft (not illustrated) of the feeding roller 10 and guide roller 11 is supported at the wall of germfree chamber 18, the dancer roller 9 is not supported at said wall. The dancer roller 9 is able to move in the direction almost orthogonal to the feeding direction of web W with respect to rocking of the rocking arm 12. In a preferred embodiment of the invention, differing from prior arts described in FIG.9 and FIG.10, since the folding angle of the lug folding flap 7b (provided at only one cross seal jaw 7 of a pair of cross seal jaws 7 consisting of two sets) of the cross seal jaws 7 is set to an appointed angle, the following method to adjust the tension pressing force onto web W exclusively by the web tension pressing device 2 is employed as a method for adjusting the feeding amount of web W to solve a slip of printing patterns on web W. The method has a construction in which the tension pressing force of the dancer roller 9 to web W is continuously controlled by the tension pressing device 2. As shown in FIG.2, a pneumatic cylinder 16 for driving the abovementioned rocking arm rocking shaft is provided at the rocking arm 12 having a dancer roller 9 at its tip end, wherein a control valve 31, for example, an electro-pneumatic proportional valve which is able to stagelessly control the air pressure according to the intensity of electric current is employed thereat, and by this control valve 31, an electric current having intensity proportional to the size of the deviation value a detection mark a such as a printing pattern on web W from the abovementioned reference position of the mark position is inputted to stagelessly change the air pressure of the pneumatic cylinder 16 for driving the rocking arm rocking shaft, thereby causing the tension applied onto web W to be controlled and its feeding amount to be adjusted. At this time, as described above, an air pressure change valve which is able to control the air pressure in multistage may be employed as the control valve 31. FIG.5 shows a block diagram of a control device which controls a pressing force of web tension pressing device by the control valve 31. A detector 19 of detection mark a (FIG.4) of web W is provided in the vicinity of cross seal jaws 7 of tube forming device 3 (FIG.1), and the main shaft 6 is provided with an encoder 22 (FIG.1, FIG.4). As a detection mark a of web W passes at the detector 19, the detection mark a is read by the detector 19. Data read by the detector 19 is inputted into the main shaft rotation angle judging circuit 33 of the control device 23. Furthermore, the rotation angle of the main shaft 6 detected by the encoder 22 is inputted into the main shaft rotation angle judging circuit 33. The main shaft rotation angle judging circuit 33 regards the rotation angle of main shaft 6 as the mark detected angle at the point of time when data of the detection mark a read by the detector 19 is inputted. The data of the detector 19 is inputted into a production control circuit 35 and may be used as data for production control. The detected angle of the main shaft 6 is inputted into the subtracter 36. Since the reference angle (rotation angle which becomes a reference, established in advance, of the main shaft detected by the encoder 22 when the detection mark a of web W passes at the detector 19) is inputted into the subtracter 36, the deviation between the detected angle and the reference angle is obtained, and the deviation value is inputted into a corrective value calculation circuit 38. A corrective value for the abovementioned deviation value is obtained by the corrective value calculation circuit 38, and an electric signal corresponding to the obtained corrective value is outputted from the control device 23 to the control valve 31 of the tension pressing device 2, thereby causing the air pressure to be stagelessly changed, wherein the pressing force onto web W is controlled to stagelessly change the feeding amount of web W, and then an optimal feeding amount of web W is obtained. Thus, the tension for pressing web W is changed, using the pneumatic cylinder 16 for driving the rocking arm rocking shaft of the tension pressing device 2, and a slip of the detection mark a such as a printing pattern of web W is absorbed, wherein it is possible to further widen the correctable range of the web W feeding amount than in the prior arts, regardless of that the mechanism feeding amount of web W by cross seal jaws 7 per time is fixed. As described above, according to a preferred embodiment of the invention, since the pressing force of web is escalationally or stagelessly controlled by the web tension pressing device 2, the allowance range of a corrective feeding action of the web W feeding amount can be further widened than in the prior arts, wherein even though a change of the web W feeding amount is greater than in the prior arts, no faulty product is produced. Next, a description is given of another preferred embodiment in which, by controlling the pressing force onto web by the abovementioned web tension pressing device 2, it is possible to operate the feeding roller 10 (FIG.2) at two speeds, high speed and low speed, in addition to adjustment of the web W feeding amount, and tension fluctuation is decreased by securing the amount of accumulation of the web W tension. Since the web transfer channel is long, the web treads a complicated channel with its transfer direction changed many times, and the distance is long, a transfer force of the feeding roller 10 is used in addition to the web transfer force of cross seal jaw 7. However, it is remarkably difficult to completely coincide the web feedrate with the feedrate of the web feeding roller 10 by the cross seal jaw 7. Therefore, in order that the tension or feedrate of web at the tension pressing device 2 including the feeding roller 10 does not influence the web feedrate at the cross seal jaw 7, it is necessary to secure the amount of accumulation by the tension pressing device 2 consisting of web feeding roller 10, etc., so as to correspond to changes of the feedrate of web W due to the cross seal jaw 7. Therefore, it is constructed that a rocking type dancer roller 9 is provided at the feeding roller 10 part and the feeding roller 10 is able to be changed to high-speed operation and low-speed operation. Thereby, the tension applied onto web W can be controlled and kept to be fixed. When the feeding roller 10 is operated at a low speed, the dancer roller 9 is slowly elevated, and when the dancer roller 9 reaches the upper dead point, the feeding roller 10 is changed to a high-speed operation to cause the feeding amount of web to be increased. The dancer roller 9 is slowly lowered. When the dancer roller reaches the lower dead point, it is changed to a low-speed operation again to cause the feeding amount (feedrate) of web W per unit time to decreased. Then, the dancer roller 9 is elevated to cause the tension operating on the web W to be controlled and kept to be fixed. With reference to FIG. 2, a detailed description is given of a mechanism of controlling and keeping the tension operating onto web W to be fixed by changing the feeding roller 10 to high-speed or low-speed operation, wherein although the feeding roller 10 is driven by a drive means 8 having a clutch, the transfer force for web W is generated while the web W is being nipped between the feeding roller 10 and pressing roller 17. The pressing roller 17 is able to give a pressing force to the feeding roller 10 by using a fluid cylinder (not illustrated). Furthermore, rotation shaft 13 of the rocking arm 12 of the dancer roller 9 is provided at the wall of the germfree chamber 18 so as to penetrate the wall, and an operating arm 20 is fixed outside the wall of the corresponding chamber, wherein the operating arm 20 is elongated in a direction parallel to the rocking arm 12. The upper-limit position detector 21a and lower-limit position detector 21b are respectively provided at the outer wall side of the germfree chamber in the vicinity of the operating area at the tip end of the operating arm 20. Although the driving means 8 of the feeding roller 10 is operated at two stages, high speed and low speed, web W is intermittently sent in the process of forming it from tubular web W to hexahedral packaging containers C (FIG.1). If it is assumed that it is continuously sent, the feeding amount per unit time is made a reference feeding amount. In this case, the operating speed of the driving means 8 is established so that the feeding amount of web W by the feeding roller 10 exceeds the reference feeding amount when the driving means 8 is operated at the high speed, and the feeding amount of web W by the feeding roller 10 becomes less than the reference feeding amount when the driving means 8 is operated at a low speed. Since the feeding amount of web W by the feeding roller exceeds the reference feeding amount if it is assumed that the driving means 8 is operated at the high speed, the web W is slackened, and the slackening thereof is gradually increased, and the dancer roller 9 is caused to go down by a pressing force of the pneumatic cylinder 16. Therefore, the rocking arm 12 rotates downward centering around its rotating shaft 13, and the operating arm 20 rotates in the same direction as that of the rocking arm 12 via its rotation shaft 13. In the meantime, as the tip end part of the operating arm 20 reaches the position opposite the lower limit position detector 21b, the same detector 21b detects this. At this time, the same detector 21b outputs a lower limit position signal, and the control device 23 changes the high speed operation of the driving means 8 to the lower speed operation on the basis of the output signal. If so, since the feeding amount of web W by the feeding roller 10 becomes less than the reference feeding amount this time,, the slackening of web W is gradually decreased, and the dancer roller 9 is elevated by being pulled by the web W. At this time, the operating arm 20 rotates in the reverse direction of the abovementioned direction, and as the tip end part comes to the position opposite to the upper limit position detector 21a, the same detector 21a outputs an upper limit position signal, wherein the driving means 8 is changed from the low speed operation to the high speed operation again. Thus, although the dancer roller 9 repeats vertical movements in a range that the upper limit position and lower limit position detectors 21a, 21b detect the operating arm 20, web W is given tension resulting from the pressing force by the pneumatic cylinder of the dancer roller 9 in the meantime, wherein the web W is continuously sent at all times. Therefore, it is possible to keep the tension, applied onto the web W, fixed at all the times. Furthermore, since the upper limit and lower limit detectors 21a, 21b are disposed outside the germfree chamber 18, any trouble of the upper and lower limit position detectors 21a, 21b resulting from high temperature inside the germfree chamber 18 can be eliminated. As described above, according to the invention, the allowance range of the corrective action of web feeding amount by the cross seal jaws 7 can be further widened than in the prior arts by controlling the web tension pressing force, and if a change (error) of the feeding amount of web W is greater than in the conventional examples, no faulty products can be produced.

Claims: Packaging container production equipment for forming tubular web from sheet-like web and producing hexahedral packaging containers, by comprising: a web tension pressing means (9-12) provided with a rocking arm (12) and a rocking roller (9) secured at the tip end thereof, arranged to rock in the vertical direction and transfer sheet-like web while pressing the sheet-like web by the rocking roller (9) and a web feeding roller (10) to feed sheet-like web; a drive means (8) to drive the web feeding roller (10); a web tension pressing force setting means (16, 31) for setting the pressing force of said tension pressing means (9-12); a sealing member (7c) for forming sealing parts at tubular web by pressing both sides of the tubular web while folding both the sides of said tubular web in the direction orthogonal to the lengthwise direction of the tubular web obtained from sheet-like web, and simultaneously transferring web at an appointed feeding amount; a mark detecting means (19) for detecting that specified detection marks which will be targets on the web are fed onto the points of detection which will be the specified references established in advance; and characterized by further comprising a web tension pressing force controlling means (23) provided with position detecting means (21a, 21b) for detecting the upper-limit position and lower-limit position of the rocking roller (9), and means by which, on the basis of position detection of the upper-limit position and lower-limit position of the rocking roller (9) of said position detecting means (21a, 21b), the sheet-like web feeding amount by the feeding roller (10) is changed to a high-speed setting value and a low-speed setting value, for escalationally (stepwise) or continuously adjusting the pressing force set value of web tension pressing force setting means (16, 31) to an optimal value in response to the deviation between a timing when said specified mark detecting means (19) detects a specified detection mark on said web at a specified point, and a timing when a specified printing detection mark is detected, which will be a reference established in advance at said specified point of detection. A packaging container production method for forming tubular web from sheet-like web and producing hexahedral packaging containers, which is characterized by comprising the steps of: transferring sheet-like web while controlling a tension pressing force to an optimal value with respect to the sheet-like web forming tubular web from the sheet-like web being transferred; nipping both the sides of the tubular web in the direction orthogonal to the lengthwise direction said tubular web and forming a sealing part at the tubular web by folding the same, and simultaneously transferring web at an appointed feeding amount; and characterized by the further steps of: changing the sheet-like web feeding amount between a high-speed setting value and a low-speed setting value of when the upper limit position and lower limit position, established in advance, of an elevating member (20) are respectively detected according to a pressing force applied on to the sheet-like web; and continuously or escalationally (stepwise) controlling the web tension pressing force so as to become an optimal value in compliance with the deviation between the timing when a specified detection mark on the web is sent to a point of detection which becomes a specified reference established in advance and the timing when a specified detection mark is detected, which will be the reference established in advance at said specified point. A control system for a packaging container equipment according to Claim 1, comprising web tension pressing means (9-12), web tension pressing force setting means (16, 31), mark detecting means (19) and web tension pressing force controlling means (23) as defined Claim 1.

Inventors: FUJIMOTO AKIMASA, UEDA MICHIO, YAMAMOTO HIDEKIMI, FUJIMOTO, AKIMASA, UEDA, MICHIO, YAMAMOTO, HIDEKIMI, Fujimoto, Akimasa, c/o Shikoku Kakoki Co., Ltd., UEDA, MICHIO, C/O SHIKOKU KAKOKI CO., LTD., Yamamoto, Hidekimi, c/o Shikoku Kakoki Co., Ltd.
Applicants: SHIKOKU KAKOKI CO LTD, SHIKOKU KAKOKI CO., LTD
Application year: 1998
Main classification: B31B37
IPC codes: B31B19, B65B9, B31B1