CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 application of an international PCT application serial no. PCT/JP2019/003824, filed on Feb. 4, 2019, which claims the priority benefit of Japan application JP2018-029760, filed on Feb. 22, 2018. The entirety of the abovementioned patent application is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The present invention relates to a bag making apparatus and a method for making a plastic bag.

BACKGROUND ART

A bag making apparatus, for example, superposes a first sheet panel and a second sheet panel on each other and intermittently feeds them in their longitudinal direction. The apparatus supplies a side gusset to the first or second sheet panel during every intermittent feed cycle of the first and second sheet panels before superposing of the sheet panels such that the side gusset is interposed between the first and second sheet panels when the first and second sheet panels are superposed on each other.

Subsequently, during every intermittent feed cycle of the first and second sheet panels, the bag making apparatus heat-seals the first and second sheet panels in the longitudinal direction of the first and second sheet panels, and further heat-seals the first and second sheet panels and the side gusset in the width direction of the first and second sheet panels. Subsequently, the apparatus cross-cuts the first and second sheet panels and the side gusset in the width direction of the first and second sheet panels. Thereby, the apparatus makes a plastic bag.

Some bag making apparatuses, when making a plastic bag having an end face part (top face part or bottom face part), can punch the first and second sheet panels using the punch device such that corner cut parts are formed in the end face part. It is well known that the corner cut parts improve the safety of the plastic bag.

In this case, the bag making apparatus, for example, folds the sheet panel along a fold line to form a folded part in the sheet panel, and further folds back the folded part along the centerline of the folded part. The apparatus punches the folded part in this state using a punch device to form the corner cut parts. Therefore, when the plastic bag is made as described above, the end face part is formed by the folded part, and the corner cut parts are formed at the four corners of the end face part.

As disclosed in Patent documents 1-4, some bag making apparatuses can make a plastic bag including a functional part (such as a handle, a protruding part having an opening) on the end face part. In this case, if the corner cutting process is applied in the above way, the functional part is also cut.

An object of the present invention is to provide a bag making apparatus and a method for making capable of applying a corner cutting process to an end face part even when making a plastic bag including a functional part on the end face part.

CITATION LIST

Patent Document

[Patent Document 1] Japanese Patent Publication No. 4526592

[Patent Document 2] Japanese Patent Publication No. 6025338

[Patent Document 3] Japanese Patent Publication No. 5965509

[Patent Document 4] WO2018/012542

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a bag making apparatus including: a sheet panel feed device configured to superpose a first sheet panel and a second sheet panel on each other and to intermittently feed the first and second sheet panels in a longitudinal direction of the first and second sheet panels; and a side gusset supply device configured to supply a side gusset to the first or second sheet panel to dispose the side gusset in a width direction of the first and second sheet panels during every intermittent feed cycle of the first and second sheet panels before superposing of the first and second sheet panels such that the side gusset is interposed between the first and second sheet panels when the first and second sheet panels are superposed on each other. The apparatus further includes a sheet panel guide device configured to guide the first and second sheet panels as the first and second sheet panels are fed, such that the first sheet panel is folded along a first fold line on a side of a side edge thereof to form a first folded part therein, such that the second sheet panel is folded along a second fold line on a side of a corresponding side edge thereof to form a second folded part therein, such that the first folded part is superposed on the second folded part, and such that the first and second folded parts are folded back along the second fold line to form a folded-back part in the first sheet panel. The apparatus further includes a corner cut device configured to cut the second sheet panel and the folded-back part to form corner cut parts during every intermittent feed cycle of the first and second sheet panels after folding back of the first and second folded parts. The corner cut device is further configured to prevent cutting a base part of the first sheet panel and the first folded part when cutting the second sheet panel and the folded-back part.

The corner cut device may include: a cutter; and a baffle plate opposed to the cutter and located between the first folded part and the folded-back part to receive the cutter when the second sheet panel and the folded-back part are cut with the cutter.

The corner cut device may include: a cutter; a toggle mechanism configured to linearly reciprocate the cutter; and a cylinder for operating the toggle mechanism.

The toggle mechanism may include: a driving slider supporting the cutter and disposed movably in a moving direction of the cutter; a first link rotatably attached at one end thereof via a fixing pin; and a second link rotatably attached to the driving slider at one end thereof via an action pin. The first and second links may be rotatably linked to each other at the opposite ends thereof via a link pin. The cylinder may be connected to the link pin.

The corner cut device may further include an adjustment mechanism configured to adjust a bottom dead center of the cutter in the moving direction.

The adjustment mechanism may include: an adjustment slider supporting the fixing pin and disposed movably in the moving direction; an adjustment bolt attached to the adjustment sider and extending in the moving direction; and an adjustment nut screwed with the adjustment bolt. The adjustment mechanism may be configured such that rotation of the adjustment nut causes the adjustment bolt to move in the moving direction.

The cutter may be a Thomson die cutter, for example.

The bag making apparatus may further include: a longitudinal seal device configured to heat-seal the first and second sheet panels in the longitudinal direction during every intermittent feed cycle of the first and second sheet panels after superposing of the first and second sheet panels; and a cross seal device configured to heat-seal the first and second sheet panels and the side gusset in the width direction during every intermittent feed cycle of the first and second sheet panels after superposing of the first and second sheet panels.

The bag making apparatus may further includes a cross cut device configured to cross-cut the first and second sheet panels and the side gusset in the width direction during every intermittent feed cycle of the first and second sheet panels after heat seal with the longitudinal seal device and the cross seal device.

According to another aspect of the present invention, there is provided a method for making a plastic bag using the bag making apparatus, the method including: making the plastic bag from the first and second sheet panels and the side gusset, the plastic bag including an end face part and a protruding part, the end face part having the corner cut parts and being formed by the first folded part and the folded-back part, the protruding part protruding from the end face part and being formed by the base part of the first sheet panel and the first folded part.

According to yet another aspect of the present invention, there is provided a method for making a plastic bag, the method including: superposing a first sheet panel and a second sheet panel on each other and feeding the first and second sheet panels in a longitudinal direction of the first and second sheet panels; and supplying a side gusset to the first or second sheet panel to dispose the side gusset in a width direction of the first and second sheet panels during every intermittent feed cycle of the first and second sheet panels before superposing of the first and second sheet panels such that the side gusset is interposed between the first and second sheet panels when the first and second sheet panels are superposed on each other. The method further includes guiding the first and second sheet panels as the first and second sheet panels are fed, such that the first sheet panel is folded along a first fold line on a side of a side edge thereof to form a first folded part therein, such that the second sheet panel is folded along a second fold line on a side of a corresponding side edge thereof to form a second folded part therein, and such that the first folded part is superposed on the second folded part. The method further includes: heat-sealing the first and second sheet panels in the longitudinal direction during every intermittent feed cycle of the first and second sheet panels after superposing of the first and second sheet panels; and heat-sealing the first and second sheet panels and the side gusset in the width direction during every intermittent feed cycle of the first and second sheet panels after superposing of the first and second sheet panels. The method further includes cutting a base part of the first sheet panel and the first folded part in a state in which the first and second folded parts are not folded back, to form corner cut parts during every intermittent feed cycle of the first and second sheet panels after superposing of the first and second folded parts. The method further includes cross-cutting the first and second sheet panels and the side guest in the width direction during every intermittent feed cycle of the first and second sheet panels after heat seal and formation of the corner cut parts, so as to make the plastic bag from the first and second sheet panels and the side gusset, the plastic bag including an end face part and a protruding part, the end face part having the corner cut parts and being formed by the first folded part, the protruding part protruding from the end face part and being formed by the first and second folded parts.

