JP3051881U - Synthetic resin bag making machine - Google Patents

Abstract

(57) [Problem] To provide a bag making machine for synthetic resin bags that can reliably form a clean and high-strength seal portion (shrinkage seal portion) with a relatively simple structure. A sealing tension including a swingable bar (5a) having a length traversing the width direction of a synthetic resin film and an actuator (5c) is provided upstream of a heat sealing mechanism (2) of a bag making machine for garbage bags. A control mechanism 5 is provided to move the bar 5a to press the synthetic resin film in the thickness direction immediately before the start of sealing, and to move the bar 5a away from the synthetic resin film at the end of sealing, thereby shrinking the heat sealing portion and projecting. The shape of the seal portion is formed.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a bag making machine made of a synthetic resin film.

When manufacturing various bags such as garbage bags using a synthetic resin film, a tube-shaped synthetic resin film is unwound from a coiled raw material, and a required portion of the tube-shaped synthetic resin film is removed. A step of heat sealing in a band shape or a line shape with a width of 1 to 2 mm, and then cutting the synthetic resin film along the sealing portion downstream from the heat sealing is performed. Since the seal part constitutes the bottom of the bag, it is an important part that determines the quality of the product, and requires good strength. For this reason, it is preferable that the heat sealing be performed with the film in tension. In this case, tension is given to the downstream side because there is a pitch feed mechanism that feeds the tube-shaped synthetic resin film after sealing to a required pitch length downstream for cutting. However, on the upstream side, in the past, a bar was always provided that was always in contact with the tube-shaped synthetic resin film, and thus only the tension was applied.

[0003] For this reason, at the time of heat sealing, tension is applied to a predetermined portion to obtain a proper appropriate seal. However, even at the stage where the heat sealing is completed, the tubular synthetic resin film is pulled from the upstream side by the bar. Will be. For this reason, the seal portion is stretched by being pulled in a semi-molten state where cooling and solidification does not end, thereby making the seal portion concave and reducing the seal thickness. There was a problem of lowering. As a countermeasure, air was blown to the seal at the end of the seal to forcibly cool the seal.However, the air lowers the temperature of the seal blade, making the heat seal insufficient or unreliable, There were problems in that they vibrated or moved due to air, and that loud noise was generated due to the blowing of air. As another measure, an auxiliary pinch roller mechanism may be provided far upstream of the heat seal mechanism, and one of the pair of rollers of the auxiliary pinch roller mechanism may be floated immediately before the end of the pitch feed. However, the mechanism itself is complicated and large, and additional means for operating the seal roll and the downstream pinch roll mechanism are required separately. was there.

[0004]

[Problems to be solved by the invention]

 The present invention has been made in order to solve the above-mentioned problems. The purpose of the present invention is to ensure a clean and high-strength seal portion (shrinkage seal portion) with a relatively simple structure. Another object of the present invention is to provide a bag making machine for synthetic resin bags which can be formed at a time.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a heat seal mechanism provided with a synthetic resin film receiver and a seal knife that moves forward and backward toward the path for moving the synthetic resin film in the form of a tube. A pitch feed mechanism for nipping the synthetic resin film downstream and feeding the synthetic resin film at a pitch downstream thereof, and a cutting mechanism for cutting the synthetic resin film near the heat seal portion. A swingable bar having a length traversing the width direction of the resin film and the bar are moved so as to press the synthetic resin film in the thickness direction immediately before the start of sealing, and are separated from the synthetic resin film at the end of sealing. And a seal tension control mechanism provided with an actuator that moves like this.

Preferably, the sealing tension control mechanism has timing detecting means for operating an actuator in association with the driving means of the heat sealing mechanism, and the timing detecting means completes the pitch feed of the synthetic resin film. The actuator detects the timing at which the seal knife of the seal mechanism starts descending toward the seal roll, and the timing immediately before the pitch is started when the seal knife of the seal mechanism is separated from the seal roll after the seal is completed. Is activated.

In a first preferred example, a hydraulic cylinder is used as an actuator, a bar is connected to an operating rod of the hydraulic cylinder via a swing arm, and a driving means of a heat sealing mechanism is a cam. And a timing detecting means for detecting a rotation angle of the cam. As a preferred second example, the actuator and the timing detecting means include a cam attached to the driving means of the heat sealing mechanism, a follower in contact with the cam, and a lever operated by the cam. Are connected via a swing arm.

[0008]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 and 2 show a first embodiment of a synthetic resin bag making machine according to the present invention. Reference numeral 1 denotes a frame of the bag making machine, which has a mount 100 at the rear end of which is mounted a replaceable raw material F 'in which a tubular synthetic resin film F is wound in a coil shape. A protruding base 101 is provided on a frame downstream of the gantry 100, and a guide roll 102 for pulling up the synthetic resin film is arranged on the protruding base 101, and the synthetic resin film is guided substantially horizontally downstream of the guide roll 102. Guide bars 103 and 104 are arranged at intervals.

Reference numeral 2 denotes a seal mechanism provided on the frame 1 downstream of the guide bar 104. The seal mechanism 2 includes a seal roll 2a that is freely rotatable so that an outer peripheral surface made of an elastic material is positioned at a level that is appropriately higher than a movement level of the synthetic resin film, and a seal roll 2a above the seal roll 2a. And a drive means 2c for moving the seal knife 2b forward and backward. Although not shown, the seal knife 2a has a built-in heater, and the seal roll 2a also has a built-in heater in the elastic material or in the center shaft, and applies appropriate heat to the lower surface of the synthetic resin film. ing. In this embodiment, the driving means 2c includes a motor 20 provided at a lower portion of the frame 1, a cam 21 provided on an eccentric shaft 201 rotated by the motor 20, and a rotation of the cam 21 converted into a linear motion. And a link-shaped lever 22 that transmits the signal to the seal knife 2b.

Reference numeral 3 denotes a pitch feed mechanism provided on the frame 1 downstream of the seal mechanism 2, and a pair of main rollers 3 a and 3 a ′ for sandwiching the synthetic resin film in the thickness direction, and downstream of these. It has a pair of sub-rollers 3b, 3b 'positioned thereon and a plurality of belts 3c, 3c' stretched between the main rollers 3a, 3a 'and the sub-rollers 3b, 3b'. A drive wheel 30 is attached to the shaft, and the drive wheel 30 is connected to a servomotor 3d at the lower portion of the frame via a belt, a chain, or the like so that the synthetic resin film is fed at a desired pitch. Has become. A driven wheel 26 is attached to the center shaft end of the seal roll 2a as shown in FIG. 2, and an interlocking belt or chain 32 is provided between the driven wheel 26 and the driven wheel 31 on the opposite side from the drive wheel 30. When the main rollers 3a and 3a 'rotate, the seal roll 2a is also rotated in conjunction with the rotation.

Reference numeral 4 denotes a cutting mechanism provided downstream of the pitch feed mechanism. The cutting mechanism is optional, but in the embodiment, a fixed blade 4a located on the lower surface side of the synthetic resin film and an upper portion adjacent thereto are fixed. The movable blade 4b is attached to a link-shaped lever 42, which is connected to the cam 21 of the driving means 2c of the seal mechanism 2 so that the movable blade 4b Is driven in synchronization with the seal knife 2b so as to cut the synthetic resin film on which the seal portion is formed in the width direction.

Reference numeral 5 denotes a sealing tension control mechanism which is a feature of the present invention, and is provided near and upstream of the sealing mechanism 2. The sealing tension control mechanism 5 includes a bar (or rod) 5a having a circular cross section which is supported by the swinging arms 5b, 5b and is orthogonal to the film feeding direction so as to cross the entire width of the synthetic resin film. A translation type actuator 5c is provided for forcibly moving the bar 5a in the thickness direction (vertical direction) of the synthetic resin film at a predetermined time via the swing arms 5b, 5b.

In this embodiment, a hydraulic cylinder 5c is used as an actuator, and the hydraulic cylinder is fixed to a bracket 10 provided on the frame 1 with the operating rod 50 facing upstream. A support shaft 51 constituting a swing fulcrum is horizontally suspended at a position separated from the bar 5a. The support shaft 51 is at a higher level than the fluid pressure cylinder 5c, and bell crank-shaped swing arms 5b, 5b each having one end connected to a bar 5a are supported on the support shaft 51 in a tiltable manner. . A connecting member 52 is connected to the lower ends of the swing arms 5b, 5b, and the distal end of the operating rod 50 is connected to the connecting member 52.

The bar 5a presses the synthetic resin film F in the thickness direction to add tension by the operation of the swing arms 5b, 5b by the fluid pressure cylinder 5c, and releases the tension by releasing the press. Work to do. The operation of the bar 5a is interlocked with the sealing operation by the sealing mechanism 2, and therefore, the hydraulic cylinder 5c should be interlocked with the operation of the sealing knife 2b, as shown in FIG. A timing detecting means 5d is provided at a main part of the means 2c, and the timing detecting means 5d is connected to a drive control unit 53 including a valve, for example, an electromagnetic valve and an energizing switch for the valve, so as to start and stop the hydraulic cylinder 5c. ing.

The timing detecting means 5 d is, specifically, a cam in which the pitch feeding of the synthetic resin film is completed and the rotation of the cam 21 causes the seal knife 2 b of the seal mechanism 2 to start descending toward the seal roll 2 a. The first angle is detected and a signal is sent. After that, the sealing is completed and the rotation of the cam 21 causes the sealing knife 2b of the sealing mechanism 2 to be separated from the sealing roll 2a, and the cam second angle immediately before the start of pitch feeding. It is for detecting and sending a signal. Any type of signal that can emit such a signal may be used. For example, a switch (contact type switch, proximity switch, etc.) or an encoder is used. These are provided on the camshaft or on the outer surface of the cam.

When the drive control unit 53 receives the first cam angle signal, it operates a valve to send fluid to the piston side of the fluid pressure cylinder 5c to operate the operating rod 50 to the extension side in this example, The swing arms 5b, 5b are operated in the falling direction. When the second cam angle signal is received, the fluid is sent to the rod side of the fluid pressure cylinder 5c to actuate the operating rod 50 to the shortening side, and to operate the swing arms 5b, 5b in the upright direction. Circuit. This circuit may be a relay or the like or a CPU.

Reference numeral 6 denotes a tension applying mechanism provided downstream in the vicinity of the sealing mechanism 2. The tension applying mechanism 6 operates the sealing tension control mechanism 5 to apply tension to the synthetic resin film by the bar 5a. When this is done, the synthetic resin film F is tensioned on the seal roll 2a in cooperation with the bar 5a. Therefore, the bar 6a is held at a position appropriately lower than the film contact level with the seal roll 2a so as to always apply a predetermined tension to the synthetic resin film F.

In this embodiment, the tension applying mechanism 6 includes a bar 6a supported by the swing arms 6b, 6b and an actuator 6c for changing the angle of the swing arms 6b, 6b, similarly to the tension control mechanism. Has become. The reason is that the degree of application of the tension can be changed according to the strength of the synthetic resin film to be used, and if the feeding of the synthetic resin film is stopped due to any trouble, This is because the close contact of the synthetic resin film with the seal roll 2a can be released. However, in some cases, the tension applying mechanism 6 may be a fixed position bar similar to the second embodiment described later.

FIG. 3 shows a second embodiment of the present invention. Also in this example, the sealing tension control mechanism 5 includes a bar (or rod) 5a having a circular cross section, which is supported by the swinging arms 5b and 5b and is orthogonal to the film feeding direction so as to cross the entire width of the synthetic resin film. An actuator 5c for forcibly moving the bar 5a in the thickness direction (vertical direction) of the synthetic resin film at a predetermined time via the swing arms 5b, 5b is provided. A mechanical one is used instead of a cylinder. That is, a support shaft 51 constituting a swing fulcrum is horizontally mounted on the frame 1 at a position separated from the bar 5a, and a substantially linear swing shaft having one end connected to the bar 5a is provided on the support shaft 51. The moving arms 5b, 5b are tiltably supported. A connecting member 52 is connected to lower ends of the swing arms 5b, 5b, and a lever 54 is connected to the connecting member 52.

On the other hand, a plate-shaped cam 22 is coaxially mounted on the drive shaft 201 of the drive means 2c of the seal mechanism 2 separately from the cam 21 for moving the seal knife 2b and the cut knife 4b. A follower 23 is arranged on the outer periphery of the cam 22. The cam 22 and the follower 23 are actuator / timing detecting means in the second embodiment. The lever 54 is moved down the frame 1 so that its end is supported by a fulcrum, and the lever 54 is connected to the follower 23 at a position shorter than the end. The cam 22 has a predetermined cam shape, that is, a synthetic resin film. At the same time when the pitch feed is completed and the seal knife 2b of the seal mechanism 2 starts to descend toward the seal roll 2a by the rotation of the cam 21, the lever 54 is operated almost at the same time as the cam surface for moving the bar 5a to the falling side. When the seal is completed and the cam 21 rotates, the seal knife 2b of the seal mechanism 2 is separated from the seal roll 2a, and the lever 54 is operated immediately before the pitch feed is started to move the bar 5a to the upright side. Is provided. In the embodiment, the guide bar 7 whose position is variable is arranged between the tension applying mechanism 6 and the pitch feed mechanism 3, but this is not always necessary.

[0021]

Operation of the embodiment

 Next, the operation of the device of the present invention will be described according to the first embodiment. In the bag making, the synthetic resin film F is pulled out from the raw material F 'until it reaches the downstream of the cutting mechanism 2, and the operation is started. At this time, the fluid pressure cylinder 6c of the tension applying mechanism 6 is held at a predetermined driving position, whereby the swing arms 6b, 6b fall down at a predetermined angle, and the bar 6a holds the synthetic resin film F on the film of the seal roll 2a. It is pulled moderately below the contact level to provide initial tension. However, at this time, the tension control mechanism 5 is not operated, and the swing arms 5b, 5b are held at a standby angle that is more upright than the swing arms 6b, 6b of the tension applying mechanism 6. The standby angle is an angle at which the bar 5a comes into light contact with the synthetic resin film F.

Next, in this state, the pitch feed mechanism 3 is driven by the number of rotations set by the servo motor 3d, whereby the synthetic resin film F is stretched between the main rollers 3a, 3a 'and the sub rollers 3b, 3b'. The belts 3c, 3c 'are pulled out to the downstream side by their rotation. The seal roll 2a rotates in conjunction with the drive of the servo motor 3d. At this time, the bar 5a of the tension control mechanism 5 is in light contact with the synthetic resin film as described above. FIG. 4 shows this pitch feed step.

When the movement of the synthetic resin film is stopped after the feed of the predetermined pitch length is completed in this way, the motor 20 of the seal mechanism 2 is operated, and the cam 21 is rotated by the motor 20, whereby the cam 21 is rotated. The link-shaped lever 22 is operated to advance the seal knife 2b from the standby position toward the seal roll 2a. At the same time, on the downstream side, the lever 42 of the cutting mechanism 4 operates, and the movable blade 4b moves down in synchronization with the seal knife 2b.

The cam angle of the seal mechanism 2 is detected by the timing detecting means 5 d, and the detection signal is sent to the drive control section 53 at the moment when the seal knife 2 b starts moving forward or reaches the first cam angle indicating the state immediately after. Is sent. Upon receiving the signal, the drive control unit 53 supplies electricity to the solenoid valve of the hydraulic cylinder 5c, whereby the hydraulic cylinder extends and the swing arms 5b, 5b tilt about the support shaft 51 to the tilting side. Turn over. As a result, the bar 5a is lowered to a level substantially equal to the level of the bar 6a of the tension applying mechanism 6, and presses the synthetic resin film f near and upstream of the seal roll 2a downward. Due to this additional force, the synthetic resin film F is slightly pulled back to the upstream side, whereby the synthetic resin film F is corrected to an accurate pitch. At the same time, the synthetic resin film is tensioned by the pressing force in the thickness direction by the downstream and upstream bars 5a, 6a, so that the portion to be sealed and its front and rear portions are tensioned on the seal roll 2a. . This is the state of FIG.

The sealing knife 2b of the sealing mechanism 2 keeps descending and contacts the sealing roll 2a via the synthetic resin film F, whereby the synthetic resin film is heat-sealed over the entire width. FIG. 6 shows this state. Since the synthetic resin film F is given tension by the upstream and downstream flow bars 5a, 6a, an accurate and beautiful linear seal portion is formed. FIG. 8A shows the seal portion s1 at this stage in an enlarged manner, and is in a recessed state due to the pressing force and partial melting of the seal knife 2b under the application of tension.

When the seal knife 2b of the seal mechanism 2 comes into contact with the seal roll 2a in this manner, the continuous rotation of the cam 21 causes the link-shaped lever 22 to operate in the opposite direction (upward) to seal the seal knife 2b. Separate from the roll 2a. At the same time, in the downstream flow, the lever 42 of the cutting mechanism 4 operates in reverse, and the movable blade 4b starts to rise in synchronization with the seal knife 2b.

The cam angle causing the movement of the seal mechanism 2 is detected by the timing detecting means 5d, and the state in which the seal knife 2b starts to retreat (at this time, the pitch feed mechanism 3 has not been operated yet). The detection signal is sent to the drive control unit 53 at the moment when the second cam angle shown is reached. Upon receiving this signal, a drive command is issued from the drive control unit 53 to the solenoid valve of the fluid pressure cylinder 5c, whereby the fluid pressure cylinder 5c performs a shortening operation, and the swing arms 5b, 5b are pivoted about the support shaft 51. And tilt to the standing side.

As a result, the bar 5a is returned to the initial position, and the application of tension to the synthetic resin film f near and upstream of the seal roll 2a is released. This is the state shown in FIG. 7. For this reason, the synthetic resin film F is slackened, and the tensile stress applied to the seal portion s1 up to the upstream side disappears. The resin component in the state contracts, thereby forming a convexly-sealed seal portion s2 such that the thickness increases as shown in FIG. 8B. As a result, the sealing strength increases.

Next, the pitch feed mechanism 3 is driven by the number of rotations set by the servo motor 3d, whereby the synthetic resin film F is sent to the downstream side, and one cycle of bag making is completed. Since the bar 5a of the tension control mechanism 5 has been returned to the initial position, the synthetic resin film F comes into contact with the bar 5a of the tension control mechanism 5 by the feeding and the pressing state by the bar 6a of the tension applying mechanism 6. This returns to FIG. By repeating the above operation, a synthetic resin bag having a high-strength seal portion is manufactured.

In the second embodiment, when the pitch feeding of the synthetic resin film to the plate-like cam 22 ends, and the rotation of the cam 21 causes the seal knife 2b of the seal mechanism 2 to start descending toward the seal roll 2a. Almost at the same time, the first cam surface for operating the lever 54 to move the bar 5a to the tilting side is provided, so that the follower 23 follows the first cam surface, so that the lever 54 is moved. The swing arms 5b, 5b are tilted about the support shaft 51 to the falling side, and the synthetic resin film is tensioned by the pressing force in the thickness direction by the downstream and upstream bars 5a, 6a, and the sealing is scheduled. The part and its front and rear are in a state of being tensioned on the seal roll 2a.

After that, when the cam 22 continues to rotate, the seal is completed, and the rotation of the cam 21 causes the seal knife 2b of the seal mechanism 2 to separate from the seal roll 2a, and the second cam surface immediately before the pitch feed is started. The follower 23 follows, whereby the lever 54 is moved in the reverse direction, and the swinging arms 5b, 5b are tilted to the upright side around the support shaft 51, so that the bar 5a is returned to the initial position, and the sealing is performed. The tension application to the synthetic resin film f near and upstream of the roll 2a is released. As a result, the synthetic resin film F is slackened, so that the tensile stress applied to the seal portion s1 to the upstream side disappears, and the resin shrinks. As a result, as shown in FIG. Is increased so that the seal portion s2 is raised in a convex shape.

When it is not necessary to use a protruding shrink seal as shown in FIG. 8B, the drive control unit 53 is turned off in the first embodiment, and the cam 22 is connected to the shaft in the second embodiment. What is necessary is just to remove from 201. In this way, it is possible to perform bag making in which a stretch seal portion is formed as in the conventional case. In addition, it goes without saying that the present invention is not limited to the above embodiment.

[0033]

[Effect of the invention]

 According to the first aspect of the present invention described above, a swingable bar having a length traversing the width direction of the synthetic resin film is provided upstream in the vicinity of the heat sealing mechanism 2 in the tubular plastic resin film making machine. 5a and an actuator 5c for moving the bar 5a so as to press the synthetic resin film in the thickness direction immediately before the start of sealing and to move the bar 5a away from the synthetic resin film at the end of sealing. Since the mechanism 5 is provided, a proper heat tension can be applied to the film at the time of heat sealing to form a clean heat seal. In addition, the tension applied to the film is released after the heat sealing, so that the sealing portion shrinks. Excellent effect that the sealing part can be made thicker and convex, and the sealing strength can be reliably improved. Obtained.

According to the second aspect, the sealing tension control mechanism 5 has timing detecting means 5 d for operating the actuator 5 c in association with the driving means 2 c of the heat sealing mechanism 2, and the timing detecting means 5d, the pitch feed of the synthetic resin film ends, the timing at which the seal knife 2b of the seal mechanism 2 starts descending toward the seal roll 2a, and the end of the seal, and the seal knife 2b of the seal mechanism 2 turns the seal roll 2a. And the timing immediately before the pitch feed is started is detected, and the actuator 5c is actuated, so that the bar 5a can be automatically linked with the operation of the seal mechanism, so that the accurate timing is obtained. And the timing can control the tension of the film. You.

According to the third aspect, the actuator 5c is a hydraulic cylinder, the bar 5a is supported by the swing arms 5b, 5b, and the operating rod of the hydraulic cylinder is connected to the swing levers 5b, 5b. Since the driving means 2c of the heat sealing mechanism 2 has the cam 21 and the timing detecting means 5d is a switch or an encoder for detecting the rotation angle of the cam 21, the tension of the film can be adjusted at an accurate timing and timing. The excellent effect that not only can be controlled but also a compact sealing tension control mechanism 5 can be obtained.

According to the fourth aspect, the actuator 5c and the timing detecting means 5d include the cam 22 attached to the driving means 2c of the heat sealing mechanism 2, the follower 23 in contact with the cam, and the lever 54 moved by the cam. Since the bar 5a is connected to the lever 54 via the swing arms 5b, 5b, there is no need for control including a cylinder, a solenoid valve, and the like, and an excellent effect that costs can be reduced can be obtained. can get.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a first embodiment of a bag making machine for synthetic resin bags according to the present invention.

FIG. 2 is a plan view showing details of a tension control mechanism according to the present invention.

FIG. 3 is a side view schematically illustrating a second embodiment of the synthetic resin bag making machine according to the present invention.

FIG. 4 is an explanatory view showing a state at the time of film pitch feeding in the present invention.

FIG. 5 is an explanatory view showing a state immediately after the film pitch feeding is completed and just before the seal is started in the present invention.

FIG. 6 is an explanatory view showing a state at the time of sealing in the present invention.

FIG. 7 is an explanatory view showing a state in which the sealing is completed and immediately before pitch feeding in the present invention.

FIG. 8A is an enlarged cross-sectional view schematically illustrating a state of a sealing portion at the end of sealing. (B) is an enlarged sectional view schematically showing the state of the seal portion when the present invention is used.

[Explanation of symbols]

 Reference Signs List 1 frame 2 seal mechanism 3 pitch feed mechanism 4 cut mechanism 5 tension control mechanism 5a bar 5b swing arm 5c actuator 5d timing detection means 21 cam 22 cam 23 follower 54 lever

Claims (4)

[Utility model registration claims] A heat seal mechanism having a synthetic resin film receiver and a seal knife moving toward and away from the synthetic resin film is provided in a path for moving the synthetic resin film in a tubular shape, and the synthetic resin film is provided downstream of the heat seal mechanism. And a cutting mechanism for cutting the synthetic resin film in the vicinity of the heat-sealing portion, in which the width direction of the synthetic-resin film is adjusted upstream in the vicinity of the heat-sealing mechanism 2. A swingable bar 5a of a traversing length;
An actuator 5c for moving the bar 5a so as to press the synthetic resin film in the thickness direction immediately before the start of sealing and moving the bar 5a away from the synthetic resin film at the end of sealing is provided. A bag making machine for synthetic resin bags. 2. A sealing tension control mechanism 5 includes timing detecting means 5d for operating an actuator 5c in association with a driving means 2c of a heat sealing mechanism 2, and the timing detecting means 5d controls the operation of the synthetic resin film. The timing at which the pitch feed ends and the seal knife 2b of the seal mechanism 2 starts descending toward the seal roll 2a, and the seal knife 2b of the seal mechanism 2 after the seal ends
2. The synthetic resin bag making machine according to claim 1, wherein a timing immediately before the pitch feed is started by separating from the seal roll 2a is detected and the actuator 5c is operated. 3. An actuator 5c is a hydraulic cylinder, and a bar 5a is supported by swing arms 5b, 5b.
An operating rod of a fluid pressure cylinder is connected to the swinging levers 5b, 5b. The driving means 2c of the heat sealing mechanism 2 has a cam 21, and the timing detecting means 5d is
3. The bag making machine for a synthetic resin bag according to claim 2, which is a switch or an encoder for detecting a rotation angle of the bag. 4. The actuator 5c and the timing detecting means 5d comprise a cam 22 attached to the driving means 2c of the heat sealing mechanism 2, a follower 23 in contact with the cam, and a lever 54 moved by the cam.
3. A bag making machine for a synthetic resin bag according to claim 2, wherein a bar 5a is connected to said bar through swinging arms 5b.