JPS5815363B2 - Manufacturing method for canned food containing liquid nitrogen and nitrogen filling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a canned food containing liquid nitrogen, which aims to reduce the thickness of the canned container and prevent corrosion on the inside of the can by increasing the internal pressure of the canned container and removing residual oxygen inside the can. The present invention relates to a manufacturing method and a nitrogen encapsulation device directly used for carrying out the method.

As described in JP-A No. 52-116384, in order to reduce the thickness of conventional can containers and prevent corrosion on the inside of the can, a fixed amount of LN2 (liquid nitrogen) was dropped into the can filled with contents. The vaporized GN2 (nitrogen gas) drives out the O2 (oxygen) remaining in the space between the top of the contents and the can mouth (hereinafter referred to as headspace), prevents oxidation and corrosion of the contents and the inside of the can, and seals the can tightly. The internal pressure obtained later has been devised to withstand force majeure such as external pressure and impact.

In order to drip LN2 into the can body, LN2 is dripped by a nozzle just before the can seaming process, and if the seaming is completed while the generated GN2 flows out of the can body, it will be inside the can. This is done under the assumption that the remaining oxygen will be drained out along with it, and that high-quality canned goods with a predetermined pressure can be obtained.

This method is called the dropping nozzle method, and it can be carried out with relatively simple equipment, and is widely used as an extremely common method.

However, with this drip nozzle method, the expansion rate when LN2 vaporizes is extremely large, making it difficult to quantitatively control the amount of LN2 added.
A small change results in a significant difference in the amount of gas generated, resulting in large variations in the pressure inside the can after seaming, and there is still a problem in making the thickness of the can extremely thin.

On the other hand, although the proportion of residual air in the can (78% nitrogen, 21% oxygen, 1% other) and GN2 generated after dropping in the total gas volume decreases, complete removal cannot be expected; It has been confirmed through experiments that this causes oxidation and corrosion phenomena on the inside of objects and cans.

Specifically, the head space height is 11 mm, LN2
The amount of dripping was 0.3g, and the time from dropping to tightening was 16.0g.
When expressed in seconds, the internal pressure of the can is 0.15 to 4.2 kg/cm2.
The amount of oxygen varies from 3.14 to 11.36 m1.
In the case of no LN2 addition, the amount is 2.95 to 3.58 ml, which is an increase of 1 to 3 times.

The reason for this is that, as shown in Fig. 1, a fixed amount of LN2 is dripped from the LN2 supply source (not shown) into the head spaces H and S of the can body filled with content X (see step A) using the dripping nozzle y. Refer to process B], the gap γ between the can lid α and the can mouth β′ of the can body β is The GN2 vaporized from the can drives out the O2 inside the can and further prevents the intrusion of 02 outside the can [see step C].

However, depending on the behavior and amount of this vaporized GN2, the 0□ in the can may not be sufficiently expelled, the 0□ may enter at the same time as the GN2 flows out, or the can may be moved between stations before being tightened. It is believed that the 02 entrainment is caused by air flow around the outside of the can that occurs during seaming.

As a result, even if the amount of vaporized GN2 increases, it still remains inside the can body β after being tightened, and oxygen removal cannot be expected.

Thus, it is very difficult to equalize the internal pressure of all the cans and requires expensive and complicated equipment.

Therefore, when liquid nitrogen is used, it is difficult to simultaneously achieve the objectives of reducing plate thickness and preventing corrosion inside the can.

From the above-mentioned viewpoints, the present invention attempts to improve the conventional drip nozzle method using liquid nitrogen, and achieves both reduction of plate thickness and prevention of corrosion on the inside of the can, reducing cost of can containers and improving quality of canned goods. It is an object of the present invention to provide a method for manufacturing a can containing liquid nitrogen and a nitrogen filling device that achieve the above.

Thus, in order to achieve the above object, the present invention first drips a necessary amount of liquid nitrogen onto the can opening, where the can body filled with contents is transported to the step where the can lid is placed. In addition to expelling the existing oxygen 02, nitrogen gas is sprayed from the outside of the can lid and can mouth over the area where the conveyance movement locus of the can lid supply device and the conveyance movement locus of the can body overlap, and nitrogen gas is sprayed from the outside of the can lid and can mouth to remove oxygen 02 that cannot be sufficiently expelled. The synergistic action of the liquid nitrogen and the nitrogen gas removes the 02 inside the can and the 02 flowing into the can due to the air flow around the outside of the can during transportation or during seaming, and converts it into nitrogen. While seaming is performed in a gas atmosphere, the liquid nitrogen inside the can is vaporized by the nitrogen gas spray, controlling the amount of gas that evaporates in a certain period of time, blowing away excess nitrogen gas, and sealing the can. The pressure inside the can is then kept constant.

Therefore, it is possible to completely remove 02 in the can,
There is no variation in the internal pressure of the can, and the aforementioned objectives of reducing plate thickness and preventing corrosion on the inside of the can can be achieved.

A first embodiment of the method of the present invention will be described with reference to FIGS. 2 and 3.

First, the can β filled with content X in the conventional filling process is [
Refer to step A], while the cans are conveyed in a straight line by the can supply conveyor device A shown in Fig. 3, the required amount of LN2 is supplied to the dripping nozzle y, which hangs down to a predetermined position above the conveyance path R of the can supply conveyor device A. Dropped [see process row].

On the other hand, the can lid α is delivered from the can lid supply device Y to a pocket P on the outer periphery of the can lid feed turret device B and is held there, and when it reaches a predetermined position while being in a rotating conveyance state, the curved seat surface of the pocket P Nozzle block N fitted in, G from B1
N2 spraying is started [see process c].

Next, the LN that has passed through the inlet area Za of the nitrogen filling device Z
When the can body β after two drops and the can lid α sprayed with GN2 approach each other and the can lid α held in the pocket P starts to cover the can mouth β′ of the can body β, the can lid α The GN2 from the nozzle blocks N and B1 spraying onto α also flows into the can body β and removes 02 near the can mouth β' and head spaces H and S, and at the same time removes LN2 in the head spaces H and S. Forced vaporization is performed to control the amount of gas vaporized during a certain period of time, and to blow away excess GN2 [see step 2].

Then, until the can body β is covered with the can lid α, the GN
2 continues, the can body β and the can lid α are both enveloped in the GN2 atmosphere (see process E), and are delivered to the seaming device G, where they are supported by the lifter L and seaming chucks S and C at the top and bottom for seaming. The GN2 in the can body β will continue to flow out until the seaming work is completed in jigs S and R [see process].

After this, unvaporized LN2 is gradually vaporized in the canned can δ, which is sealed and sealed, and is sent to the next process by a discharge turret device while obtaining the necessary internal pressure.

A second embodiment of the method of the present invention will be described with reference to FIGS. 3 and 4.

First, the can β filled with content X in the conventional filling process is [
Refer to step A], while the cans are conveyed in a straight line by the can supply conveyor device A in FIG. [See process row].

Subsequently, nitrogen filling device 2 is supplied by can body supply conveyor device A.
When passing through the inlet area Za of the nozzle blocks N, B2. on both sides of the inlet area Za. GN2 is sprayed from N and B3 toward the can mouth β' of the can body β, and at the same time the residual air inside the can mouth β' is forced out, while the LN2 in the head spaces H and S is forcibly vaporized, 02 is injected from the outside. The process progresses while preventing the intrusion of [see step C].

On the other hand, the can lid α is delivered from the can lid supply device Y to a pocket P on the outer periphery of the can lid feed turret device B, and when it is held there and reaches a predetermined position while being in a rotating conveyance state, the arc extinguishing seat of the pocket P Spraying of GN2 is started from the nozzle blocks N and B1 fitted on the surface [see step 2].

Next, the can body β and G that have passed the inlet area Za of the nitrogen filling device Z
The can lid α that has been sprayed with N2 approaches each other and the can body β
When the can lid α held in the pocket P begins to cover the can mouth β', the nozzle blocks N and B spraying onto the can lid α
GN2 from 1 also flows into the can body β, removes O2 near the can mouth β1 head spaces H and S, and at the same time performs forced vaporization of LN2 in the head spaces H and S to vaporize within a certain period of time. The amount of gas is controlled and excess GN2 is blown away [see process e].

Then, GN2 is placed until the can body β is covered with the can lid α.
The can body β and the can lid α are both enveloped in the GN2 atmosphere [see process], and then transferred to the seaming device °C, where they are supported from above and below by the lifter L and seaming chucks S and C for seaming. The GN2 in the can body β continues to flow out until the seaming work is completed by the rolls S and R [see step G].

After this, unvaporized LN2 is gradually vaporized in the canned can δ, which is sealed and sealed, and is sent to the next process by a discharge turret device while obtaining the necessary internal pressure.

As described above, when GN2 is injected, the can body β is located in the inlet area Za.
This may be done either during the passage or just before placing the can lid α on the can mouth β', or when the temperature inside the can body β of LN2 is low, the contents may be filled in the filling process. The can body β may be sealed at any desired time until the seaming device C double-wraps the can lid α to the can mouth β'.

Next, examples of the nitrogen filling device of the present invention are shown in FIGS. 3 and 5.
A description will be given of FIGS. 6 to 6.

The nitrogen filling device 2 of the present invention has a can body β filled with contents X.
A can supply conveyor device A has a dripping nozzle y that conveys the group linearly at equal intervals and drips LN2 at a predetermined position above the transportation path R, and a can is delivered to one location from the can lid supply device Y. While spraying the lid α with GN2, the can mouth β of the can body β group
Can lid feed turret device B installed synchronously above
, a seaming device C that integrally seams together the can body β and the can lid α after being placed, and a discharge turret device that sends out the group of canned goods δ seamed by the seaming device C to the next process.

As shown in FIG. 3, the can supply conveyor device A sequentially receives the groups of cans β filled with the contents ．． A drive sprocket 1 fixed to the output shaft 1a of a drive motor (not shown) so as to pass through the inlet area Za provided with N and B3 and convey it to the external contact point θ2 of the can lid feed turret device B and seaming device C; A double-row roller chain 3 is stretched endlessly between two driven sprockets rotatably fixed to the terminal end of the material filling device,
The double-row roller chain 3 is equipped with four groups of feed pawls arranged at regular intervals for hooking and pushing the can body β, and furthermore, a group of four feed pawls for hooking and pushing the can bodies β are attached at equal pitches, and furthermore, a pair of feed pawls 4 guides both sides of the can body β being pushed by the feed pawls 4 above the double-row roller chain 3. The regulating entrance can guides 5a, 5b and stationary guide 5c are arranged parallel to each other to form and extend the conveyance path R, and the can body β group is sandwiched between the entrance can guides 5a, 5b and the stationary guide 5c. Can lid feed turret device B and seaming device C
is transported to the external contact point θ2.

A dropping nozzle y is vertically installed at a predetermined position above the conveyance path of the can body β so that LN2 can be freely dropped into the can body β filled with the contents Guide 5
Proximity switch S for can body β detection installed at the bottom of the starting end of a
If the arrival of the can body β is detected through 1, and the valve (not shown) of the dripping nozzle y is operated in conjunction with opening and closing,
The required amount of LN2 can be dropped into the can β.

Alternatively, it is also possible to conveniently leave the valve open and allow LN2 to drip at all times, and to drip the LN2 at a fixed rate by double the speed.

On the other hand, on the stationary guide 5c in the entrance area Za and the inlet can guide 5a sandwiching the transport path R therein, there are
Distribution chambers 7 and 8 communicating with a compressed nitrogen gas source (not shown) via a port 6 are provided inside, and a group of jet ports 9 and 10 communicating with the distribution chambers 7 and 8 are provided on opposing surfaces of the can mouth β of the can body β. 'Linear nozzle blocks N and B penetrated in two stages, upper and lower, corresponding to the height position.
2. N and B3 face each other in parallel.

Next, the can lid feed turret device B holds the group of can lids α delivered from the can lid supply device Y as shown in FIGS. When the can body is brought to the next seaming device C, GN2 is sprayed and the can lid α is placed on the can body β in synchronization with the can body supply conveyor device A and transferred to the next seaming device C by a driving device (not shown). A turret 12 is fixed to a turret shaft 11 that rotates in a direction, and two groups of semicircular arc-shaped pockets (10 pockets are shown in the figure) are provided on the outer periphery of the turret 12 at equal intervals. 13 groups of radial distribution slots are provided radially at equal intervals from the top to the second group of pockets, and a turret cover 14 and a center side end of each radial distribution slot 13 are provided in the upper surface of the radial distribution slots 13. Wear plates 15 extending longitudinally through each communicating air supply port 15a at equal intervals in the circumferential direction are respectively fitted,
Further, the group of fan-shaped nozzle blocks N and B1 fitted in the arc-extinguishing seat surface of the pocket P sprays GN2 toward the can lid α and can mouth β' of the can body β supported by the pocket P on the outer periphery of the turret 12. The supporting projecting ends 17 on both sides of the fan-shaped nozzle blocks N and B1, which are positioned by dowel pins 16 that are driven in from the top surface of the turret 12, are fixed with stoppers 18 and bolts 19, and the sides between adjacent fan-shaped nozzle blocks N and 81 are fixed with bolts 20, respectively. do.

These fan-shaped nozzle blocks N and B1 are connected to the turret 1.
A trapezoidal GN2 distribution groove 22 and an arcuate GN2 distribution groove 23, which are defined by a hanging wall 21 and can freely communicate with the outer peripheral side end of the radial distribution groove 13 passing through the groove 2, are bored inside so as to freely communicate with each other in the lower part. At the same time, a semicircular arc-shaped arc-extinguishing seat surface 24 that matches the pocket P of the turret 12 is formed, and the arc-extinguishing seat surface 24
Then, a large number of upper long window holes 25 and lower GN2 injection ports 26 are drilled in two stages, upper and lower, at corresponding positions sandwiching the can mouth β' height position of the can body β, and furthermore, in the upper long window holes 25. Facing hanging wall 21
Trapezoidal GN is formed by installing internal GN2 injection ports 27 in a row horizontally on the surface.
The two distribution slots 22 and the upper parts of the arcuate GN2 distribution slots 23 are also communicated with each other so as to allow ventilation.

On the other hand, the fan-shaped valve port 2 of the rotary valve 28 is in close contact with the upper surface of the wear plate 15 which rotates integrally with the turret 12.
8a as shown in FIGS. 3 and 6, the axes of the turret and 12 are located from the position where the locus of motion of the can body β carried by the can supply conveyor device A and the locus of motion of the can lid α carried by the turret 12 overlap. The opening is made at a return angle of 45 degrees going back to the center, and a spraying area θ (spraying start point θ1 and spraying end point θ2) is provided from just before the can lid α and can body β approach until they are placed. The air blowing ports 15a of the wear plate 15 that rotates can freely coincide with each other when passing through the region θ.

A pressure ring 29 that constantly presses the rotary valve 28 against the wear plate 15, and a compression coil spring 30 that presses the pressure ring 29 downward.
are built into the gas manifold housing 31, and at the same time O-rings 32°3 are installed on the inner and outer peripheries of the rotary valve 28.
3 is fitted to further maintain airtightness.

The GN2 supply into the gas manifold housing 31 is connected from a GN2 supply source (not shown) through a GN2 supply pipe 34 to a supply port 31a opened on the lateral side of the outer circumferential wall of the housing 31, and furthermore, GN2 is connected to the pressure Ring 29 outside and rotary valve 28 sector valve port 2
The spraying of the wear plate 15 that passes through 8a and matches the fan-shaped valve port 28a sends GN2 only to the air supply port 15a that is passing through the region θ, and then flows through the radial distribution slot 13 and the fan-shaped nozzle block N according to the arrow in FIG. , the internal GN2 injection port 2 via the lower GN2 injection port 26 and the upper long window hole 25 of B1.
GN2 spraying work will be carried out from 7 onwards.

Next, as shown in FIG. 3, the seaming device C performs GN2 spraying and seaming as the feeding claws 4 of the can body supply conveyor device A and the pockets P of the can lid feed turret device B rotate in synchronism. The can lid α and the can body β are received by the pot 35 of the seaming device C, and the top and bottom are removed by the lifter L and seaming chucks S and C shown in FIGS. 2 and 4, as in the conventional case. Seaming roll S while being supported
, R, and the resulting group of canned goods δ is rotated counterclockwise and delivered to the next discharge turret device.

Next, the discharge turret device rotates in synchronization with the seaming device C to receive the group of canned goods δ in the pocket 36 as shown in FIG. can guide 3
It is sandwiched between 7a and 37b and discharged to the next process.

The can lid feed device Y that supplies the can lid α to the can lid feed turret device B is equipped with a timing proximity switch S2 as shown in FIG.
When the can lid α reaches the waiting range ε, the protrusion Ta of the timing cam T which rotates synchronously is detected, and the timing is adjusted and set in advance so that the can lid α is supplied.

Thus, in the device Z of the present invention, the can body β onto which LN2 has been dropped and the can lid α, which is sprayed with GN2 and conveyed, approach each other and are passed to the seaming device C.
GN2 is sprayed continuously without interruption, and is injected in a stable flux form over two stages, upper and lower, so it does not excite the density of GN2, and it is powerfully and smoothly sprayed into the can β without creating a turbulent flow state. Since the spray can also be applied to the head space, the O2 in the head space inside the can body β can be expelled to the maximum extent, and effective GN2 replacement can be performed.As a result, the initially filled oxygen in the head space inside the sealed container Since the amount is as small as possible, various adverse effects caused by enclosed oxygen are eliminated.

In addition, the amount of GN2 that is vaporized is forcibly vaporized by the GN2 spraying, thereby creating a gas flow effect and producing high-quality canned goods having a uniform predetermined internal pressure.

By the way, the conventional case of spraying only GN2 and the case of LN2
The experimental results for the case of dripping alone and the case of the present invention are shown in the table below.

However, the control refers to a conventional vacuum pack, and Q and P refer to the nozzle block N in the pocket P of the turret 12.
GN2 blowing from B1, S is the nozzle block N in the inlet area Za of the nitrogen filling device Z, B2. GN2 injection from N and B3, measured values are average values.

From the above table, it can be seen that the combined use of LN2 addition and GN2 injection reduces the amount of enclosed oxygen and appropriately increases the internal pressure of the can, contributing to the reduction of the plate thickness.

In addition, it can be used as a hot pack even when the contents are in a cold pack with a liquid temperature of 22°C.

I am getting the same results as Tsuku. It was 0.23mm at most, but it was 0.17mm for three-piece cans and Q.17mm for two-piece cans. l
It has been confirmed that safety can be guaranteed even when the concentration is reduced to rnm, showing excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a process schematic diagram showing step-by-step the seaming procedure using the conventional drip addition method, and Fig. 2 is a step-by-step process diagram showing the procedure for manufacturing a can containing liquid nitrogen according to the first embodiment of the present invention. FIG. 3 is a plan view showing the structure of the apparatus of the present invention and the flow of can lids and can bodies, and FIG. 4 is a step-by-step diagram showing the working procedure of the method for producing canned goods containing liquid nitrogen according to the second embodiment of the present invention. Fig. 5 is a front view showing a section of the left half of the can lid feed turret device having pockets divided into 10 parts, with a part omitted, and Fig. 6 is the right half of Fig. 5. FIG. A: Can body supply conveyor device, B: Can lid feed turret device, C: Seaming device, D: Discharge turret device, Y: Can lid supply device,
Z...Nitrogen filling device, LN2...Liquid nitrogen, GN2
...Nitrogen gas, O2...Oxygen, H. S...head space, L...lifter, N. B1-N. B3...
・Nozzle block, P... pocket, S. C... seaming chuck, S. R... seaming round, X
...Contents, y...Dripping nozzle, α...Can lid, β
... Can body, γ... Gap, δ... Canned food, θ... Area for spraying, 4... Feed claw, 12... Turret, 2
5... Upper long window hole, 26... Lower GN2 injection port, 2
7... Internal GN2 injection port, 28... Rotary valve, 28a... Fan-shaped valve port, 31... Gas manifold housing.

Claims (1)

[Scope of Claims] 1. A can body filled with contents in a filling process is filled with liquid nitrogen during the transition from the filling process to a seaming process in which the can lid is double-sealed to the can mouth. After being dropped into the body, immediately before the can lid is placed on the can mouth in an area where the transportation trajectory of the can body and the transportation trajectory of the can lid overlap, from the outside of the can lid and can mouth. After blowing nitrogen gas and expelling the oxygen around the can lid and the upper part of the can body to the outside of the can body by the synergistic action of the nitrogen gas and the liquid nitrogen, the nitrogen gas is replaced under the sealed nitrogen gas atmosphere. A method for producing canned goods containing liquid nitrogen, which are subjected to double-wrapping and rut-sealing treatment. 2. The region where the transport movement locus of the can and the transport movement locus of the can lid overlap is the period from the time just before the can lid is placed on the can mouth until the time when the can lid is double-wound and sealed on the can mouth. A method for producing a can containing liquid nitrogen according to claim 1, which comprises: 3. A can body supply conveyor device in which a nozzle for dripping liquid nitrogen hangs down from a predetermined upper side, and a can lid feed turret that holds a can lid placed on the mouth of a can body, and is aligned with each pocket seating surface of the can body, and The rotation angle of the can lid feed turret extends from just before the can lid, which is swivelally conveyed by the can lid feed turret, approaches the mouth of the can body that is transported straight by the can body supply conveyor device until it is placed on the can lid. Spraying is a method of filling nitrogen into cans containing liquid nitrogen, which consists of a can lid feed turret device that has a large number of nitrogen gas injection ports that inject nitrogen gas when it reaches the area.