JPH10337254A - Heating method and device for can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heating efficiency when a content liquid is warmed by a device to heat it from the can bottom suck as a can warmer by arranging a heat transfer plate having a heat transfer part to be in contact with a recessed place of a bottom part of a can body in a can bottom part, and conducting heat to a can from the heat transfer plate and a grounding part on the bottom peripheral edge by mounting it on a heating plate. SOLUTION: In a two-piece can body 1 by molding a steel plate coated with resin, a cover 4 formed of an aluminum plate material is fixed by winding fastening 3. A grounding part 5 on the bottom part peripheral edge of the two- piece can body 1 forms a recessed bottom sink, but a heat transfer plate 6 is arranged to transmit heat by contact with both this bottom part recessed part and a heating plate. In this case, when a pressure sensitive adhesive double coated tape or the like is stuck to the heat transfer plate 6, it stick to the bottom of a can, and handling is facilitated, and it can be freely mounted/ demounted, and can be reused. The heat transfer plate 6 is desirably formed so that a heat transfer part has the area not less than 10% of a recessed place of a can body bottom part and a thickness becomes almost equal to a depth of the recessed place or larger than that.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for heating a can for efficiently heating the can.

[0002]

2. Description of the Related Art A can body made of a metal plate material has a body integrally formed with a bottom at the bottom and a two-piece can body with a separately formed lid, a separately formed bottom lid, an upper lid, and a body. There are two types of three-piece cans. The two-piece can body is a can formed by forming a body having a bottom by drawing and ironing a cup formed from a metal plate, and winding a separately formed lid around the body. On the other hand, the three-piece can body is composed of an upper lid body and a bottom lid body separately formed from a body cylindrical body molded from a metal plate material. The bottom lid body is wound around the lower end of the body cylindrical body so as to have a bottomed body. The can is a device in which an upper lid is wound around an upper opening. When heating the contents at the time of sale, these cans are placed on a heating plate at a store and heated. Usually, it is heated by a shelf with a plurality of heating plates called can warmers, and the heating plate is inclined to the front side, and when the can is taken, the can is moved to the front side and it is formed so that it can be easily removed. ing.
Therefore, the can was heated from the bottom.

[0003]

When a can is heated by a heating plate, there is a problem that it takes a long time to raise the temperature to an appropriate temperature. Does not contain gas in a two-piece can,
In order to improve the pressure resistance, the negative pressure can containing the content to be heated has a convex bottom at the center, and the bottom sink has a depth of 2.5 to 3.5 mm. There are few grounding parts. The countersink has a depth of 5 mm to 8 mm because the 3-piece can also has a tightened portion between the body end and the bottom lid,
The grounding part is small. For this reason, heating from the bottom required a long time. The present invention provides a method and apparatus for heating a can that solves such a problem.

[0004]

According to the present invention, there is provided a heat transfer plate having a heat transfer portion in contact with a recess at the bottom of a can body, placed on the bottom of the can, and placed on a heating plate to transfer the heat. 1. A method for heating a can, characterized in that heat is conducted to the can from the hot plate and the grounding portion at the bottom edge 2. The heat transfer portion of the heat transfer plate has substantially the same shape as the recess at the bottom of the can body, 2. The method for heating a can according to item 1, wherein the thickness is substantially equal to or greater than the depth of the recess 3. The heat transfer portion of the heat transfer plate covers an area of 10% or more of the recess at the bottom of the can body. 3. The method for heating a can according to item 1, wherein the heat transfer plate has a thickness substantially equal to or greater than the depth of the recess 4. The heat transfer plate is a plate formed of a single metal plate. 4. The method for heating a can according to any one of items 1 to 3. 5. The heat transfer plate according to any one of items 1 to 3, wherein the heat transfer plate is a plate formed of a plurality of divided metal plates. Or 1 5. The method for heating a can according to any one of Items 1 to 3, wherein the heat transfer plate is a plate formed by stacking a plurality of metal plates. 7. The method for heating a can according to any one of Items 1 to 6, wherein the heat transfer plate is stuck to the bottom of the can in an easily peeled state. 8. A method for heating a can, characterized in that a bottomed heating cylinder having substantially the same inner diameter as that of the above is fitted to the bottom of the can body, placed on a heating plate, and heated from the bottom peripheral edge and side surfaces. 9. The method for heating a can according to item 8, wherein the cylinder is a cylinder having a donut-shaped bottom provided with a common hole in the center of the bottom at the top and bottom. 10. The method for heating a can according to item 8, wherein the can is a cylinder having a groove in which the grounding portion is fitted and a protrusion protruding from a center of the groove to be in contact with the bottom of the can body. A cylinder in which a hot cylinder is provided with a convex portion having substantially the same shape and thickness as the bottom recess of the can body at the bottom of the cylinder, and a groove is formed between the convex portion and the peripheral wall of the cylinder to fit the ground portion of the can body. 9. The method for heating a can according to item 8. 12. A heating disk having substantially the same shape and thickness as the recess at the bottom of the can is placed on the bottom of the heating cylinder, and the can is placed on the cylinder. 12. A method for heating a can, characterized in that the bottom is inserted, a heating disk is fitted into a recess in the bottom of the can, and the heating cylinder is heated by a heating plate. 13. A heating device consisting of a heat conductor inserted into the recess, which is fitted into the recess at the bottom of the can and conducts the heat of the heating plate to the can 14. Almost the same as the body of the can placed on the heating plate Of a heating cylinder consisting of a heating cylinder having a diameter of the can inserted into the bottom of the can to conduct heat from the heating plate from the bottom and body of the can Raising device. 15. A heating cylinder having substantially the same diameter as the body of the can placed on the heating plate, a recess having a substantially same shape as the recess at the bottom of the can disposed at the bottom of the heating cylinder, and a thickness equal to the depth of the recess. A heating device comprising a heating disc having a bottom inserted into a heating cylinder and conducting heat from a heating plate to the can. "
About.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Practical cans include:
There are two-piece and three-piece cans. For a two-piece can, the body and bottom are formed from a single metal plate to improve pressure resistance.
The bottom is convex inside the can and the periphery of the bottom is a ground contact.
For this reason, since there is a recess that does not touch the bottom of the can body, the contact area is small. On the other hand, in the three-piece can body, the bottom lid, the trunk, and the upper lid are separately formed, and the lower end of the trunk and the bottom lid are tightened to form the bottom. Since this winding portion projects below the bottom and serves as a grounding portion, there is a recess at the bottom of the three-piece can body that does not touch the ground. Further, since a resin serving as a packing is arranged in the tightening portion, it serves as a heat insulating material, and prevents conduction from the tightening portion to the body. For this reason, even if all the conventional cans are placed on the heating plate, heat conduction is small, so that a long time is required for heating.

The present invention improves the heat conduction from a heating plate to a can body and heats in a short time. Since the heat transfer plate used in the present invention needs to be in close contact with the bottom plate of the can body,
It is preferable that the shape is substantially the same as the shape of the recess at the bottom of the can body from the viewpoint of increasing the heat transfer area, and it is advantageous in terms of effect that the thickness is the same as the depth of the recess. Since many of the recesses at the bottom of the can are circular, it is preferable to be disk-shaped. Regardless, it doesn't matter if it is square or triangular. A heat transfer plate smaller than the recess in the can bottom can be used, but the heat transfer effect is reduced. The thickness of the heat transfer plate may be thicker than the depth of the recess at the bottom of the can, but if it is thick and small, the stability of the can body will be poor. The heat transfer plate is formed of a metal plate having good heat conductivity, but an aluminum plate or a copper plate is preferable, and a synthetic resin plate material plated with aluminum, copper, silver, or the like can also be used.

[0007] The heat transfer plate may be a single metal plate, or a plurality of plates may be used in piles. Moreover, you may use combining the thing divided | segmented into two or more. Attachment of the heat transfer plate to the bottom recess of the can body at the time of heating using a pressure-sensitive adhesive or the like in an easily peeling state, and peeling after heating has an advantage that handling at a store is easy. Providing a vertically penetrating hole in the center of the heat transfer plate reduces the contact area, but has the effect of effectively absorbing radiant heat from the heating plate.

[0008] The present invention includes inserting a can into this cylindrical state using a bottomed cylindrical state that opens vertically instead of a single heat transfer plate in order to conduct heat to the can body. The cylindrical shape with the bottom is effective for transferring heat to the bottom and the body of the can. Accordingly, the inner diameter of the cylinder is preferably substantially the same as the diameter of the can body. If the inner diameter is too large, a gap is formed between the inner diameter of the can and the heat transfer effect is deteriorated. The bottom of the heating cylinder may be provided with a hole penetrating downward, and if it is made into a donut shape with a circular through hole in the center of the bottom, the contact area with the heating plate will be small, but radiant heat from the heating plate will not be dissipated Therefore, the absorption becomes good. Further, a groove is provided along the peripheral wall of the cylinder to fit the circular can contact portion, and a projection having a shape and thickness substantially the same as the recess at the bottom of the can body, which is in contact with the bottom of the can body at the center side of the groove. Is formed, heat can be conducted from the heating plate to the bottom of the can body, so that the heating efficiency is significantly improved.

Instead of forming a projection on the bottom of the heating cylinder, a heating disc having substantially the same shape and thickness as the recess at the bottom of the can is placed, and a can body is placed between the disc and the peripheral wall of the cylinder. The same effect can be obtained by forming a groove for fitting the ground portion. The heating cylinder and the heating disk can be formed of the same metal as the above-described heat transfer plate. Further, the present invention provides a method for heating a can, which is used in such a method for heating a can, comprising a heat transfer plate having a shape and thickness substantially the same as those of a recess inserted into the bottom of a can body placed on a heating plate. Apparatus, a heating device for a can composed of a heating cylinder having substantially the same diameter as the body of the can placed on the heating plate, and a recess at the bottom of the can at the bottom of the heating cylinder placed on the heating plate Provision of a protrusion having the same shape and thickness, a heating device for a can in which a groove is provided between the protrusion and the cylindrical peripheral wall to be fitted with the grounding portion of the can body, almost the same as a can body portion mounted on a heating plate A heating cylinder having the same diameter and the same shape and thickness as the recess at the bottom of the can is placed on the heating cylinder having the same diameter and the bottom of the heating cylinder disposed at the bottom of the heating cylinder. The present invention also relates to a can heating device in which a groove is provided between peripheral walls to be fitted with a ground portion of a can body. All of these heating devices are used, for example, when heating cans with a can warmer at a store, but any of them can be used repeatedly.

[0010]

Next, the present invention will be specifically described with reference to examples.

FIG. 1 shows an embodiment of the present invention for heating a two-piece can body. Reference numeral 1 denotes a two-piece can formed by molding a steel plate coated with a resin. Reference numeral 4 denotes a lid formed of an aluminum plate material. 5 is 2
It is a ground contact portion at the periphery of the bottom of the piece can body and forms a concave bottom sink, but has a line contact with a heating plate (not shown) and has a very small contact area. Reference numeral 6 denotes a heat transfer plate used in the present invention, which is a flat plate in this embodiment. The heat transfer plate 6 contacts both the bottom recess of the can and the heating plate to transfer heat. The heat transfer plate may contact the grounding part 5,
When the can is placed on the heating plate, it can be inserted into the bottom of the can and placed. When a double-sided adhesive tape or the like is stuck to the heat transfer plate, it is stuck to the bottom of the can for easy handling, and can be reused by making it detachable, so that it is easy to use.

FIG. 2 shows another embodiment in which a ring-shaped heat transfer plate 6 is used. If a ring-shaped heat transfer plate concentric with the bottom of the can and smaller than the bottom diameter of the can is used, the heat transfer area by conduction increases, and heat is transferred by convection and radiation of air in the space 7 at the center of the ring. . Thus, a through hole may be provided in the heat transfer plate.

FIG. 3 shows another embodiment in which a square heat transfer plate 6 smaller than the bottom diameter of the can is used.

FIG. 4 shows another embodiment of the two-piece can body.
1 is a two-piece can formed of an aluminum plate,
Is a lid made of the same material, which is tightly wound at 3. Reference numeral 5 denotes a bottom grounding portion, and a dome-shaped recess 2
Are formed. Reference numeral 6 denotes a heat transfer plate used in the present invention, which in this embodiment is a spherical heat transfer plate that comes into contact with the surface of the bottom concave portion.

FIG. 5 shows an embodiment of the present invention for heating a three-piece can body. Reference numeral 1 denotes a body formed from a steel plate;
Is a top cover made of aluminum, 8 is a bottom cover made of steel, and is tightly wound at 3, 3 '. A ground portion is formed by the bottom lid 3 ', and a bottom recess is present. Reference numeral 6 denotes a heat transfer plate in contact with the bottom, which is a flat plate.

FIG. 6 shows another embodiment of the three-piece can body, in which a ring-shaped heat transfer plate 7 having a diameter smaller than the diameter of the bottom of the can and concentric with the bottom of the can is used.

FIG. 7 shows another embodiment of the three-piece can body, in which a circular heat transfer plate 6 having a heat transfer portion 8 in contact with a bottom smaller than the diameter of the can bottom and having a diameter substantially the same as the outer diameter of the can. This is an example using.

FIG. 8 shows another embodiment of the present invention.
An example used for a three-piece can is shown. The heat transfer plate 6 is a bottomed cylinder having an inner diameter substantially the same as the outer diameter of the can, and the inner diameter portion comes into contact with the body of the can and the outer surface of the tightened portion 3 '.

In FIG. 9, a protrusion smaller than the diameter of the bottom is formed at the center of the heat transfer body, so that heat conduction from the bottom is increased. The protrusion of the heat transfer body may be formed separately from the heat transfer plate and may be combined with the heat transfer plate, or may have a size that comes into contact with the tightened portion.

In FIG. 10, a heat transfer plate in which a through hole 9 is formed at the center of the heat transfer body 6 is used, and radiation from the heating plate is efficiently absorbed. Of course, the heat transfer bodies of FIGS. 8 to 10 can be used for a two-piece can body.

Example 1 A can body shown in FIG. 1 is a TF laminated film.
This is a two-piece can body formed by deep drawing a thin sheet of S, and the grounding portion at the bottom of the can is a line contact grounding portion. The bottom sink is 2.8 mm, the outer diameter of the can is 52.5 mm, and the height of the can is 104.5 mm. The bottom diameter of the can bottom is 46.1m
m, and the diameter of the flat portion of the bottom recess is 41 mm.
The contact width is about 0.2 mm. The heat transfer plate is a flat disk made of aluminum, having a diameter of 40.5 mm and a thickness of 3 mm. The contact area of the heat transfer plate is 97.
6%.

Embodiment 2 This is an example using the heat transfer plate shown in FIG. 2, and the heat transfer plate has an outer diameter of 35 mm and an inner diameter of 17 mm. Other than that is the same as the first embodiment. The contact area of the heat transfer plate is 55.7% of the area of the bottom recess.

Embodiment 3 This is an example using the heat transfer plate shown in FIG. 3, and the shape of the heat transfer plate is a square having a side of 25 mm. Otherwise, Example 1
Is the same as The contact area of the heat transfer plate is 47.
3%.

Embodiment 4 This is an example using the heat transfer plate shown in FIG. 1, and the heat transfer plate has an outer diameter of 20 mm. Other than that is the same as the first embodiment. The contact area of the heat transfer plate is 23.8% of the area of the bottom recess.

Example 5 The can body shown in FIG. 4 is a two-piece can body obtained by drawing and ironing a thin aluminum plate, and is a can with a lid wound around. The diameter of the bottom contact part is 42 mm. A dome-shaped recess is formed inside the ground portion. The outer diameter of the can is 53.5m
m and the height of the can is 105 mm. The heat transfer plate has a curved surface that comes into contact with the surface of the dome-shaped recess, the surface that comes into contact with the heating plate is flat, and its diameter is 4 mm.
1 mm. The contact area of the heating plate contact surface of the heat transfer plate is 95.3% of the bottom recess area.

Example 6 The can body shown in FIG. 5 was composed of an upper lid formed of an aluminum plate, a bottom lid formed of a TFS plate, and a can body formed by bonding a TFS thin plate into a cylindrical shape. This is a three-piece can body that has been tightly wound, wherein the tightly wound portion of the bottom lid is a grounding portion and forms a bottom recess. The countersink is 4.1 mm, the ground diameter is 51 mm, and the ground width is about 0.2 mm. The outer diameter of the can is 53 mm and the height of the can is 104 mm. The inner diameter of the bottom recess is 49 mm, while the diameter of the flat part is 42.5 mm. The heat transfer plate is a flat disk made of aluminum, having a diameter of 48 mm and a thickness of 5 mm. The contact area of the heat transfer plate is 100% of the area of the bottom recess.

Embodiment 7 This is an example in which the heat transfer plate shown in FIG. 6 is used. The heat transfer plate has an outer diameter of 35 mm and an inner diameter of 17 mm. Other than that is the same as the sixth embodiment. The contact area of the heat transfer plate is 51.8% of the area of the bottom recess.

Embodiment 8 This is an example in which the heat transfer plate shown in FIG. 7 is used. The heat transfer plate has an outer diameter of 40 mm and an outer diameter of 53 m.
m. The thickness of the heat transfer plate is 6 mm. Other than that is the same as the sixth embodiment.

Embodiment 9 This is an example in which the heat transfer plate shown in FIG. 8 is used. The heat transfer plate has an outer diameter of 57 mm and an inner diameter of 53 mm.
The height of the heat transfer plate is 15 mm. The bottom of the heat transfer plate has a thickness of 2 mm. Other than that is the same as the sixth embodiment.

Embodiment 10 This is an example in which the heat transfer plate shown in FIG. 9 is used. In the heat transfer plate, the shape of the heat transfer plate of the ninth embodiment has a protrusion at the center, and the outer diameter of the protrusion is 38 mm. The height of the heat transfer plate is 15 mm.
Other than that is the same as the sixth embodiment.

Embodiment 11 This is an example in which the heat transfer plate shown in FIG. 10 is used. The shape of the heat transfer plate in the ninth embodiment has a through hole at the center, and the diameter of the through hole is 42 mm. The height of the heat transfer plate is 15 mm. Other than that is the same as the sixth embodiment.

COMPARATIVE EXAMPLE 1 A two-piece can body obtained by deep-drawing a thin TFS sheet laminated with a film, only the can body portion shown in FIG. 1, and the grounding portion at the bottom of the can is a line contact grounding portion. ing. The bottom sink is 2.8mm and the height of the can is 105mm
It is. The ground diameter of the can bottom is 46.1 mm, and the diameter of the flat portion of the bottom recess is 41 mm. The contact width is about 0.2mm
It is.

Comparative Example 2 Only the can body portion shown in FIG. 4 was a two-piece can body obtained by squeezing and ironing an aluminum thin plate, which was a can with a lid wound around. The diameter of the bottom contact part is 42 mm. A dome-shaped recess is formed inside the ground portion. The outer diameter of the can is 53.5 mm and the height of the can is 105 mm.
The contact width is about 0.2 mm.

Comparative Example 3 Only the can body portion shown in FIG. 5 was composed of an upper cover formed of an aluminum plate, a bottom cover formed of a TFS plate, and a can body obtained by bonding a TFS thin plate to a cylindrical shape and bonding the same. This is a three-piece can body in which the lids are wound around each other, wherein the bottom lid is fastened by a grounding portion to form a bottom recess. The countersink is 4.1 mm, the ground diameter is 51 mm, and the ground width is about 0.2 mm. The outer diameter of the can is 53m
m and the height of the can is 104 mm.

Comparative Test 10 cans of each of the cans of the embodiment and the comparative example in which the same amount of liquid (using water) was filled in a heating plate set at 70 ° C. to 90 ° C. surrounded by a cardboard box, and The process of temperature rise of the content liquid at almost the middle point in the can was measured with a thermocouple. Evaluation method Measure the temperature rise of the content liquid of each can type by a comparative test,
The elapsed time (seconds) was measured from 15 ° C. to 55 ° C.
Further, a shortening rate ((T0−Tn) / T0 * 100%) of the heating time Tn of the example with respect to the heating time T0 of the comparative example was determined. The effect of improving the heating efficiency increases as the heating time is shorter and the rate of shortening the heating time is larger. Table 1 shows the measurement results.

[0036]

[Table 1]

(Note) Elapsed time of temperature rise is 15 ° C.
From 55 ° C to 55 ° C. The heating rate reduction rate is a reduction rate of the heating time Tn of the example to the heating time T0 of the comparative example, and is represented by (T0−Tn) / T0 * 100%. Example 5 was compared with Comparative Example 2, and Examples 6 to 11 were compared with Comparative Example 3. It can be seen that in all the examples, the temperature raising shortening rate reached from 4% to slightly more than 50%.

[0038]

According to the present invention, the effect of improving the heating efficiency is obtained by arranging a heat transfer plate in the concave portion of the can bottom to heat the content liquid with a device that heats from the can bottom, such as a can warmer. You.

[Brief description of the drawings]

FIG. 1 is a diagram in which a disc-shaped heat transfer plate is arranged in a bottom concave portion of a two-piece can body.

FIG. 2 is a diagram in which a ring-shaped heat transfer plate is arranged in a bottom concave portion of a two-piece can body.

FIG. 3 is a view in which a small-diameter disc-shaped heat transfer plate is arranged in a bottom concave portion of a two-piece can body.

FIG. 4 is a view in which a heat transfer plate having substantially the same shape as the concave shape is arranged in the bottom concave portion of the two-piece can body.

FIG. 5 is a view in which a disk-shaped heat transfer plate is arranged in a bottom recess of a three-piece can body.

FIG. 6 is a diagram in which a ring-shaped heat transfer plate is arranged in a bottom recess of a three-piece can body.

FIG. 7 is a view in which a heat transfer plate provided with a projection at the center in the bottom concave portion of the three-piece can body is arranged.

FIG. 8 is a view in which a bottomed cylindrical heat transfer plate is arranged in a bottom recess of a three-piece can body.

FIG. 9 is a view in which a bottomed cylindrical heat transfer plate having a projection at the center is disposed in the bottom recess of the three-piece can body.

FIG. 10 is a diagram in which a bottomed cylindrical heat transfer plate having a through hole in the center in the bottom recess of the three-piece can body is arranged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Can body 2 Domed concave part 3 Winding part 4 Polyhydric alcohol 5 Grounding part 6 Heat transfer plate 7 Heat transfer plate space 8 Bottom lid 9 Through hole

Claims (15)

[Claims] 1. A heat transfer plate having a heat transfer portion in contact with a recess at the bottom of a can body is arranged on the bottom of the can, and is placed on a heating plate to transfer heat from the heat transfer plate and a grounding portion on the bottom periphery. A method for heating a can, characterized in that the heat is conducted to the can. 2. The can according to claim 1, wherein the heat transfer portion of the heat transfer plate has substantially the same shape as the recess at the bottom of the can body, and has a thickness substantially equal to or greater than the depth of the recess. Heating method. 3. The heat transfer portion of the heat transfer plate has a recess at the bottom of the can body.
The method for heating a can according to claim 1, wherein the can has an area of not less than% and a thickness is substantially equal to or greater than a depth of the recess. 4. The method for heating a can according to claim 1, wherein the heat transfer plate is a plate formed of a single metal plate. 5. The method for heating a can according to claim 1, wherein the heat transfer plate is a plate formed of a plurality of divided metal plates. 6. The method for heating a can according to claim 1, wherein the heat transfer plate is a plate formed by stacking a plurality of metal plates. 7. The method for heating a can according to claim 1, wherein the heat transfer plate is attached to the bottom of the can in an easily peeled state. 8. A bottomed heating cylinder having an inner diameter substantially the same as the diameter of the body of the can is fitted to the bottom of the can, placed on a heating plate, and heated from the bottom peripheral edge and side surfaces. How to heat the can. 9. The heating cylinder according to claim 8, wherein the heating cylinder is a cylinder having a donut-shaped bottom provided with a common hole at the center of the bottom.
The method for heating a can described in 1. 10. The heating cylinder according to claim 8, wherein the heating cylinder is a cylinder having a groove which fits the ground portion of the circular can body along the side wall and a projection which is in contact with the bottom of the can body at a center side of the groove. How to heat the can. 11. A heating cylinder provided with a convex portion having substantially the same shape and thickness as a bottom concave portion of a can body at the bottom of the cylinder, and a ground portion of the can body is fitted between the convex portion and a cylindrical peripheral wall. The method for heating a can according to claim 8, wherein the can is a cylinder having a groove. 12. A heating disc having substantially the same shape and thickness as the recess at the bottom of the can body is placed on the bottom of the heating cylinder, and the bottom of the can body is inserted into the cylinder to remove the heating disc from the recess at the bottom of the can. A heating method for a can, wherein the heating cylinder is fitted to a place and the heating cylinder is heated by a heating plate. 13. A heating device, comprising a heat conductor inserted into a recess at the bottom of a can placed on a heating plate, and fitted in the recess at the bottom of the can to conduct heat from the heating plate to the can. 14. A heating cylinder comprising a heating cylinder having substantially the same diameter as the body of the can placed on the heating plate, wherein the bottom of the can is inserted and heat of the heating plate is conducted from the bottom and the body of the can. Heating device for cans. 15. A heating cylinder having substantially the same diameter as the body of the can placed on the heating plate, a shape substantially the same as a recess at the bottom of the can disposed at the bottom of the heating cylinder, and a depth of the recess. A heating device comprising a heating disk having the same thickness as that of the above, wherein the bottom of the can is inserted into a heating cylinder to conduct heat of the heating plate to the can.