JPH11290965A - Iron core forming method, and die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an iron core binding method by the laser beam welding and a die capable of obtaining high welding strength without increasing the welding energy in the die. SOLUTION: A punched sheet 8 is successively laminated in a die (a lower die 1), a punching oil is removed by spraying a drying gas 10a in the direction of lamination around four welded points A-D in the circumferential direction of the laminated sheets 8, the laser beam irradiation is achieved to start the welding between the sheets 8 in the direction of lamination from one welded point A in the circumferential direction among the four welded points A-D in a condition where a shield gas flows in the direction of lamination of the sheets 8 from a forward part to a rear part of the welded points A-D, and the welding between one or a plurality of sheets is achieved from the welded point B different from the one welded point A or other welded points C, D in the direction of lamination to bind the iron core in the die (the lower die 1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an iron core by successively aligning and laminating thin sheets formed by continuously punching a strip-shaped core material with a mold in the mold, and then welding and laminating the laminated thin sheets. Regarding the mold.

[0002]

2. Description of the Related Art As an example of a method for forming an iron core by laminating thin plates, a strip is formed by continuously punching a strip-shaped core material with a die, and a projection is provided in a back portion of the thin plate so as to be punched before the thin plate. Further, there is an iron core formed by press-fitting the projections of the thin plate into the recesses on the back side of the projections of the front thin plate and binding them. This projection-type iron core has a gap formed between adjacent thin plates when the projections are pressed into the recesses and bound, so the magnetic characteristics of the iron core are poor and many iron plates are laminated to improve the characteristics. , In the direction of larger weight. For this reason, recently, there has been developed an iron core formed by abolishing protrusions and laminating thin plates without gaps by laser welding in a mold and automatically binding them.

When a thin plate is automatically bound in this mold, a predetermined number of the thin plates are stacked and bound to form an iron core, so that separation is required every predetermined number of sheets. . In order to ensure separation, the spot diameter of laser welding needs to be suppressed to about twice the plate thickness, and the welding energy is limited (upper limit).
Further, in order to improve the magnetic properties of the iron core, it is important to minimize the thermal distortion of welding. For these reasons, it is desirable that the welding energy be small. For the above reasons, welding is performed with a welding energy per point of about 15 J or less.

When welding is performed in a mold with the above energy, the welding tensile strength per point is 30 to 70 N.
For this reason, depending on the number of welding points per iron core, an upper limit is imposed on the product (core) weight in order to obtain normal reliability of thin plate binding, and one product (iron core) bound in a mold is required. ) About 1 to 3 kg in weight, laser welding bundling is applied in a mold, and there is no application example for a product weight more than this. And to maintain and maintain the strength of laser welding,
There is a demand for an apparatus structure that can be easily inspected and confirmed in daily production so that the optical axis is displaced due to dirt and damage of the optical system and looseness of the optical parts, thereby preventing a large transmission loss of welding energy. .

[0005]

The following factors can be considered as factors for reducing the laser welding strength in the mold. Blowholes occur in the welding due to the adhesion of the punching oil to the welding surface. The base metal which instantaneously melts the fumes generated during welding and the carbon contained in the punching oil is entrained and solidified.

[0006] The heat of welding causes the thin plate to expand and receive compressive stress in the mold, causing cracks in the weld. Due to the thickness deviation of the base material, the welding of the seam of the adjacent thin plate is shifted, and the joint strength of the seam is reduced.

In order to increase the laser welding strength of the iron core, it is preferable that the punched thin plates are laminated in a mold and welding is performed outside the mold.
A weld tensile strength of 40N is obtained. However, welding outside the mold requires additional equipment, and the entire equipment becomes larger.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and a mold for forming a core of a core by laser welding capable of obtaining high welding strength without increasing welding energy in the mold. And

[0009]

The mold according to the present invention is
2. The die according to claim 1, wherein the thin plates punched by the upper die and the lower die are laminated in the lower die, and the thin plates are joined by laser welding to form an iron core. A work holding hole penetrated vertically in the center of the lower mold, an oil drying groove formed in a side surface of the lower part of the die of the work holding hole, and a drying gas supplied to the oil drying groove. A plurality of laser irradiation chambers disposed at a substantially central portion in a penetrating direction of the work holding hole so as to penetrate the lower mold body at right angles and open horizontally, and a shielding gas is provided in the laser irradiation chamber. And a thin plate is joined by laser irradiation welding to form an iron core. According to this mold, the punching oil adhering to the welding surface at the time of punching the thin plate is volatilized by the drying gas along each oil drying groove to each welding point, and is blown at each welding point. Since the amount of adhesion is reduced to a level at which no holes are generated, a factor for lowering the welding strength can be removed, and the welding strength can be improved.

According to a second aspect of the present invention, the laser irradiation chamber is provided with a step in the vertical direction of the lower die. If a step is provided, the welding sequence is performed by moving the welding point for each step, so other welding points B to D are not performed in welding at the welding point A, and the thermal expansion due to welding is only the welding point A. . At the welding point B, the welding points C to D are not welded. Like this one
Since the welding is performed only at the portions, the thermal expansion of each thin plate held in the work holding hole is small as compared with the simultaneous welding at four portions, and it is possible to prevent welding cracks due to compressive stress.

In the third aspect, a center hole is formed at the center of the tip of the laser irradiation chamber, and a tip shield is provided at a work holding hole side of the tip of the laser irradiation chamber, and a side shield hole is provided between the tip shield and the lower mold. A shield gas groove is formed by drilling the hole and the inner diameter of the work holding hole, and the shield gas groove communicates with the side shield hole. With this configuration, welding is performed at various welding points in a state where various shielding gases flow during and before and after welding. That is, the pre-weld side shield gas flowing from before the welding scatters fumes and carbon scattered around the upper portions of the respective welding points after the welding and pushes down the fumes and carbon in the downward direction. After welding, the side shield gas, including the fume and carbon, flows the fume and carbon from the shield gas groove to the exhaust pipe via the exhaust flow path. As a result, fumes and carbon are not entangled in the weld bead, and high-strength welding can be obtained.

Further, in the present invention, an exhaust flow path is provided in which a lower die body is connected to a lower end of the shield gas groove from a lower end thereof. Then, when various shielding gases during welding are released into the mold from the respective welding points only by the center shielding gas, if the flow resistance in the mold is large, the gas flow is obstructed, and Fumes and carbon are likely to stay at the welding point, causing entrapment in the weld bead, but this can be prevented because the gas is forcibly discharged from the exhaust flow path to the atmosphere by the exhaust fan. .

According to a fifth aspect of the present invention, one outlet of the exhaust passage is covered with a groove-shaped ring-shaped recovery ring, and a recovery groove is formed by the groove of the recovery ring. In general, the exhausted shielding gas contains many solids such as welding spatter and powdered carbon. The adhesion and accumulation of these solids block the exhaust flow path and impede the flow of the exhaust shield gas, so that fumes and carbon can easily accumulate at the welding point and cause entrapment in the weld bead. ,
Since solid matter can be dropped into the collecting groove and collected, obstruction of gas flow can be prevented.

According to a sixth aspect of the present invention, a storage chamber is provided which is perforated from the vicinity of the outer periphery of the die on the upper end surface of the lower die toward the laser irradiation chamber, and a protective glass is inserted into the storage chamber.
The protective glass can prevent contamination of the optical system due to spatter or fume during laser welding.

According to a seventh aspect of the present invention, there is provided a storage chamber which is perforated from the vicinity of the outer periphery of the die on the upper end surface of the lower die toward the laser irradiation chamber, and a laser output measuring device is inserted into the storage chamber. By exchanging the protective glass holder and the output measuring device in the storage room, the output of the laser can be easily measured, the output measuring operation can be reduced, and the mold structure can be simplified.

According to an eighth aspect of the present invention, there is provided a mold for laminating thin plates punched by an upper die and a lower die in a lower die and joining the thin plates by laser welding to form an iron core. A work holding hole is formed in each of the molds as a divided mold of a mold and a second lower mold, and a die is buried in the center of the first lower mold.
A laser irradiation device is buried and formed inside the second lower mold. The blade part (No. 1
Since the lower part) and the welded part (the second lower mold bed) having a complicated structure can be separated, maintenance work can be reduced. When a thin plate having the same punching outer diameter but a different shape is to be pulled out, only the blade portion (first lower die) can be replaced to cope with it, thereby reducing the die replacement work and simplifying the die structure. It becomes possible.

According to a ninth aspect of the present invention, the optical system constituting the laser irradiation device can be moved up and down. Even when the position of the welding spot is located at the center of the thickness of the thin plate due to the deviation of the thickness of the strip-shaped material and the bonding strength is reduced, the welding screw can be corrected by the adjusting screw to prevent the reduction of the bonding strength. As a result, the minimum value of the bonding strength can be increased, and the strength of the bundled iron core can be increased, so that the application of the laser welding and bundling in the mold can be expanded to a core having a large weight and a large outer diameter.

According to a tenth aspect of the present invention, the punched thin plates are sequentially laminated in a mold, and punching oil is removed by spraying a drying gas in a laminating direction around a plurality of welding points in the circumferential direction of the laminated thin plates. With the shielding gas flowing in the lamination direction from the welding point and before and after to the lamination direction, laser irradiation is performed to laminate the welding between the laminations from one welding point in the circumferential direction among the plurality of welding points. Forming a core in a mold by performing welding in the lamination direction starting from a first welding point and a welding point different from the other welding points in the stacking direction. It is. According to this method, the functions and effects of claims 1 to 6 can be obtained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view showing a lower die punching portion of the mold of the present invention, FIG. 2 is a sectional view of the mold, FIG. 3 is an external view of a welding point, and FIG. 4 is a sectional view at the time of output measurement.

First, description will be made with reference to FIG. 2 showing a schematic overall configuration of a mold. Punch 6 at the bottom of a press device not shown
The lower die 1 is installed below the upper die 5 with a band-shaped core material 4 interposed therebetween. A ring-shaped die 7 is buried at the center of the upper surface (upper die 5 side) of the lower die 1, and a workpiece is held by the inner diameter of the die 7 and a hole penetrated vertically in the center of the lower die 1. A hole 9 is formed. An oil drying groove 10 having a U-shaped cross section is drilled in a ring shape below the die 7 of the work holding hole 9, and the die 7 side has an inflow portion 1.
2, the discharge portion 13 is formed on the side opposite to the die 7. Further, the laser irradiation chamber 1 is located substantially at the center of the workpiece holding hole 9 in the penetration direction.
6 penetrate the lower die 1 body at right angles to the work holding hole 9 and are opened at four positions (two positions are shown in FIG. 2) at 90-degree intervals in the horizontal direction. As shown in FIG. 16
Tip shields 17a and 17b are provided at the tip of the work holding hole 9 side.
Is provided. A center hole 16a is formed between the tip shields 17a and 17b. A side shield hole 17 is drilled between the tip shield 17a and the lower mold 1, and a shield gas groove 19 is drilled between the tip shield 17a and the inner diameter of the work holding hole 9. A gas groove 19 communicates with the side shield hole 17. The shield gas groove 19 communicates with an exhaust passage 18 that penetrates the lower body 1 at its lower end. The four laser irradiation chambers 16A to 16D are formed by providing steps in the upper and lower directions of the lower mold 1. For example, the steps are sequentially provided in the laser irradiation chambers 16A to 16D and the laser irradiation chambers located on a diagonal line are provided. The space between the steps in the chambers 16A and 16C is L dimension.

One outlet of the exhaust passage 18 is covered with a groove-shaped recovery ring 24 to form a recovery groove 25 in the groove of the recovery ring 24, and the other outlet is connected to an exhaust fan 26 through an exhaust pipe 26. 27 and a filter 28. The collecting groove 25 receives and collects spatter and carbon during welding. Then, an inverted L is formed by communicating and piercing from the vicinity of the outer periphery of the die 7 on the upper end surface of the lower mold 1 toward the laser irradiation chambers 16A to 16D.
There is a storage chamber 29 shaped like a letter, in which a protection glass holder 21 with a built-in protection glass 20 is inserted so that the protection glass 20 is arranged in the laser irradiation chambers 16A to 16D. Behind the protective glass 20 in the laser irradiation chambers 16A to 16D, a processing optical lens 22 and an optical fiber emission end 23 are sequentially arranged. When measuring the output of the laser, as shown in FIG. 5, the protective glass holder 21 is taken out of the storage chamber 29, and an output measuring device 30 is inserted instead. The cross-sectional shapes of the output measuring device 30 and the protective glass holder 21 are the same. In addition, protective glass 20
Protects the optical system (the processing optical lens 22 and the optical fiber emission end 23) from spatter and fumes during laser welding.

Next, the positional relationship of the processing optical system 2 incorporating the processing optical lens 22 disposed in the lower mold 1 is shown in FIG.
As shown in the figure, there are four welding points A to D on the outer peripheral portion of the thin plate 8 housed in the work holding hole 9 at the center of the lower die 1.
The processing optical system 2 to which the optical fiber 3 is connected facing each welding point is arranged at 90-degree intervals in the horizontal direction. A die 7 is provided on the outer periphery of the thin plate 8, and one processing optical system 2 is provided.
Gas inlet port 14 and gas outlet port 15
Are arranged respectively.

The shield gas 11 flows into the laser irradiation chamber 16A, and is divided into an upper shield gas 11a and a lower shield gas 11b. Processing optical lens 2
After passing through the protective glass 20 through the second shield gas 2, the upper shield gas 11 a is
a side shield gas before welding 11 d flowing in parallel with the welding surface above welding point A in the shielding gas groove 19 located on the side surface a
And the gas 11c flowing to the center hole 16a. The lower shield gas 11b flows to the center hole 16a without branch flow. Then, the gas 11b,
11c merges into the center shield gas 11bc,
The gas 11bc and the gas 11d merge and flow through the shield gas groove 19 located on the side surface of the side shield 17b in parallel with the welding surface below the welding point A.
1e, the gas is discharged from the shield gas groove 19 to the atmosphere from the exhaust pipe 26 via the exhaust passage. In addition, lower mold 1
Is written larger than the gap between the lower mold 1 and the upper mold 5 in FIG.
Has dimensions that can be taken out.

A method for manufacturing an iron core using the above-configured apparatus will be described. In FIG. 2, a disc-shaped thin plate 8 formed by punching a band-shaped material 4 conveyed by a conveying device (not shown) by a punch 6 and a die 7 is held in a work holding hole 9, and subsequently, the punched thin plate 8 The layers are stacked in the work holding hole 9 while moving downward by the thickness t. When the thin plate 8 comes to the oil drying groove 10, the drying gas 10 a flowing from the inflow portion 12 hits in parallel with the welding surface of the thin plate 8,
During the punching operation, the drying gas 10a is discharged from the discharge unit 13 to the outside of the mold while the attached punching oil is volatilized and scattered.

Subsequently, when reaching the laser irradiation chamber 16A, at the welding point A near the center hole 16a, the side shield gas 11d before welding, the center shield gas 11bc,
In a state where the side shield gas 11e after the welding flows while descending in the laminating direction in parallel with the welding surface, the laser beam emitted from the optical fiber emission end 23 is processed by the processing optical lens 2.
The thin plate 8 is radiated to the welding point A via 2 and welded.

This operation is performed in the order of welding points B, C, and D to form an iron core having four welding points in the circumferential direction in the laminating direction. According to this iron core forming method, the volatilization of the punching oil adhered to the welding surface at the time of punching the thin plate 8 is promoted by the drying gas 10a along the oil drying grooves 10 to the welding points A to D, respectively. At points A to D, the amount of adhesion is reduced to a level at which blowholes are not generated, so that a factor for lowering the welding strength can be removed and the welding strength can be improved.

Next, welding is performed at various welding points A to D during and before and after welding with various shield gases flowing. That is, the pre-weld side shield gas 11d flowing from before the welding scatters fumes and carbon scattered around the upper portions of the welding points A to D after the welding and pushes the fumes and carbon in the downward direction. The post-welding side shield gas 11e is used to cover the fumes and carbon, including the fumes and carbon, with the shield gas grooves 19e.
Through the exhaust passage to the exhaust pipe 26. As a result, fumes and carbon are not entangled in the weld bead, and high-strength welding can be obtained.

If various shield gases during this welding are discharged from the welding points A to D into the mold only by the center shield gas 11bc, the flow of the gas is obstructed when the flow resistance in the mold is large. At the welding points A to D, fumes and carbon are liable to stagnate and become trapped in the welding bead. However, the gas is forcibly discharged from the exhaust passage 18 to the atmosphere by the exhaust fan 27. Can be prevented.

The exhausted shielding gas contains a lot of solids such as welding spatter and powdered carbon. The adhesion and accumulation of these solids block the exhaust flow path 18 and obstruct the flow of the exhaust shield gas, so that fumes and carbon are likely to stay at the welding point, and cause entrapment in the weld bead. However, since the solid can be dropped into the collecting groove 25 and collected, it is possible to prevent gas flow from being hindered.

On the other hand, since the welding sequence is performed by moving to the welding points A to D, in the welding at the welding point A, the other welding points B to
Since D is not performed, the thermal expansion due to welding is only at welding point A. At the welding point B, the welding points C to D are not welded. As described above, since only one spot is welded, the thermal expansion of the thin plate 8 per sheet held in the work holding hole 9 is smaller than that of simultaneous welding at four spots, and cracks in welding due to compressive stress are prevented. Can be. (It should be noted that only the welding point A is used only at the time of start and continuous welding is performed at predetermined locations as the iron core, for example, welding points A to D are welded). Further, the exchange of the protective glass holder 21 and the output measuring device 30 in the storage chamber 29 facilitates laser output measurement,
The output measurement work is reduced, and the mold structure can be simplified.

By the above-described overall action, the welding strength is increased by obtaining 90 to 140 N per point with the same energy as in the past, and it is suitable for an iron core having a large number of laminated thin plates and a large iron core, and an iron core having a large outer diameter of the thin plates. In addition, laser welding can be performed in the mold. Alternatively, if the welding strength is the same as before, the welding energy can be reduced, and energy saving can be achieved. In addition, there is an effect that the maintenance of the welding strength is facilitated and the quality of the welding can be stabilized.

(Second Embodiment) FIGS. 6 to 8 show the second embodiment.
This will be described with reference to FIG. In FIG. 6, the lower mold is the first lower mold 3
2 and the mold bed 31 of the second lower mold are divided into two. The die 7 is embedded in the first lower die 32. Mold bed 31
Is provided with a welding portion 33 at the center thereof, and a laser irradiation chamber 33a is provided inside the welding portion 33. Inside the laser irradiation chamber 33a, a processing optical system 35 having a nozzle 36 at the tip and an optical fiber 37 connected to the rear is provided with a slide groove 3
4 vertically movable. The upper portion of the processing optical system 35 is pressed downward by a spring 39 embedded in the welded portion 33, and the lower portion is pressed and positioned by an adjustment screw 38 to be positioned.

According to this configuration, the blade portion (first lower mold 32), which requires frequent re-grinding maintenance, and the welded portion (second lower mold bed 31) having a complicated structure can be separated from each other. Can be reduced. When a thin plate having the same punching outer diameter but a different shape is to be pulled out, only the blade portion (first lower die 32) can be replaced to cope with it, thereby reducing the die replacement work and simplifying the die structure. Becomes possible.

Further, in the welded portion 33, even when the position of the welding spot 41 is located at the center of the thickness of the thin plate 40 as shown in FIG. Since the vertical position of the processing optical system 35 can be adjusted by the adjusting screw 39 or the adjusting screw 38, the welding spot 41 can be corrected to the position shown in FIG. As a result, the minimum value of the bonding strength can be increased, and the strength of the bundled iron core can be increased, so that the application of the laser welding and bundling in the mold can be expanded to a core having a large weight and a large outer diameter.

[0035]

As described above, according to the present invention, it is possible to obtain a high-strength weld without increasing the welding energy by reducing the factors causing a decrease in welding strength. It can be expanded to large and large diameter cores. Further, in order to maintain and manage high-strength welding, the mold structure can easily check and confirm contamination of the optical system, transmission loss of welding energy and reduction in laser output in daily production.

[Brief description of the drawings]

FIG. 1 is a plan view of a mold (lower mold) showing one embodiment of the present invention;

FIG. 2 is a sectional view of a mold,

FIG. 3 is an enlarged sectional view showing a main part of a lower mold;

FIG. 4 is an external view of a welding point,

FIG. 5 is a cross-sectional view showing a main part of a lower mold at the time of output measurement.

FIG. 6 is a sectional view of an essential part showing a second embodiment of the lower mold;

FIG. 7 is an explanatory diagram of a case where a welding point position is bad,

FIG. 8 is an explanatory diagram of a case where a welding point position is good.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lower mold, 2, 35 ... Processing optical system, 3, 37 ... Optical fiber, 4 ... Strip-shaped iron plate material, 5 ... Upper mold, 6 ... Punch, 7 ... Die, 8 ... Thin plate, 9 ... Work holding hole, 10 ... Oil drying groove, 10a: drying gas, 11: shielding gas, 11a: upper shielding gas, 11b: lower shielding gas, 11d: side shielding gas before welding, 11bc: center shielding gas, 11e: side shielding gas after welding, 12 ... inflow part, 13 ... discharge part, 16, 16A, 16B, 16C, 16D, 33a ... laser irradiation chamber, 16a ... center hole, 17 ... side shield hole, 17a, 17b ... tip shield, 18 ... exhaust flow path, 19 ... Shield gas groove, 20 ... Protective glass, 21 ... Protective glass holder, 22 ... Processed optical lens, 23 ... Emission end of optical fiber, 24 ... Recovered phosphorus 25, a recovery groove, 26, an exhaust pipe, 29, a storage room, 30, an output measuring device, 31, a second lower mold (die bed), 32, a first lower mold, 33, a welding portion, 34 ... Slide groove, 36 ... Nozzle, 38: Adjustment screw, 39: Spring, A, B, C, D: Weld point.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Toshinobu Yamada 2121, Asahi-cho, Mie-gun, Mie Prefecture, 2121 Nagoya, Toshiba Corporation (72) Inventor: Tetsuji Yamazoe, 2121, Ozai, Asahimachi, Mie-gun, Mie Prefecture Inside Mie Plant of Toshiba Corporation

Claims (10)

[Claims] 1. A die for forming an iron core by laminating thin plates punched by an upper die and a lower die in a lower die and joining the thin plates to each other by laser welding, and embedded in the center of the lower die. A die, a work holding hole penetrating vertically through the center of the lower die, an oil drying groove formed in a lower side surface of the die of the work holding hole, and a drying supply supplied to the oil drying groove. A gas, a plurality of laser irradiation chambers disposed at a substantially central portion of the work holding hole in a penetrating direction at right angles to the lower mold body and opened in a horizontal direction, and shielded by the laser irradiation chamber. A mold characterized by joining a thin plate by laser irradiation welding with flowing gas to form an iron core. 2. The mold according to claim 1, wherein the laser irradiation chamber is formed with a step in the vertical direction of the lower mold. 3. A center hole formed at the center of the tip of the laser irradiation chamber and a tip shield at a work holding hole side of the tip of the laser irradiation chamber, and a side shield hole is drilled between the tip shield and the lower die. The mold according to claim 1 or 2, wherein a shield gas groove is formed with the inner diameter of the holding hole, and the shield gas groove has communication with the side shield hole. 4. The mold according to claim 1, further comprising an exhaust passage in which a lower body portion is continuously connected to a lower end of the shield gas groove from a lower end thereof. 5. The mold according to claim 1, wherein one of the outlets of the exhaust passage is covered with a groove-shaped ring-shaped recovery ring, and the groove of the recovery ring forms a recovery groove. 6. The mold according to claim 1, wherein a storage chamber is provided which is pierced from the vicinity of the outer periphery of the die on the upper end surface of the lower die toward the laser irradiation chamber, and a protective glass is inserted into the storage chamber. 7. The gold according to claim 1, wherein a storage chamber is provided which is pierced from the vicinity of the outer periphery of the die on the upper end surface of the lower die toward the laser irradiation chamber, and a laser output measuring device is inserted into the storage chamber. Type. 8. A die for laminating thin plates punched by an upper die and a lower die in a lower die and joining the thin plates by laser welding to form an iron core, wherein the lower die is a first lower die and a first die. Forming work holding holes in each of the two lower molds as a divided mold, embedding a die in the center of the first lower mold, and embedding a laser irradiation device inside the second lower mold. Features mold. 9. The mold according to claim 8, wherein an optical system constituting said laser irradiation device is movable in a vertical direction. 10. The punched thin plates are sequentially laminated in a mold, and punching oil is removed by sweeping a drying gas in a laminating direction around a plurality of welding points in a circumferential direction of the laminated thin plates. With the gas flowing in the lamination direction from the welding point and before and after, the laser is irradiated to start welding between the laminations from one of the plurality of welding points in the circumferential direction in the laminating direction. Thereafter, welding of one or more subsequent thin plates is performed in a laminating direction from a welding point different from the one welding point and the other welding points to bind and form an iron core in a mold. Forming method.