Preheating device

Abstract

To provide a preheating device that can preheat a workpiece in a short time before heat compression molding. [Solution] A preheating device 10 for preheating a workpiece W before heat compression molding, comprising a first heating unit 50. The first heating unit 50 is provided so as to be in contact with the workpiece W before heat compression molding and is capable of heating the workpiece W.

Description

Technical Field

[0001] The present invention relates to a preheating device.

Background Art

[0002] Conventionally, in the manufacturing process of an electrode body of a rectangular battery, it is known to compress-mold the electrode body at a high temperature. For example, Patent Document 1 describes that while applying heat to an electrode body composed of a wound body wound in a flat shape, it is compression-molded under pressure, crushed from the diameter direction to make the cross-sectional shape elliptical, and then housed in a can case of a rectangular battery. It is said that by doing so, the gaps and spaces inside the electrode body can be eliminated, and the battery capacity per unit volume of the can case housing the electrode body can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, Patent Document 1 states that "if compression is performed before the electrode body warms up, a difference will occur in the softening of the electrode due to heat, and there is a risk of peeling of a part of the positive electrode active material or the negative electrode active material from the current collector due to stress concentration." Therefore, before the above-described high-temperature compression molding, as a pretreatment, it is preferable to provide a step of heating and holding (preheating) for 30 minutes or less at a temperature not exceeding the melting point of the plastic sheet, which is one of the materials constituting the electrode body (wound body).

[0005] However, Patent Document 1 does not disclose a specific method for preheating the electrode body before heat compression molding. For example, when preheating by radiation heating, it may take a long time until the preheating is completed.

[0006] Furthermore, when preheating by radiant heating, it is necessary to indirectly preheat the electrode body by heating the ambient gas, which may increase energy consumption during the preheating process.

[0007] The object of the present invention is to provide a preheating device that can preheat a workpiece in a short time before heat compression molding. Alternatively, it is to provide a preheating device that can efficiently preheat a workpiece before heat compression molding. [Means for solving the problem]

[0008] This invention relates to the process before heat compression molding. Electrode body (5) A preheating device for preheating a workpiece (W), comprising a heating unit (50). The heating unit is provided so as to be in contact with the workpiece before heat compression molding, and is capable of heating the workpiece. In this invention, by heating the workpiece while the heating unit is in contact with it, the workpiece can be preheated in a short time before heat compression molding.

[0009] Furthermore, in this invention, by actively heating the workpiece itself while the heating element is in contact with the workpiece, it is possible to reduce unnecessary energy consumption and efficiently preheat the workpiece compared to when the workpiece is heated indirectly by radiant heating. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing a preheating device according to one embodiment. [Figure 2] Cross-sectional view along line II-II in Figure 1. [Figure 3] A diagram showing the manufacturing process of a lithium-ion secondary battery, where (A) shows the coating process, (B) shows the pressing process, (C) shows the slitting process, (D) shows the winding process, (E) shows the preheating process, (F) shows the heat compression molding process, (G) shows the cell assembly process, (H) shows the drying process, and (I) shows the liquid injection process. [Figure 4] Enlarged view of section IV in Figure 2. [Figure 5] Enlarged view of section V in Figure 1. [Figure 6] This is an enlarged view of section V in Figure 1, showing a different state from that in Figure 5. [Figure 7] Figure 5 is a view from the direction of arrow VII. [Figure 8] Figure 5 shows a cross-sectional view along line VIII-VIII. [Figure 9] Figure 6 shows a cross-sectional view of the line IX-IX. [Figure 10] A diagram showing experimental results regarding the heating of the workpiece. [Modes for carrying out the invention]

[0011] A preheating device according to one embodiment will be described below with reference to the drawings. Substantially identical components will be denoted by the same reference numerals, and their descriptions will be omitted. Furthermore, if multiple identical components exist within the drawings, reference numerals will be omitted as appropriate to avoid complexity.

[0012] (One embodiment) Figures 1 and 2 show a preheating device according to one embodiment. The preheating device 10 of this embodiment is used in the "preheating process" (Figure 3(E)) of the "lithium-ion secondary battery manufacturing process" shown in Figure 3 to preheat the workpiece W before it is heated and compressed in the next process, the "heat compression molding process" (Figure 3(F)).

[0013] First, we will explain the manufacturing process of lithium-ion secondary batteries shown in Figure 3. (Coating process) As shown in Figure 3(A), in the "coating process," a slurry 2, which is a viscoelastic composite coating obtained by mixing an active material, a conductive additive, and a binder with a suitable solvent, is applied to the current collector 1, which is made of metal foil, by the coating unit 12. Then, by volatilizing the solvent in the slurry 2, for example by passing it through a drying oven, an electrode composite 3 is formed on the current collector 1.

[0014] (Pressing process) As shown in Figure 3(B), in the subsequent "pressing process," the electrode composite material 3 formed on the current collector 1 is compressed by the press roller 13 to form the electrode sheet 4.

[0015] (Slitting process) As shown in Fig. 3(C), in the subsequent "slitting process", according to the target cell shape, the electrode sheet 4 is cut by the slitter 14 so as to have the required dimensions.

[0016] (Winding process) As shown in Fig. 3(D), in the subsequent "winding process", the positive and negative electrodes, which are the electrode sheets 4 formed up to the previous process, are laminated through a porous plastic sheet (not shown) as a separator for insulating them, and this is wound flatly to form an electrode body 5 composed of a wound body having an oval cross-sectional shape. The electrode body 5 is provided with tabs 6 for taking out current from the positive and negative electrodes.

[0017] (Preheating process) As shown in Fig. 3(E), in the subsequent "preheating process", the work W, which is the electrode body 5 formed in the previous process, is preheated by the preheating device 10. If "heating and compression molding" is performed in the next process before the electrode body 5 warms up, there may be a difference in the softening due to heat of the electrode body 5 (separator), and thus there is a possibility of peeling from the current collector 1 to the electrode composite material 3 (a part of the positive electrode active material and the negative electrode active material) due to stress concentration. By preheating the electrode body 5 in the "preheating process" before the "heating and compression molding process", the possibility of the above problem occurring can be reduced. The configuration of the preheating device 10 of the present embodiment and the preheating of the work W by the preheating device 10 will be described in detail later.

[0018] (Heating and compression molding process) As shown in Fig. 3(F), in the subsequent "heating and compression molding process", the electrode body 5 (work W) preheated in the previous process is compressed while being heated by the mold 15 that generates heat. Thereby, the gaps and spaces inside the electrode body 5 can be eliminated, and the battery capacity per unit volume of the manufactured lithium-ion secondary battery can be improved.

[0019] (Cell assembly process) As shown in Fig. 3(G), in the subsequent "cell assembly process", one or more electrode bodies 5 heat-compression molded in the previous process are put into a metal can case 7 to assemble the cell 8.

[0020] (drying process) As shown in Figure 3(H), in the subsequent "drying process," the drying device 11 dries the inside of the cell 8's can case 7 (electrode body 5). This suppresses performance degradation in lithium-ion secondary batteries, which can be reduced due to moisture contamination.

[0021] (liquid injection process) As shown in Figure 3(I), in the subsequent "liquid injection process," electrolyte is poured into the can case 7 from the injection section 16 through the injection port 9. After that, the injection port 9 is sealed, and after the inspection process, the manufacturing process of the lithium-ion secondary battery (cell 8) is completed.

[0022] Next, the preheating device 10 of this embodiment will be described.

[0023] The preheating device 10 is a preheating device that preheats the workpiece W before it is heated and compressed in the "heating and compression molding process," and as shown in Figures 1 and 2, it comprises a device support section 20, a furnace body 30, a movable unit 40, a first heating section 50 and a second heating section 60 as "heating sections," a conveyor belt 70, a conveyor belt drive section 80, and the like.

[0024] As shown in Figures 1, 5, and 7, the device support section 20 includes a lower support 21, a side support 22, a side support 23, an upper support 24, a leg section 25, a support base section 26, a support 27, and a roller support 28.

[0025] The lower support 21 is formed, for example, in the shape of a long plate and is installed substantially parallel (horizontal) to the ground or floor. The side support 22 is formed, for example, in the shape of a column and two are provided on the vertically upper surface of one end of the lower support 21 in the longitudinal direction, with their longitudinal direction aligned with the vertical direction. The side support 23 is formed, for example, in the shape of a column and two are provided on the vertically upper surface of the other end of the lower support 21 in the longitudinal direction, with their longitudinal direction aligned with the vertical direction.

[0026] The upper support 24 is formed, for example, in the shape of a long plate and is provided so as to be substantially parallel (horizontal) to the lower support 21. Here, both ends of the upper support 24 in the longitudinal direction are supported by the side supports 22 and 23. The legs 25 are provided, for example, between the vertically lower surfaces of both ends of the lower support 21 in the longitudinal direction and the ground or floor, and support the lower support 21.

[0027] The support base 26 is located inside the furnace body 30, which will be described later. The support body 27 is located between the two side support bodies 22 (see Figure 7). Two roller support bodies 28 are located vertically above the support body 27, aligned vertically (see Figure 7).

[0028] The furnace body 30 includes a lower furnace body wall portion 31, an upper furnace body wall portion 32, a side furnace body wall portion 33, a furnace body inlet wall portion 35, a furnace body outlet wall portion 36, etc. (see Figures 1 and 7). The lower furnace body wall portion 31 is formed, for example, in the shape of a long plate and is provided on the vertically upper side of the upper support 24 such that its longitudinal direction is aligned with the longitudinal direction of the upper support 24. The upper furnace body wall portion 32 is formed, for example, in the shape of a long plate and is provided on the vertically upper side of the lower furnace body wall portion 31 such that its longitudinal direction is aligned with the longitudinal direction of the lower furnace body wall portion 31, while maintaining a predetermined distance between it and the lower furnace body wall portion 31. The furnace body side wall portion 33 is formed, for example, in the shape of a long plate, and one is provided on each side of the shorter direction of the furnace body lower wall portion 31 and furnace body upper wall portion 32, with its longitudinal direction aligned with the longitudinal direction of the furnace body lower wall portion 31 and furnace body upper wall portion 32, and its short direction aligned with the vertical direction. The furnace body lower wall portion 31, the furnace body upper wall portion 32, and the two furnace body side wall portions 33 form a rectangular cylindrical furnace body portion 300.

[0029] The furnace inlet wall 35 is formed, for example, in the shape of a rectangular plate and is provided to close the opening at one end of the furnace cylinder 300. A furnace inlet 301 is formed in the furnace inlet wall 35, penetrating the furnace inlet wall 35 in the thickness direction. The furnace inlet 301 is formed in a rectangular shape in the center of the furnace inlet wall 35 (see Figure 7). The furnace outlet wall 36 is formed, for example, in the shape of a rectangular plate and is provided to close the opening at the other end of the furnace cylinder 300. A furnace outlet 302 is formed in the furnace outlet wall 36, penetrating the furnace outlet wall 36 in the thickness direction. The furnace outlet 302 is formed in a rectangular shape in the center of the furnace outlet wall 36.

[0030] The movable unit 40 includes a lower movable part 41, an upper movable part 42, a connecting part 43, a cylinder shaft 44, and an air cylinder 45 (see Figure 5).

[0031] The lower movable part 41 is formed, for example, in the shape of a rectangular plate and is provided inside the furnace body 30 so as to be substantially parallel to the lower wall portion 31 and the upper wall portion 32 of the furnace body. The upper movable part 42 is formed, for example, in the shape of a rectangular plate and is provided outside (upper part) of the furnace body 30, above the upper wall portion 32 in the vertical direction, so as to be substantially parallel to the upper wall portion 32 of the furnace body with a predetermined distance between them. The connecting part 43 is formed, for example, in the shape of a cylinder and is provided so as to pass through the furnace body hole portion 321 formed in the upper wall portion 32 of the furnace body. There are four connecting parts 43, which connect the four corners of the lower movable part 41 and the four corners of the upper movable part 42. As a result, the lower movable part 41, the upper movable part 42 and the connecting part 43 can move back and forth vertically as a single unit.

[0032] The cylinder shaft 44 is formed, for example, in a cylindrical shape, and one end is provided so as to connect to the center of the upper movable part 42 on the side of the furnace body upper wall 32. The air cylinder 45 is provided on the vertically upper surface of the furnace body upper wall 32 at a position corresponding to the cylinder shaft 44. The other end of the cylinder shaft 44 is inserted into the air cylinder 45.

[0033] When air is supplied to the air cylinder 45 by a control unit (not shown), the cylinder shaft 44 moves vertically upward. As a result, the lower movable part 41, the upper movable part 42, and the connecting part 43 move vertically upward as a single unit. When the air supplied to the air cylinder 45 is released, the lower movable part 41, the upper movable part 42, and the connecting part 43 move vertically downward as a single unit due to their own weight.

[0034] In this embodiment, eight movable units 40 are provided along the longitudinal direction of the furnace body 30 (see Figure 1).

[0035] The first heating section 50 includes a plate 51 and heaters 52. The plate 51 is formed in the shape of a rectangular plate, for example, from a metal such as aluminum. The heaters 52 are, for example, sheathed heaters that generate heat when electricity is applied, and are formed in the shape of a rod. The heaters 52 are provided so as to be housed in holes formed inside the plate 51 that extend along the longitudinal direction. For example, seven heaters 52 are provided at equal intervals in the short direction of the plate 51.

[0036] The first heating section 50 is provided on the vertically lower surface of the lower movable section 41 of the movable unit 40. The first heating section 50 is provided so that its longitudinal direction is aligned with the short direction of the lower movable section 41. For example, five first heating sections 50 are provided at equal intervals along the longitudinal direction of one lower movable section 41. That is, 40 first heating sections 50 are provided at equal intervals along the longitudinal direction of the furnace body 30. The first heating section 50 is movable vertically upward or downward in conjunction with the lower movable section 41 of the movable unit 40.

[0037] The support base portion 26 described above is formed in a rectangular shape such that its vertically upper surface corresponds to the shape of the lower movable portion 41 of the movable unit 40, and is provided on the vertically upper surface of the lower wall portion 31 of the furnace body at a position corresponding to the lower movable portion 41. Like the lower movable portion 41, eight support base portions 26 are provided in the longitudinal direction of the furnace body 30 (see Figure 1).

[0038] The second heating section 60 includes a plate 61 and heaters 62. The plate 61 is formed in the shape of a rectangular plate, for example, from a metal such as aluminum. The heaters 62 are, for example, sheathed heaters that generate heat when electricity is applied, and are formed in the shape of a rod. The heaters 62 are provided so as to be housed in holes formed inside the plate 61 that extend along the longitudinal direction. For example, seven heaters 62 are provided at equal intervals in the short direction of the plate 61.

[0039] The second heating section 60 is provided on the vertically upper surface of the support base 26. The second heating section 60 is provided so that its longitudinal direction is aligned with the short direction of the support base 26. For example, five second heating sections 60 are provided at equal intervals along the longitudinal direction of the support base 26. That is, the second heating section 60 is provided vertically below the first heating section 50 to correspond to the first heating section 50. Similar to the first heating section 50, forty second heating sections 60 are provided at equal intervals along the longitudinal direction of the furnace body 30.

[0040] The conveyor belt 70 is formed in a belt shape by, for example, arranging a sheet of fluororesin in a ring shape. The conveyor belt 70 passes through the furnace inlet 301 and the furnace outlet 302, and is positioned so that the second heating section 60, the support base section 26, and the lower furnace wall section 31 are located on its inside. That is, the upper vertical portion of the conveyor belt 70, which is provided in a ring shape, is located inside the furnace body 30, and the lower vertical portion is located outside (below) the furnace body 30 (see Figures 1 and 5). The conveyor belt 70 is located inside the furnace body 30 between the first heating section 50 and the second heating section 60 (see Figure 5). Here, the width of the conveyor belt 70 is approximately the same as the longitudinal length of the first heating section 50 and the second heating section 60 (see Figure 4).

[0041] The conveyor belt drive unit 80 includes a drive motor 81, a drive belt 82, a tensioner 83, a drive pulley 71, rollers 72-75, a tensioner roller 76, and rollers 77 and 78.

[0042] The drive motor 81 is located near the side support 23. The tensioner 83 is located near the side support 22. The drive pulley 71 is attached to the output shaft of the drive motor 81. Rollers 72-74 and 78 are rotatably mounted above the drive motor 81. The tensioner roller 76 is rotatably supported by the tensioner 83. Rollers 75 and 77 are located above the tensioner roller 76.

[0043] The conveyor belt 70 is wound around rollers 72-75, tensioner roller 76, rollers 77 and 78. The drive belt 82 is wound around the drive pulley 71 and roller 72. A workpiece W can be placed on the upper vertical surface of the conveyor belt 70. In this embodiment, the workpiece W is an electrode body 5 consisting of a wound body with an oval cross-section. The workpiece W is formed in the shape of a rectangular plate. The workpiece W is placed on the conveyor belt 70 so that its longitudinal direction is aligned with the width direction of the conveyor belt 70 (see Figure 4). The longitudinal length of the workpiece W is smaller than the width of the conveyor belt 70.

[0044] When the drive motor 81 is energized by a control unit (not shown), the drive pulley 71 rotates, causing the roller 72 to rotate. This causes the conveyor belt 70 to rotate, and the conveyor belt 70 moves horizontally inside the furnace body 30. In this embodiment, the conveyor belt 70 moves in the direction from the furnace body inlet 301 to the furnace body outlet 302. Hereinafter, the direction of movement of the conveyor belt 70 inside the furnace body 30 will be referred to as the "conveying direction" of the workpiece W.

[0045] The tensioner 83 can adjust the tension of the conveyor belt 70 by moving the tensioner roller 76 in the vertical direction. Here, the tensioner roller 76 may be passively moved by biasing it vertically downward, for example by a spring, or it may be driven vertically in accordance with the tension of the conveyor belt 70 by a control unit (not shown).

[0046] In this embodiment, the preheating device 10 further includes a belt support section 90 (see Figure 5). The belt support section 90 has a movable support section 91 and a support roller 92. The movable support section 91 is provided so as to be able to reciprocate vertically between adjacent support base sections 26. The support roller 92 is provided at the end of the movable support section 91 so as to be able to contact and rotate the vertically lower surface of the conveyor belt 70 inside the furnace body 30. The belt support sections 90 are provided between adjacent support base sections 26. That is, seven belt support sections 90 are provided at equal intervals in the longitudinal direction of the furnace body 30.

[0047] The belt support section 90 supports the conveyor belt 70 from below in the vertical direction by bringing the support section roller 92 into contact with the conveyor belt 70, thereby suppressing the bending of the conveyor belt 70 inside the furnace body 30. This prevents the conveyor belt 70 from coming into contact with the second heating section 60 when the workpiece W is being conveyed.

[0048] Next, the operation of the preheating device 10 in the preheating process will be described.

[0049] When the preheating process begins, a control unit (not shown) energizes the heater 52 of the first heating unit 50 and the heater 62 of the second heating unit 60, and waits until plates 51 and 61 reach a predetermined temperature. In this embodiment, the predetermined temperature (set temperature of the heating unit) is, for example, about 90°C.

[0050] Next, the control unit controls the robot or workpiece placement device to place the workpiece W in front of the furnace inlet 301 on the conveyor belt 70. Subsequently, the control unit drives the drive motor 81. This causes the conveyor belt 70 to move, and the workpiece W is transported from the furnace inlet 301 into the furnace body 30. When the workpiece W is transported to a position vertically below the first heating unit 50, the control unit stops the operation of the drive motor 81. This leaves the workpiece W in a position vertically below the first heating unit 50 (see Figures 5 and 8).

[0051] Next, the control unit controls the robot or workpiece placement device, etc., to place another workpiece W in front of the furnace inlet 301 of the conveyor belt 70, while simultaneously releasing the air from the air cylinder 45 and moving the belt support section 90 vertically downward. By releasing the air from the air cylinder 45, the first heating section 50 moves vertically downward together with the lower movable section 41. When the first heating section 50 moves vertically downward, the plate 51 of the first heating section 50 comes into contact with the upper surface of the workpiece W, and the conveyor belt 70 moves vertically downward together with the workpiece W. As a result, the vertically lower surface of the conveyor belt 70 comes into contact with the upper surface of the plate 61 of the second heating section 60, and the workpiece W and the conveyor belt 70 are sandwiched between the first heating section 50 and the second heating section 60 (see Figures 6 and 9). In this state, the workpiece W is heated by the first heating section 50 and the second heating section 60.

[0052] After a predetermined time has elapsed in this state, the control unit supplies air to the air cylinder 45 and moves the belt support unit 90 vertically upward. By supplying air to the air cylinder 45, the first heating unit 50 moves vertically upward together with the lower movable unit 41. When the first heating unit 50 and the belt support unit 90 move vertically upward, the conveyor belt 70 separates from the plate 61 of the second heating unit 60, and the plate 51 of the first heating unit 50 separates from the upper surface of the workpiece W (see Figures 5 and 8).

[0053] Next, the control unit drives the drive motor 81. This moves the conveyor belt 70, and another workpiece W is conveyed from the furnace inlet 301 into the furnace body 30. Thereafter, by repeating the same operation, multiple workpieces W can be heated continuously and intermittently by the first heating unit 50 and the second heating unit 60. The workpieces W that have been conveyed to the outside of the furnace body 30 from the furnace outlet 302 are preheated so that the temperature of the center (inside) reaches a predetermined temperature. In this embodiment, the predetermined temperature (preheating completion temperature) is, for example, about 70°C.

[0054] The workpiece W, preheated in the preheating process (preheating device 10), is transported to the mold 15 and subsequently subjected to heat compression molding in the "heat compression molding process".

[0055] In this embodiment, by including the furnace body 30, it is possible to suppress the dissipation of heat generated in the first heating section 50 and the second heating section 60 to the surroundings of the preheating device 10.

[0056] Next, Figure 10 shows the experimental results regarding the heating (preheating) of workpiece W.

[0057] The solid lines in Figure 10 show the change in temperature of the first heating section 50 (heater 52) and the second heating section 60 (heater 62) of the preheating device 10 from the start of heating (heating time: 0 minutes). Note that the temperature of the first heating section 50 and the second heating section 60 has risen to a predetermined temperature (approximately 90°C) at 0 minutes from the start of heating. The dashed line in Figure 10 shows the change in temperature of the center of the workpiece W when the workpiece W is sandwiched between the first heating section 50 and the second heating section 60 in contact with the workpiece W in a chamber with a predetermined internal space, from the start of heating (heating time: 0 minutes). The double dashed line in Figure 10 shows the change in temperature of the center of the workpiece W when the workpiece W is radiated by the first heating section 50 and the second heating section 60 at a predetermined distance from the workpiece W in a chamber with a predetermined internal space, from the start of heating (heating time: 0 minutes).

[0058] As shown in Figure 10, in contact heating, where the first heating unit 50 and the second heating unit 60 are in contact with and sandwich the workpiece W, the temperature of the center of the workpiece W reaches the desired preheating temperature (approximately 70°C) in about 4 minutes and 30 seconds from the start of heating (preheating). On the other hand, in radiant heating, where the first heating unit 50 and the second heating unit 60 are separated from the workpiece W by a predetermined distance, the temperature of the center of the workpiece W reaches the desired preheating temperature (approximately 70°C) in about 20 minutes from the start of heating (preheating). In other words, it can be seen that contact heating can significantly shorten the preheating completion time compared to radiant heating.

[0059] As shown in Figure 5, in this embodiment, multiple plates 51 of the first heating section 50 and plates 61 of the second heating section 60 are provided at predetermined intervals s1 in the conveying direction. The workpieces W conveyed by the conveyor belt 70 are conveyed (placed) at predetermined intervals s2 in the conveying direction. Therefore, in the preheating process described above, the temperature of each workpiece W rises in a stepwise manner as it is conveyed inside the furnace body 30 from the furnace body inlet 301 to the furnace body outlet 302. As shown in the experimental results described above, in contact heating, the desired preheating temperature (approximately 70°C) is reached in approximately 4 minutes and 30 seconds from the start of heating (preheating). Therefore, in this embodiment, for the 40 first heating sections 50 and 40 second heating sections 60 provided in the conveying direction, the contact (heating) time between each first heating section 50 and each second heating section 60 via the conveyor belt 70 and the workpiece W is set to, for example, 7 seconds. As a result, each workpiece W is heated by the first heating section 50 and the second heating section 60 for a total of 280 seconds (= 7 (seconds) × 40 (pieces)), or 4 minutes and 40 seconds, while being transported inside the furnace body 30 from the furnace body inlet 301 to the furnace body outlet 302, and reaches the desired preheating temperature (approximately 70°C).

[0060] The smaller the spacing s1 between the plates 51 of the first heating section 50 and the plates 61 of the second heating section 60, and the smaller the spacing s2 between the workpieces W, the smoother the temperature change of the workpieces W during the preheating process becomes, and the shorter the time it takes for each workpiece W to pass through the furnace body 30. Here, spacings s1 and s2 may each be set to 0. That is, the plates 51 of the first heating section 50 and the plates 61 of the second heating section 60 may be brought into contact with each other in the conveying direction, or the workpieces W may be brought into contact with each other in the conveying direction. In this case, it is preferable to omit the belt support section 90.

[0061] In this embodiment, the temperatures of the heater 52 of the first heating section 50 and the heater 62 of the second heating section 60 during the preheating process are set to approximately 90 to 100°C. Therefore, even if the preheating device 10 stops while the workpiece W is sandwiched between the first heating section 50 and the second heating section 60, it is possible to prevent the temperature of the workpiece W from exceeding the heat resistance temperature of the separator (approximately 105°C).

[0062] Furthermore, in this embodiment, the desired preheating temperature (preheating completion temperature) of the workpiece W is set to approximately 70°C, in accordance with the softening start temperature of the resin material of the workpiece W (electrode body 5).

[0063] As explained above, <1> This embodiment is a preheating device 10 for preheating a workpiece W before heat compression molding, and includes a first heating unit 50 as a "heating unit". The first heating unit 50 is provided so as to be in contact with the workpiece W before heat compression molding and is capable of heating the workpiece W. In this embodiment, by heating the workpiece W while the first heating unit 50 is in contact with it, the workpiece W before heat compression molding can be preheated in a short time.

[0064] Furthermore, in this embodiment, by actively heating the workpiece W itself while bringing the first heating unit 50 into contact with the workpiece W, it is possible to reduce excess energy consumption and efficiently preheat the workpiece W compared to the case where the workpiece W is heated indirectly by radiant heating.

[0065] Also, <2> This embodiment further includes a second heating section 60. The second heating section 60 can heat the workpiece W while it is sandwiched between the first heating section 50. Therefore, the workpiece W can be preheated in a shorter time before being heat-compressed.

[0066] Also, <3> This embodiment further includes a conveyor belt 70. The conveyor belt 70 can carry and transport workpieces W. Therefore, multiple workpieces W can be preheated continuously.

[0067] Also, <4> In this embodiment, multiple first heating units 50 are provided in the direction of transport of the workpiece W. Therefore, multiple workpieces W can be preheated continuously and efficiently.

[0068] Also, <5> In this embodiment, the second heating unit 60 can heat the workpiece W while the workpiece W and the conveyor belt 70 are sandwiched between it and the first heating unit 50. This allows the workpiece W to be heated (preheated) by the first heating unit 50 and the second heating unit 60 while being conveyed by the conveyor belt 70.

[0069] Also, <6> In this embodiment, the first heating section 50 and the second heating section 60 are provided in multiple locations in the direction of transport of the workpiece W. Therefore, multiple workpieces W can be preheated continuously and more efficiently.

[0070] (Other embodiments) In other embodiments, the second heating unit and the conveyor belt may be omitted, and only the first heating unit may be provided.

[0071] In other embodiments, the conveyor belt may not be provided, and the workpiece may be heated (preheated) by sandwiching it between the first heating section and the second heating section, that is, by bringing the first heating section and the second heating section into contact with the workpiece.

[0072] In other embodiments, the second heating unit may be omitted, and the workpiece may be heated (preheated) by bringing the first heating unit into contact with the workpiece while the workpiece is being transported by a conveyor belt.

[0073] In other embodiments, the first heating units may be provided in any number in the workpiece transport direction, or only one may be provided in a single preheating device. In other embodiments, the second heating units may be provided in any number in the workpiece transport direction, or only one may be provided in a single preheating device.

[0074] Furthermore, in the above-described embodiment, an example was shown where the workpiece to be preheated is an electrode body consisting of a wound body with an oval cross-sectional shape. In contrast, in other embodiments, the workpiece may be, for example, a wound body with a circular cross-sectional shape, or a laminated electrode body in which a positive electrode, a negative electrode, and a separator are stacked in the thickness direction.

[0075] Furthermore, in the above-described embodiment, an example was shown in which the first heating element is brought into contact with the workpiece from the vertically upward direction. In contrast, in other embodiments, the first heating element may be brought into contact with the workpiece from a direction other than the vertically upward direction.

[0076] Furthermore, the above-described embodiment shows an example in which the workpiece is sandwiched between the first heating section and the second heating section in the vertical direction. In contrast, in other embodiments, the workpiece may be sandwiched between the first heating section and the second heating section in a direction other than the vertical direction.

[0077] Furthermore, the preheating device according to the present invention can also be used to preheat workpieces other than the electrodes of lithium-ion secondary batteries.

[0078] Thus, this disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. [Explanation of Symbols]

[0079] 10 Preheating device, 50 First heating section (heating section), W Workpiece

Claims

1. A preheating device for preheating a workpiece (W), which is an electrode body (5), before it is subjected to heat compression molding, A preheating device comprising a heating section (50) that is provided so as to be in contact with the workpiece before it is heat-compressed and molded, and capable of heating the workpiece.

2. The heating section is the first heating section (50), The preheating device according to claim 1, further comprising a second heating unit (60) capable of heating the workpiece while the workpiece is sandwiched between it and the first heating unit.

3. The preheating device according to claim 1 or 2, further comprising a conveyor belt (70) on which the workpiece can be placed and transported.

4. The preheating device according to claim 3, wherein the heating section is provided in multiple locations in the direction of transporting the workpiece.

5. The system further includes a conveyor belt (70) on which the workpiece can be placed and transported. The preheating device according to claim 2, wherein the second heating unit is capable of heating the workpiece while the workpiece and the conveyor belt are sandwiched between it and the first heating unit.

6. The preheating device according to claim 5, wherein the first heating section and the second heating section are provided in a plurality in the direction of transporting the workpiece.

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