JP6044510B2 - Press roll device - Google Patents

Description

  The present invention relates to a press roll apparatus.

Nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are used in applications such as hybrid vehicles (HV), plug-in hybrid vehicles (PHV), and electric vehicles (EV).
A nonaqueous electrolyte secondary battery includes a positive electrode and a negative electrode that are a pair of electrodes, a separator that insulates between them, and a nonaqueous electrolyte.

As a structure of the electrode (positive electrode or negative electrode) for the nonaqueous electrolyte secondary battery, a laminated structure including a current collector and an electrode active material layer (positive electrode active material layer or negative electrode active material layer) formed thereon is used. Are known.
The positive electrode active material layer includes, for example, a positive electrode active material such as a lithium-containing composite oxide, a conductive aid such as carbon powder, a binder such as polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP). A paste containing a dispersant is applied onto a current collector such as an aluminum foil, dried, and pressed to form.
The negative electrode active material layer includes, for example, a negative electrode active material such as graphite, a binder such as modified styrene-butadiene copolymer latex (SBR), a thickener such as carboxymethyl cellulose Na salt (CMC), and a dispersant such as water. The paste containing is coated on a current collector such as copper foil, dried, and pressed to form.

In the press work, a press roll device having a pair of press rolls arranged to face each other is usually used. By passing a material to be pressed between a pair of press rolls, the material to be pressed is sandwiched between a pair of upper and lower press rolls and pressed.
In such press working, the thickness of the electrode active material layer after press working is regulated to a desired value by the separation distance between the pair of press rolls.

JP 2011-181348

In the press work by the press roll device, heat generated by material deformation of the material to be pressed and frictional heat between the pair of press rolls and the material to be pressed are generated. In the present specification, these are collectively referred to as “deformation heat”.
The deformation heat is distributed and input to the pair of press rolls and the material to be pressed.
When the press roll device is operated for a long time, the pair of press rolls is thermally expanded by the amount of heat input to the pair of press rolls, and the distance between the pair of press rolls is gradually reduced. If the operation is continued in such a state, the thickness of the obtained electrode active material layer may be smaller than a desired value.

  Patent Document 1 discloses an electrode material for a secondary battery having a cooling structure in which a heat medium is circulated through a bearing box (13) that houses and holds a bearing (14) of a press roll (11a, 11b) to take heat of the roll bearing. A roll press machine is disclosed (Claim 1, FIG. 1).

In the roll press machine described in Patent Document 1, the end of the roll shaft (11c) is cooled.
In general, the heat capacity of the press roll is large, and the followability of cooling with respect to the temperature rise is not good. Therefore, it is difficult to effectively remove the heat input to the pair of press rolls (11a, 11b) by simply cooling the end of the roll shaft (11c), and the temperature of the pair of press rolls (11a, 11b) is difficult. It is difficult to suppress the rise. Further, while it is difficult to effectively remove the heat input to the pair of press rolls (11a, 11b), the end of the roll shaft (11c) is cooled, so the temperature of the pair of press rolls (11a, 11b) Unevenness occurs, and the pair of press rolls (11a, 11b) may be distorted.

  This invention is made | formed in view of the said situation, and it aims at providing the press roll apparatus which can suppress the temperature rise of a pair of press roll and thermal expansion by this.

The press roll apparatus of the present invention is
A pair of press rolls arranged opposite to each other,
A press roll device that presses a workpiece to be pressed between the pair of press rolls,
A cooling means arranged upstream of the pair of press rolls for cooling the pressed material;
Temperature control means for controlling the cooling means so that the surface temperature of the pressed material is lower than the environmental temperature and higher than the dew point temperature.

  ADVANTAGE OF THE INVENTION According to this invention, the press roll apparatus which can suppress the temperature rise of a pair of press roll and thermal expansion by this can be provided.

It is a model side view of the press roll apparatus of one Embodiment concerning this invention. It is a model side view which shows the specific example of the press roll apparatus of FIG. It is a model side view which shows the example of a design change of the press roll apparatus of FIG.

"Press roll device"
A configuration of a press roll apparatus according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG.
The press roll apparatus 1 of this embodiment is
The apparatus includes a pair of press rolls 11 and 12 arranged to face each other, and presses the pressed workpiece 2 between the pair of press rolls 11 and 12.
The pressed workpiece 2 is a belt-like member that is continuously supplied, and an arrow from the right side to the left side in the drawing indicates the feed direction of the pressed workpiece 2.

  The press roll device 1 includes a cooling unit 20 that is disposed upstream of the pair of press rolls 11 and 12 and that cools the workpiece 2 and a temperature control unit that controls the temperature of the workpiece 2 by the cooling unit 20. 30.

A well-known thing can be used as the cooling means 20.
In the present embodiment, the cooling unit 20 is a cooling device using the heat medium 21, and includes a flow path of the heat medium 21 that flows around the workpiece 2.
The heat medium 21 circulates between the cooling means 20 and a temperature control device 33 described later, and the temperature is adjusted in the temperature control device 33.

The cooling means 20 is not particularly limited, and includes one or a plurality of cooling rolls 22 through which the heat medium 21 flows, as shown in FIG.
Each cooling roll 22 is disposed in contact with the workpiece 2 and cools the workpiece 2 while being conveyed. In the figure, the flow path of the heat medium 21 is described for only one cooling roll 22, but actually, the heat medium 21 flowing in each cooling roll 22 is temperature-controlled by the temperature adjustment device 33.

The temperature control means 30
A first thermometer 31 that measures the surface temperature of the pressed workpiece 2 cooled by the cooling means 20, and
A second thermometer 32 that measures the ambient temperature around the pair of press rolls 11, 12;
A temperature control device 33 that adjusts the temperature of the heat medium 21 based on the temperature measurement results of the first thermometer 31 and the second thermometer 32 is provided.
An example of the temperature adjustment device 33 is a chiller.
The temperature control device 33 is such that the surface temperature of the pressed workpiece 2 after cooling, which is the measured temperature of the first thermometer 31, is lower than the environmental temperature, which is the measured temperature of the second thermometer 32, and the dew point. The temperature of the heat medium 21 is adjusted so that the temperature is higher than the temperature.
For example, when the environmental conditions are room temperature 22 ° C. and humidity 40%, the dew point is 7.8 ° C. In this case, the temperature adjustment device 33 adjusts the temperature of the heat medium 21 so that the surface temperature of the pressed workpiece 2 after cooling becomes a temperature higher than 7.8 ° C. and lower than 22 ° C., for example, around 15 ° C. .
For example, the temperature adjustment device 33 uses the measured temperature of the second thermometer 32 as a reference temperature, monitors the measured temperature of the first thermometer 31, and the measured temperature of the first thermometer 31 and the second temperature The set temperature of the heat medium 21 can be determined from the difference from the measured temperature of the thermometer 32.

  In the press roll apparatus 1 of the present embodiment, the amount of heat input to the pair of press rolls 11 and 12 can be reduced by cooling the workpiece 2 in advance by the cooling means 20 before press working. In the press roll apparatus 1 of the present embodiment, the amount of heat input to the pair of press rolls 11 and 12 is reduced, so that the temperature rise of the pair of press rolls 11 and 12 and the thermal expansion caused thereby are suppressed, and the pressed workpiece 2 can be pressed with high dimensional accuracy.

  Hereinafter, in the press roll apparatus 1 of this embodiment, the principle which can reduce the heat input to a pair of press rolls 11 and 12 is demonstrated in detail.

The deformation heat generated when the pressed workpiece 2 is deformed by being pressed by the pair of press rolls 11 and 12 is defined as Q (total).
Here, the deformation heat Q (total) is the sum of the heat generated by the material deformation of the workpiece 2 and the frictional heat between the pair of press rolls 11 and 12 and the workpiece 2.
The deformation heat Q (total) generated at the deformation point of the workpiece 2 (contact point with the pair of press rolls 11 and 12) is distributed and input to the pair of press rolls 11 and 12 and the workpiece 2 to be pressed. .

When the amount of heat input to the pair of press rolls 11 and 12 is Q (Roll) and the amount of heat input to the workpiece 2 is Q (Sheet), Q (total) is expressed by the following formula (1).

The temperature of the deformation point of the pressed workpiece 2 becomes higher than other portions due to the deformation heat Q (total).
It is assumed that the temperature of the pair of press rolls 11 and 12 is uniform as a whole except for the deformation point. Similarly, it is assumed that the temperature of the workpiece 2 is uniform throughout except for the deformation point.
Let ΔT (Roll) be the temperature difference obtained by subtracting the temperature at an arbitrary point away from the deformation point of the pair of press rolls 11 and 12 from the temperature at the deformation point of the workpiece 2.
Let ΔT (Sheet) be a temperature difference obtained by subtracting the temperature at an arbitrary point away from the deformation point of the pressed workpiece 2 from the temperature of the deformed point of the pressed workpiece 2.
The thermal resistance of the pair of press rolls 11 and 12 is R (Roll), the thermal resistance of the pressed material 2 is R (Sheet), and the contact thermal resistance between the pair of press rolls 11 and 12 and the pressed material 2 Is R (Roll / Sheet).
Q (Roll) and Q (Sheet) are represented by the following formulas (2) and (3), respectively.

The following formula (4) is obtained from the above formulas (2) and (3).

In the above formula (4), R (Roll), R (Roll / Sheet), and R (Sheet), which are parameters of thermal resistance, are constants specific to the material.
From the above formula (4), it can be seen that ΔT (Sheet) should be increased in order to reduce the heat input Q (Roll) to the pair of press rolls 11 and 12.
That is, if ΔT (Sheet) is increased by cooling the workpiece 2 in advance, the ratio of the amount of heat input Q (Sheet) to the workpiece 2 in the deformation heat Q (total) increases. The amount of heat input Q (Roll) to the press rolls 11 and 12 can be reduced.
The principle explanation here is based on a simple model and is subject to various influences under actual conditions, and may differ from the above calculation results.

  There is no restriction | limiting in particular as the to-be-processed material 2, The electrode (positive electrode) for a nonaqueous electrolyte secondary battery containing a collector and the electrode active material layer (positive electrode active material layer or negative electrode active material layer) formed on it Or a negative electrode).

The positive electrode active material layer includes, for example, a positive electrode active material such as a lithium-containing composite oxide, a conductive assistant such as carbon powder, a binder such as polyvinylidene fluoride (PVDF), and N-methyl-2-pyrrolidone (NMP). A paste containing a dispersion medium is applied onto a current collector such as an aluminum foil, dried, and pressed to form.
The negative electrode active material layer includes, for example, a negative electrode active material such as graphite, a binder such as modified styrene-butadiene copolymer latex (SBR), a thickener such as carboxymethyl cellulose Na salt (CMC), and a dispersion medium such as water. The paste containing is applied onto a current collector such as copper foil, dried, and pressed to form.
The press roll apparatus 1 of this embodiment can be used for the said press work of a positive electrode active material layer or a negative electrode active material layer.

(Design change example)
As can be seen from the above formula (4), in order to reduce the heat input Q (Roll) to the pair of press rolls 11 and 12, ΔT (Roll) should be decreased as ΔT (Sheet) is increased. Is more effective. That is, it is more effective to heat the pair of press rolls 11 and 12 in accordance with cooling the workpiece 2 in advance.
For example, as shown in the press roll device 3 of the design change example shown in FIG. 3, a pair of press rolls 11 according to the cooling means 20 for cooling the workpiece 2 in advance and the temperature control means 30 for controlling the cooling means 20, A heating mechanism 50 for heating 12 to a temperature higher than the environmental temperature can be provided.
The illustrated press roll apparatus 3 includes a heating mechanism 50 that heats the pair of press rolls 11 and 12 using a heat medium 51. A flow path of the heat medium 51 is provided inside the pair of press rolls 11 and 12, and the heat medium 51 circulates between the pair of press rolls 11 and 12 and the temperature adjustment device 52, and the temperature adjustment device 52 adjusts the temperature. Is done.
In the figure, the flow path of the heat medium 51 is described only for one of the press rolls 11, but the temperature of the heat medium 51 flowing through the press rolls 11 and 12 is adjusted by the temperature adjustment device 52.

The pair of press rolls 11 and 12 is heated to a temperature higher than the environmental temperature in accordance with the pre-cooling of the workpiece 2 to reduce ΔT (Roll), thereby reducing the pair of press rolls 11 and 12. The effect of suppressing the heat input can be enhanced.
The pair of press rolls 11 and 12 may be heated to a temperature higher than the temperature at the deformation point. In this case, ΔT (Roll) is a negative value. However, in order to reduce the heat input / output of the pair of press rolls 11 and 12, it is preferable that the temperature difference between the pair of press rolls 11 and 12 and the deformation point is small, and it is particularly preferable that there is no temperature difference.
Since it is difficult to accurately measure the temperature at the deformation point, the temperature at the deformation point is actually managed at the predicted temperature (room temperature + α (° C.) (where α> 0)).

  As described above, according to this embodiment, it is possible to provide the press roll device 1 that can suppress the temperature rise of the pair of press rolls 11 and 12 and the thermal expansion caused thereby.

  The press roll apparatus of this invention can be preferably utilized for manufacture of the electrode for nonaqueous electrolyte secondary batteries, etc.

1, 3 Press roll device 2 Pressed work material 11, 12 Press roll 20 Cooling means 21 Heat medium 22 Cooling roll 30 Temperature control means 31 First thermometer 32 Second thermometer 33 Temperature control device 50 Heating Mechanism 51 Heat medium 52 Temperature control device

Claims (1)

A pair of press rolls arranged opposite to each other,
A press roll device that presses a workpiece to be pressed between the pair of press rolls,
A cooling means arranged upstream of the pair of press rolls for cooling the pressed material;
A press roll apparatus comprising temperature control means for controlling the temperature of the pressed material by the cooling means so that the surface temperature of the pressed material is lower than the environmental temperature and higher than the dew point temperature.

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