KR19980073767A - Manufacturing method of laminate - Google Patents

Abstract

The present invention relates to a method for producing a laminated board substantially free of distortion, which can solve the problems of yield reduction and quality damage of the product. The method of the present invention comprises the steps of: pressing the first heater against the upper and lower surfaces of the end plate for a predetermined time to perform proper drying; dividing the thickness of the end plate into two opposing end plates by means of a suitable divider; Thereby arranging the surfaces formed by dividing the wood planks between the opposing end plates so that the surfaces of the opposing end plates substantially coincide with each other. It consists of the steps of joining the wood planks.

Description

Manufacturing method of laminate

TECHNICAL FIELD This invention relates to the manufacturing method of laminated boards, such as plywood or LVL (laminated veneer lumber). This method uses end plates to produce a laminate that is substantially free of distortion.

Applicant of the present invention is to prepare a laminate having little or no distortion, by symmetrically laminating two end plates having substantially the same grain with respect to the centerline in the thickness direction of the laminate to be manufactured previously by an adhesive. A method was proposed (Japanese Laid-Open Patent Publication No. 2-185402).

According to this method, when the stretching force or the compressive force is generated due to the stretching or shrinkage of the single plate itself during or after the manufacture of the single plate, or the shrinkage due to the curing of the adhesive, the stretching force or the compressive force is symmetrically balanced with respect to the centerline in the thickness direction of the laminate. To achieve. Thus, if a laminate of a kind of wood is produced, such as significant warping caused by drying (eg Radiata Pine), the laminate is only slightly warped.

In the above manufacturing method, the undried end plate is divided by a divider such as a blade in the thickness direction of the end plate to obtain two end plates having substantially the same grains (hereinafter referred to as opposing end plates), and opposing end plates. Is dried to a moisture content of 5-15% suitable for bonding, and this dried end plate is superimposed on another wood plank as a center in the same manner as described above, and the product is heated by hot press. · Press to complete the bonding. However, this method has the following problems.

When using the wood veneer of the kind whose significant distortion etc. generate | occur | produce by drying, it can prevent that the dried opposing veneer moves suitably to a specific position by twisting etc. Moreover, it is difficult to manually or mechanically overlap the opposing end plates with the above-described symmetry. This leads to problems of reduced production and poor quality of production. In order to solve this problem, it has been attempted to omit the drying after splitting and superimpose the undried end plates on another wood board as a center with an adhesive, and to heat and pressurize the product. However, if the water content of the opposing veneer was high, the bonding was broken. Therefore, satisfactory laminates could not be obtained.

1 is a front view of the pressure drier 1 seen from the end plate supply side.

2 is a partial cross-sectional view taken along the line X-X of FIG.

3 is a side view of the divider 30.

4 (a)-(d) are schematic flowcharts of the process steps for producing a laminate according to the present invention.

5 is an explanatory view of a 3-ply plywood.

6 is an explanatory diagram of a center;

7 is an explanatory view of a 5-ply plywood.

Figure 8 is an explanatory view of the center of the 5-ply plywood of Figure 7;

The present invention was developed to solve the above problem. Therefore, the present invention

Pressurizing the first heater to the upper and lower surfaces of the end plate for a predetermined time to perform proper drying;

Dividing the end plate into two opposing end plates by thickness unit by a suitable divider;

Dividing the wood planks between the opposing end plates by an adhesive so that the surface created is arranged on the outer surface such that the grains of the opposing end plates substantially coincide with each other;

Provided is a method for producing a laminate, comprising a step of pressurizing a second heater against a surface produced by dividing to join an opposing end plate with a wood plank. According to the present invention, since the end plate has a top and bottom surfaces heated and pressed by the first heater for a predetermined time, the inner part of the end plate in the thickness direction is dried to the minimum to have a high level of water content. Thus, the surface divided by the divider such as the blade is satisfactory. Furthermore, the opposing end plates are substantially flat, even though the water content of the portion near the surface of the end plate heated by the first heater is substantially no overall shrinkage. As a result, it is possible to smoothly perform the continuous movement of the opposing end plates, and also to accurately overlap the opposing end plates manually or mechanically in the symmetrical relationship described above.

Therefore, even when using a single type of wood veneer in which significant warping or the like occurs due to drying, a good quality laminated board can be obtained without lowering the yield.

The time for pressurizing the first heater against the end plate is shorter than the time necessary for drying by heating and pressing, and the moisture content in the inner portion of the end plate in the thickness direction through drying by heating and pressing is applied to the fiber saturation point ( Take it to the fiber saturation point. As a result, the inner portion in the thickness direction is kept at a higher water content than the fiber saturation point. Thus, the end plate remains flat throughout.

Depending on the type of wood using the veneer, if the moisture content in the inner part of the veneer in the thickness direction is dried for a time period shorter than the time required to bring the fiber saturation point, the surface part of the veneer may There is a possibility of having a moisture content that can cause the size to shrink in a direction perpendicular to the fiber direction. If such veneers overlap opposite veneers made by dividing and are bonded to each other on wooden planks with adhesive, the resulting plywood may be warped. In order to solve this problem, in this embodiment, the time for pressing the first heater against the end plate is shorter than the time required for the end plate to start contracting in the direction perpendicular to the fiber direction. In this way, the end plate after drying by a 1st heater is substantially flat, and the obtained plywood will not be distorted.

Furthermore, it is more effective to use a heating platen having a pressurized surface with a plurality of vapor discharging grooves, respectively, from one end of the pressurized surface to the other as the first heater.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

First, the pressure drier 1 as a 1st heater used preferably for performing the laminated board manufacturing method by this invention is demonstrated.

1 is an explanatory front view of a pressure drier 1 as a first heater for drying a single plate viewed from a single plate supply side. FIG. 2 is a partial cross-sectional view taken along the line X-X of FIG. The dryer 1 is composed of a bed 4 as a base, struts 2 and 2 fixed vertically on the base 4, and an upper press plate 3. Each of the inner sides of the posts 2 and 2 is provided with a first notch 2a and a second notch 2b below the first notch.

The first heating platen 5 and the second heating platen 6 are disposed between the supports 2, 2. Each heating platen 5 and 6 has a length (size in the left and right direction in FIG. 1) of about 2,500 mm and a width (size in the left and right direction in FIG. 2) of about 1,500 mm. In each heating platen, a flexible hose (not shown) provided through the heating platen to supply steam is heated to about 150 ° C. As shown in FIG. 1, the first arm 7 extends horizontally and has a length such that the first arm 7 can be placed in the form of a leg on the first notch 2a on the first heating platen 5. (7) is fixed. Similarly, the second heating platen 6 is fixedly fixed to the first arm 8 which extends horizontally and has a length sufficient to allow the first arm 8 to be placed in the form of a leg on the second notch 2b. Attach it. The heating platens 5, 6 are brought to atmospheric conditions when each first arm 7, 8 is supported by the first and second notches 2a, 2b.

As shown in Fig. 2, the heating platens 5, 6 are more fixedly fixed to the plane perpendicular to the plane with the first arms 7, 8, and to the respective second arms 9, 10 extending horizontally. Equipped. One of the second arms 9 (right arm in FIG. 2) is rotatably provided with the rotating shaft 11 via a bearing 9a. Thus, one of the 2nd arms 10 (right arm of FIG. 2) is provided with the rotating shaft 12 rotatable via the bearing 10a. On the rotary shafts 11 and 12, a plurality of rolls 13 and 14, each about 250 mm wide, are fixedly mounted. The rolls 13 and 14 are provided with protrusions 13a and 14a in rows about 50 mm apart so that adjacent rows are about 25 mm apart in the direction of rotation and adjacent rows are about 25 mm apart in the direction perpendicular to the direction of rotation. Has a circumferential surface. A servo motor (not shown) is connected to each of the rotary shafts 11 and 12. By the servo motor, the roll 13 and the roll 14 rotate and stop in the directions indicated by the arrows, respectively.

The other one of the second arms 9 (left arm in FIG. 2) is rotatably provided with a rotation shaft via a bearing 9a. Similarly, the other one of the second arms 10 (the left arm in FIG. 2) is rotatably provided with the rotation shaft 16 via the bearing 10a. A plurality of rolls 17 and 18 having outer peripheral surfaces with protrusions 17a and 18a are fixedly mounted on the plurality of rotation shafts 15 and 16 at the same positions as the rolls 13 and 14, respectively.

Around the roll 13 and the roll 17 mounted on the first platen 5 and around the roll 14 and the roll 18 mounted on the second platen 6, respectively, the hold ( 19a, 20a and a plurality of belts 19, 20 made of stainless steel and having a thickness of about 0.5 mm and a width of about 250 mm. The bases 19a and 20a are provided in the direction of travel and in the direction perpendicular to the direction of travel at the same intervals as the projections 13a and 14a, and are about 12 mm in diameter so that the projections 13a and 14a can be inserted therein, respectively. have. Each of the belts 19 and 20 is preferably in the form of an endless belt joined together by a heat resistant adhesive tape or the like. Each belt rotates or stops the servo motor (not shown) by the rotation or stop of the rolls 13 and 14.

In addition, the lower surface of the first platen 5 and the upper surface of the second platen 6 each have a width of about 3 mm and a depth of about 2 mm, each of which extends in a direction perpendicular to the advancing direction of the belts 19 and 20 at intervals of 12 mm, respectively. (21, 22). The positions of the grooves 21 on the lower surface of the first platen 5 and the grooves 22 on the upper surface of the second platen 6 differ by about 6 mm from each other in the advancing direction of the belts 19 and 20.

Under the second heating platen 6, a supporting plate 23 having the same size as the second heating platen 6 and having a greater strength than the second heating platen 6 is disposed. On the bottom plate 4, a pressure controlled hydraulic cylinder 24 capable of vertically moving the support plate 23 is mounted.

As shown in Fig. 2, a supply conveyor 25 for supplying end plates between the first and second heating platens 5 and 6 is disposed on the upstream side of the belts 19 and 20 (left side in Fig. 2). And the delivery conveyor 26 which delivers the end plate being dried is arrange | positioned on the downstream side (right side of FIG. 2).

Hereinafter, one form of the divider which divides a single plate into two pieces is used suitably used by the manufacturing method of the laminated board by this invention. The divider 30 is described in detail in Japanese Patent Laid-Open Publication No. 185402/1990 filed by the assignee of the present invention and also used herein for reference. As illustrated in Fig. 3, the divider 30 is rotated by a base (not shown) and a motor (not shown) supported by the base in the direction indicated by the arrow and faces the drive shaft 31 perpendicular to each other. 32). On the drive shafts 31 and 32, a plurality of engagement transfer rolls 35 and 36 having outer circumferential surfaces with biting members at regular intervals in the rotational direction are regulated in the axial direction of the drive shafts 31 and 32, respectively. Mount at regular intervals. The rolls 35 and 36 oppose each other perpendicularly at the shortest distance between the ends of the engaging members 33 and 34 of about 1 to 2 mm.

A regulating member 37 is disposed between all neighboring rolls 35 on the drive shaft 31. Similarly, the adjustment member 38 is arranged between all neighboring rolls 36 on the drive shaft 32. The adjusting members 37 and 38 face each other perpendicularly. Specifically, as shown in Fig. 3, the adjusting members 37 and 38 are supported by the base (not shown) at one end, and the corner points 37a and 38a at the other end are connected to the rotation shafts of the drive shafts 31 and 32. It is located on the transmission side (right side of FIG. 3) of the vertical virtual line to connect, and is located opposite the same distance from the horizontal virtual line passing through the center point between the drive shafts 31 and 32. FIG. The adjusting members 37, 38 are arranged such that the distance between the opposite edge points 37a, 38a corresponds to 90% of the end plate thickness to be divided.

On the transmission side (downstream side) of the adjusting members 37 and 38, the edges are on a horizontal virtual line, and the divided blades face toward the supply side (upstream side) and the edge angle α is divided into 24 degrees by a horizontal virtual line ( 39) is fixedly attached to the base (not shown).

The divider further comprises a detaching member 40 which horizontally faces the regulating members 37, 38, and which faces each other perpendicularly. The separating members 40, 41 are also supported at one end by the base (not shown), and the other ends 40b, 41c are in engagement with the rotational trajectory of the end of the engagement member 33 of the engagement transfer roll 35, respectively. The rotational trajectory of the end of the engagement member 34 of the roll 36 is located in the vicinity of the dividing blade 39 providing the surfaces 40a and 41a that intersect.

On the supply side of the engagement transmission rolls 35 and 36, the conveyor 42 which supplies a single plate between the adjustment members 37 and 38 is arrange | positioned. The conveyor 42 may be the transfer conveyor 26 of the pressure drier 1.

Hereinafter, with reference to FIG. 4, the case of manufacturing a 3-ply plywood (laminated board) from the center and the end plate 50 is demonstrated by one Example of the manufacturing method of the laminated board by this invention.

First, in the pressure drier 1 shown in FIG. 1 and FIG. 2, the pressure of the hydraulic cylinder 24 during pressurization is set in advance so that it may be about 2 kg per square centimeter of the single plate 50 which is not dried. As shown in Fig. 2, the feed conveyor 25 is driven in the direction indicated by the arrows, and the rolls 13 and 14 rotate in the directions indicated by the arrows to move the belts 19 and 20, respectively. Radiata Pine veneer 50 having a thickness of about 3 mm, an area of 1,800 mm in the fiber direction, and an area of 900 mm in the direction perpendicular to the fiber direction, is placed on the feed conveyor 25 so that the delivery direction is perpendicular to the fiber direction. Release.

The end plate 50 is conveyed by the feed conveyor 25 and then by the belt 19. When the end plate arrives at the center position of the second heating platen 6, the supply conveyor 25 and the rolls 13 and 14 stop. In this connection, the holes 19a and 20a and the grooves 21 and 22 of the belts 19 and 20 are arranged as described above, so that the holes 19a and 20a and the grooves 21 and 22 become belts 19 and 20. ) Overlap with each other regardless of the position where it stops.

Thereafter, the hydraulic cylinder 24 is driven to ascend, whereby the supporting plate 23 is raised to come in contact with the second heating platen 6. The support plate 23 is further raised, and then the second heating platen 6, which is supported so that the first arm 8 is placed in the shape of a leg on the second notch 2b, is raised with the end plate 50 placed thereon. . The supporting plate 23 is further raised, whereby the second heating platen 6 is further raised to come into contact with the first heating platen 5 via the end plate. As a result, the first heating platen 5 comes into contact with the pressing plate 3. The support plate 23 is further raised with the first platen in contact with the top cover plate until the preset hydraulic cylinder 24 pressure is reached. Thereupon the ascent of the support plate stops (see Fig. 4 (a)).

Thereby, the end plate 50 is pressurized between the 1st heating platen 5 and the 2nd heating platen 6, and is heated by the heat of the heating platens 5 and 6 which are transmitted to it through the belts 19 and 20, respectively. By evaporating the moisture contained in the end plate 50. If the plate is in closed condition, the resulting vapor cannot be evaporated from the plate. However, as described above, the holes 19a and 20a of the belts 19 and 20 in contact with the end plate 50 are in line with the grooves 21 and 22, respectively. Vapor is discharged from the holes 19a and 20a into the grooves 21 and 22 to the atmosphere from the ends of the grooves 21 and 22.

Drying in this way is carried out for about 30 seconds to 1 minute. After that, the hydraulic cylinder is operated and raised, thereby lowering the support plate 23 to its original position. As a result, the first platen 5 and the second platen 6 are supported in place so that the leg-shaped first arms 7 and 8 rest on the first notch 2a and the second notch 2a, The end plate 50 is made into the standby state on the 2nd platen 6.

In the above handling, by controlling the contact time, that is, the pressing time, of the upper and lower surfaces of the end plate 50 and the first and second heating platens 5 and 6 appropriately, the inner portion in the thickness direction starts to shrink. While appropriately drying to a moisture content above the saturation point, the side plates in the thickness direction near the surface pressed against the first and second heating platens 5, 6 may be formed so that the moisture content is about 5 to about 20%. 50) can be dried. As a result, the end plate 50 as a whole does not substantially shrink. Thus, it is still possible to obtain a product which has been substantially flattened.

The rolls 13 and 14 are then rotated again in the direction indicated by the arrows, and the transfer conveyor 26 is started to move. This transfers the end plate 50 from the belt 19 to the delivery conveyor 26. Thereafter, the upper and lower surfaces of the plate 50, which are appropriately dried, are supplied to the divider 30 and converted into thicknesses to divide the plate into two parts. In this combination, the end plate 50 is placed on the feed conveyor 42 of the divider 30 so that the delivery direction is perpendicular to the fiber direction.

In the divider, the end plate 50 is supplied between the adjusting members 37 and 38, and is transferred while engaging the upper and lower surfaces of the end plate with the engaging members 33 and 34 of the rotating engagement transfer rolls 35 and 36. . That is, it transmits in the state which fixed the end plate 50 firmly. The end plate 50 is then pressed in the thick direction by the corner points 37 and 38 of the other ends of the adjusting members 37 and 38, thereby splitting the end plate without generating substantially undesired gaps. By (39), it converts into thickness into the single plates 50a and 50b (henceforth opposing single plate) whose thickness is about 1.5 mm, respectively, and divides into pieces. The opposing end plates 50a and 50b are still engaged with the engagement members 33 and 34 even after the nutrients, respectively. However, since there are separating members 40 and 41 having surfaces 40a and 41a that intersect the rotational trajectories of the engaging members 33 and 34, respectively, the engaging members 33 and 34 are sequentially turned by the surfaces 40a and 41a. ) And separate opposing end plates 50a and 50b. Thereafter, the opposite end plates 50a and 50b are transferred in the right direction (see Figs. 3 and 4 (b)).

When cutting or splitting wood into blades, the surface produced by cutting or splitting is generally preferred when the wood has a water content of at least 30%. In the dividing operation, the inner portion of the end plate 50 in the thickness direction is not properly or almost dried, and thus has a high water content. Therefore, the surfaces of the opposing end plates 50a and 50b generated by dividing into the splitting blades 39 are satisfactory.

In the opposing end plates 50a and 50b prepared in this manner, each surface portion heated by the heating platen has a low water content as described above. However, the whole of the end plates 50a and 50b is not substantially shrunk, so that it is still substantially flat as in the end plate 50.

As a result, continuous transfer of the opposite end plate mentioned later is performed smoothly. Furthermore, as described above, it is possible to superimpose the opposing end plates 50a and 50b on the upper and lower surfaces of the center accurately and manually or mechanically in a symmetrical relationship.

If the undivided end plate 50 has a non-uniform moisture content in the fiber direction and / or its vertical direction, the nonuniformity is still substantial even after the division since the moisture content is nonuniform in the resulting opposing end plates 50a and 50b. The phase remains unchanged. In general, however, the nonuniformity of the water content in the opposing end plates 50a and 50b should be regarded as substantially the same.

Apart from this, the center of the same planar size as the opposing end plates 50a and 50b, the fiber direction is perpendicular to the fiber direction of the opposing end plates 50a and 50b, and has a total water content of about 10% and a thickness of about 3 mm. 51) is prepared. Urea resin adhesive which is one of the thermosetting adhesives is added to the upper and lower surfaces of the center 51. On the center 51 an opposing end plate is formed in such a manner that the side pressing the first and second heating platens 5, 6 is adjacent to the center 51, i.e., the side created by the division can form another surface. 50a and 50b are superimposed so that the grains of the opposing end plates 50a and 50b may substantially coincide with each other (see Fig. 4 (c)). Thereafter, a heat press 100 as a second heater having substantially the same structure as the pressure drier 1 shown in Figs. 1 and 2 is used. In this case, the pressure of the hydraulic cylinder 24 is set in advance so that about 8 kg per square centimeter of the end plate normally used for joining, and the temperature of the 1st and 2nd heating platens 101 and 102 will be 160 degreeC. Bonding is performed by pressurizing the product obtained by overlapping between the 1st and 2nd heating platens 101 and 102 for about 5 minutes using the heat press which has a structure as mentioned above. As a result, the moisture contained near the surface by the division of the opposing end plates 50a and 50b evaporates, and the generated vapor is drawn from the holes 19a and 20a to the grooves 21 and 22, and the grooves 21 and 22 To the atmosphere from the end. Therefore, it is possible to considerably prevent a so-called puncture of poor bonding due to the vapor pressure, and to dry the opposite end plates 50a and 50b in a short time, so that the overall moisture content is substantially uniform. Moreover, as the joining surface (interface surface), the side faces of the opposing end plates 50a and 50b to which the first and second heating platens 5 and 6 are pressed are already dried to a moisture content suitable for joining. Therefore, heat from the first and second heating platens 101 and 102 of the heat press 100 is advantageously transferred to the interface with the center 51 via the surfaces of the opposing end plates 50a and 50b to satisfactorily bond between them. By doing so, a plywood (laminated plate) 52 can be obtained as shown in FIG.

In the above-described manufacture of the plywood 52, the water content of the opposing end plates 50a and 50b is substantially the same as the whole, and the nonuniformity of the water content is substantially the same when superimposed on the center 51. This is because the same parent veneer 50 was prepared by dividing in terms of thickness. As a result, the water content of the opposite end plate 50a portion and the opposite end plate 50b portion located symmetrically with respect to the center is substantially the same. For example, if the moisture content of the former part is high, the moisture content of the latter part is also substantially the same as the former. Likewise, if the former has a low moisture content, the latter has also a low moisture content.

When the overlap product having such an arrangement is heated and pressurized by a heat press to complete the joining, these symmetrically located portions of the opposing end plates 50a and 50b having substantially the same moisture content decrease in water content and thus have substantially the same amount. Becomes Therefore, even if the water content of the symmetrically located portions is reduced to, for example, 30% or less to cause shrinkage in the symmetrically located portions, the amount and direction of the shrinkage in the symmetrically positioned portions is substantially the same. Although this causes tension by such shrinkage in the opposing end plates 50a and 50b, this tension in the plywood 52 is symmetrically balanced with respect to the center 51. Therefore, in general, the plywood 52 is practically not twisted.

When the end plate 50 is heated and pressurized for about 30 seconds to about 1 minute by the heat dryer 1 as the first heater as described above in the embodiment in which the end plate 50 is made of Radiata Pine, the thickness direction The inner part of the furnace is dried to have a higher water content than the fiber saturation point at which shrinkage begins. However, depending on the type of wood from which the veneer is made, or even the same type of wood, the moisture content of the veneer produced by drying varies greatly depending on the thickness of the veneer or the moisture content of the veneer. Therefore, in some cases, the heating and pressurization times must be changed.

The heating and pressing time in such a case is determined as follows.

The same kind and size of the end plate to be dried by heating and pressurization were produced. Absolutely dry end plate while measuring the weight of the end plate at the same temperature under the same pressure as in the above embodiment, for example 15 seconds, 30 trillion, 45 seconds, 1 minute, 1 minute 15 seconds ... It heated and pressed using the 1st and 2nd heating platen 5 and 6 until it reached conditions. Then, the moisture content at the time of weighing was calculated based on the absolute dry amount. As the heating and pressing time by the first heater, it is preferable to select a period of 15 to 30 seconds shorter than the time when the water content of the end plate reaches 30%, which is a typical fiber saturation point of the fiber. This is because if the moisture content reaches 30%, the inner portion of the end plate in the thickness direction may also reach 30%. If heating and pressing ends 15-30 seconds before this time, the moisture content of the inner part of the end plate is certainly above the fiber saturation point. The resulting end plates are substantially flat. This results in a smooth transfer of the end plate, which provides a desirable result in the division by the divider 30.

Of course, you may select a short cycle such as 45 seconds or 1 minute, which is shorter than the time when the water content reaches 30%. If this short cycle is chosen, the moisture content of the inner portion is greater than the fiber saturation point. This is good in view of division by the divider 30. However, it is preferable to dry the end plates so that the moisture content on the surface is low, because the low moisture content enables continuous bonding operation in a short time. Overall, cycle selection is discussed in the preceding paragraph.

In the measurement of the moisture content, an electric moisture meter may be used. As in the above selection, the period may be selected based on this measurement result.

Hereinafter, a second embodiment of the present invention will be described.

In the first embodiment, the heating and pressing time of the end plates by the first and second heating platens 5 and 6 as the first heater are selected by the above-described method. However, in some end plates, if drying by heating and pressing is performed for a time shorter than necessary for bringing the moisture content inside the end plate in the thickness direction to the fiber saturation point, the surface portion of the end plate is perpendicular to the fiber direction. There is a possibility of having a moisture content that can reduce the area of the single plate.

When such end plate 50 is divided into opposing end plates 50a and 50b and bonded to the center 51 with an adhesive as in the first embodiment, the resulting plywood is likely to be warped. The reason for this can be thought of as follows.

As described above, when the end plate 50 is heated, pressurized with the first and second heating platens 5 and 6 and dried, controlling the first and second heating platens 5 and 6 to have the same temperature. It is difficult, and even for the same heating platen, it is difficult to deliver an almost perfectly uniform temperature across the heating platen. Therefore, the upper and lower surfaces of the heated and pressurized end plate 50 tend to have different moisture contents.

As a result, when the water content of the upper and lower surface portions of the end plate 50 is lower than the fiber saturation point, the shrinkage of the upper and lower surface portions is different in quantity even if the end plates are substantially flat in overall. If under these conditions, the end plate 50 is divided into opposing end plates 50a and 50b, and the opposing end plates 50a and 50b are overlapped on the center 51 by the contracted surface and the adhesive contacting the center 51 and the hot press. When the furnace is heated and pressurized, the opposing end plates 50a and 50b are joined to the center 51 by removing the adhesive, and further shrink by drying by heating with a heat press. It is difficult to determine which of the shrinkage of the adhesive and the end plate by heating is faster or whether this shrinkage occurs at the same time. However, since the shrinkage of the adhesive is faster, the water content of the surface portions of the opposing end plates 50a and 50b bonded to the center 51 is 13% to 15%, respectively, and the former and the latter are 7% to 7% by heating with a heating press. It is considered to be dried at 5%. (For this connection, the low moisture content veneer tends to be less sensitive to drying. So even in the first veneer containing different moisture, the moisture eventually tends to converge.) 50a and 50b will be reduced to amounts corresponding to a 6% and 5% reduction in moisture content, respectively. Of course, the amount of this reduction is different. In other words, the reduction is not a symmetrical balance with respect to the center 51. In practice, this can cause distortion. On the other hand, when the counter veneers (50a, 50b) dried by the moisture content gradually absorbs moisture in the air to become a water content of about 15%, which is the normal equilibrium moisture content, the counter veneers (50a, 50b) has a moisture content of 15% The area is increased prior to joining by the amount corresponding to the difference of 2% and 5%, which is the difference of 13% and the difference of 15% and 10%. As a result, the area extension is not a symmetrical balance with respect to the center 51. This also causes distortion.

The second embodiment can further reduce the occurrence of distortion of the plywood, and is performed as follows.

Although the pressure drier 1 and the divider 30 are used as in the first embodiment, a period of time for heating and pressing the end plate by the first and second heating platens 5 and 6 of the pressure drier 1 Is selected as follows.

As in the first embodiment, a single plate of the same type as that of the single plate to be made of wood of the same type and to be dried by heating and pressing was manufactured. First, the initial area of the end plate was measured accurately in the direction perpendicular to the fiber direction. The prepared end plates were then measured at 15 second intervals in the direction perpendicular to the fiber direction, measuring the area of the end plate 50 in the same conditions as in the first embodiment, for example, 15 seconds, 30 seconds, 45 seconds, 1 minute, 1 minute 15. It heated and pressed with the 1st and 2nd heating platen 5 and 6 for the second. From the measured area, record the time when the area of the end plate is initially smaller than the initial area. A time period of about 30 seconds (including an allowable error) shorter than the recorded time is selected as a time for heating and pressing by the first heater. The end plate 50 was dried by the pressure drier 1 as a first heater for a selected time period and then divided by the divider 30 as in the first embodiment to produce opposing end plates 50a and 50b. As in the first embodiment, the plywood 52 was manufactured by performing a continuous process using the heat press 100. In this example, heating and pressurization were performed for about 6 minutes.

As a result, even if the water content in the upper and lower surface portions of the end plate 50 dried by the pressure drier 1 is different, the end plate is substantially flat, thereby being virtually distorted. Furthermore, in order to obtain the plywood 52, the end plate 50 is divided into the opposing end plates 50a and 50b by the divider 30, the opposing end plates are superimposed on the center 51, and the product is heated as a second heater. Heating by the first and second heating platens 101 and 102 of 100). The plywood 52 thus obtained becomes less warped compared with the plywood in the first embodiment. Moreover, if the opposing end plates 50a, 50b gradually absorb the moisture in the atmosphere so that the moisture content is about 15%, which is usually the equilibrium moisture content, the plywood is less warped compared to the plywood in the first embodiment.

The embodiment of the present invention has been described above. However, the following correction may be made.

(1) In Example 1, a three-ply plywood was produced with a moisture content suitable for bonding as a whole. You may modify this as follows. As shown in Fig. 6, the non-drying center 52 has an upper and a lower surface with grooves 54, each groove extending in the fiber direction and having a width of about 1 mm and a depth of about 2 mm. The grooves 54 on the upper surface and the grooves 54 on the lower surface are located at intervals of about 50 mm so as to cross each other in a direction perpendicular to the fiber direction at intervals of about 25 mm. As in the drying of the plywood 50 in the first embodiment, the center 53 is heated by the pressure drier 1 between the first and second heating platens 5 and 6 under the same conditions for 1 minute. Pressurized. In such heating and pressurization, moisture near the upper and lower surfaces of the center 53 evaporates, and steam passes through the grooves 21 and 22 of the heating platens 5 and 6 and the grooves 54 of the center 53. Is released. Thereby, compared with the case where the groove | channel 54 is not provided, the upper and lower surface parts of the center 53 are dried on the conditions suitable for joining in a short time.

On the other hand, opposing end plates 50a and 50b were manufactured by the pressure drier 1 and the divider 30 as in the first embodiment. Urea resin adhesive was added to the upper and lower surfaces of the center 53 not dried. On the center 53, the opposing end plates 50a and 50b were superimposed so that the grains of the opposing end plates 50a and 50b may mutually correspond mutually. The opposing end plate 50a, the center 53, and the opposing end plate 50b thus superimposed were heated and pressurized by a heat press 100 in which pressure and temperature were set at 5 kg and 150 ° C. per square centimeter of the end plate, respectively. .

By using this procedure, not only the surfaces of the opposing end plates 50a and 50b to be bonded, but also the surface of the center 53, that is, all surfaces to be bonded, were dried by the pressure drier 1. As a result, joining was satisfactorily performed. Furthermore, in the heating and pressurization by the heat press 100, the moisture still contained in the opposing end plates 50a and 50b and the moisture contained in the center 53 evaporate, and the generated vapors are respectively formed in the first and second heating platens ( Through 101,102 and through groove 54.

Thus, the resulting plywood is hardly distorted. Moreover, even if the center 53 is not sufficiently dried, moisture in each layer is easily released. This makes it possible to dry the center in a short time before the joining step.

(2) In the above, the Example which manufactured the 3-ply plywood was demonstrated. When manufacturing a 5-ply plywood, the procedure is as follows.

As shown in Figs. 7 and 8, opposing end plates 56a and 56a, cross-bands 57a and 57b and center 58, each having a length of about 1800 mm and a width of about 900 mm, were used. In this connection, the width of each crossband is 900 mm in the direction perpendicular to the fiber direction. Prior to division, opposing end plates 56a and 56a, cross bands 57a and 57b, a single plate having a thickness of about 3.4 mm as a pre-division measurement, and a single plate having a thickness of about 4.4 mm as a pre-division measurement were used, respectively. In the same manner as in the above embodiment, each of the mother end plates having the upper and lower surfaces was dried by the pressure dryer 1 as the first heater and then divided by the divider 30. As a result, two pairs of single plates (all: four single plates) were produced.

As shown in Fig. 8, the thickness is about 3.4 mm, and the upper and lower surfaces have grooves 59 extending in the fiber direction, respectively, and the centers 58 having the same size are the grooves of the center 53 shown in FIG. Located at the same interval as Then, the upper and lower surfaces of the center 58 were dried by the pressure drier 1 as a 1st heater under the conditions similar to the said Example.

Thereafter, urea resin adhesive was applied to both surfaces of each of the cross bands 57a and 57b. On the center 58, the cross bands 57a and 57b were superimposed so that the surfaces of the cross bands 57a and 57b dried by the pressure drier 1 abut and the grains substantially coincide with each other. The resultant three-ply intermediates were further superimposed on the opposite single plates 56a and 56a such that the faces of the opposite single plates 56a and 56a to be dried under conditions suitable for bonding were in contact with the three-ply intermediates and the grains substantially coincide with each other.

The products of the five layers thus superimposed were heated and pressurized for about 10 minutes by means of a heat press 100 in which pressure and temperature were set at 8 kg and 150 ° C. per square centimeter of the single plate, respectively.

By this procedure the moisture in the center 58 and the moisture in the crossbands 57a and 57b were evaporated and released through the grooves 59 provided in the center 58 and the moisture in the opposing end plates 56a and 56a was evaporated. Was discharged through the grooves 21 and 22 of the first and second heating platens 101 and 102 of the pressure dryer 1. As a result, joining was satisfactorily performed. Thus, 5-ply plywood was obtained.

In this junction, for opposing end plates 56a and 56a and crossbands 57a and 57b, which are symmetrically positioned with respect to center 58, respectively, the symmetrically positioned portions are substantially the same texture and substantially the same. Has moisture content. Therefore, as in the plywood obtained in the above embodiment, even if the end plate and the adhesive shrink due to heating and pressure for bonding, the obtained plywood is generally substantially free of distortion. Moreover, even if one or several layers contain large amounts of moisture, the moisture in each layer is easily released. Therefore, it is possible to significantly prevent the occurrence of so-called punctures in bonding failure. Moreover, since the heating and pressure for joining can also be used for drying of the center, the predrying step can be performed in a short time.

If urea resin adhesives are used to bond the layers, there is a possibility of formalin leaking out of the resulting plywood causing practical problems. However, if the center is provided with the modified embodiment in the modified embodiment (1) and the modified embodiment as described above, in the case of performing the heating and pressure for joining, and in the case of forming the resulting plywood after manufacturing, Grooves can release formalin gently.

(3) In each Example mentioned above, the pressure drier 1 is used as a 1st heater. Instead, a heat press generally used in layer bonding, i.e., a heat platen having no groove on the pressurized surface, may be used. In this pressurization, a heating platen without a groove on the pressurizing surface is pressed against the end plate. However, by releasing the pressure of the hot press, for example about every 30 seconds, steam generated from pressurization is released to prevent damage to the end plate. Instead, by pressurizing the heating platen against the end plate with a wire netting inserted between the end plate and each heating platen, it is possible to release the vapor emitted from the end plate through the gap provided in the gold plate. This eliminates the need to release the pressure of the hot press.

Furthermore, such a conventional hot press may be used instead of the hot press 100 as the second heater. In this case, the pressure of the heating press is likewise released every about 20 seconds. However, once the vapors are virtually gone, they are no longer needed. Thereafter, the heating platen may be continuously pressed against the end plate until the adhesive is sufficiently removed. When pressurizing with a gold mesh inserted between the heating platen and the end plate, the need to release the pressure of the heating press is also eliminated.

(4) In the manufacture of the 5-ply plywood described in the modification example (2), the opposing end plates 56a and 56a, the cross bands 57a and 57b, and the center 58 are overlapped with an adhesive, and one heating Bonding of this layer is performed by a press action. However, the 5-ply plywood may be produced as follows.

The center 58 is dried in a conventional drying apparatus to bring the overall moisture content to about 10% suitable for bonding. The adhesive is then applied to both sides of the center 58. To produce cross-bands 57a and 57b, respectively, the end plates having a thickness twice thereof are dried by a pressure drier 1 as a first heater and divided by the divider 30 as in the embodiment in the modified embodiment (2). It has an upper and lower surface divided by). The cross bands 57a and 57b thus manufactured are in contact with the center 58 by the pressure dryer 1 and are substantially symmetrical with respect to the grain center 58 of the cross bands 57a and 57b. To coincide, they overlap on the center 58. Thereafter, the opposing end plates 56a, 56a and the center 58 are heated and pressurized by the heat press 100 as a second heater, which is set at a pressure and a temperature of 8 kg and 150 ° C per square centimeter of the end plate, respectively. The 3-ply plywood was produced by completing this.

Moreover, in order to manufacture the opposing end plates 56a and 56a, respectively, the end plate which is double in thickness has the upper and lower surfaces which were dried by the pressure drier 1 as a 1st heater, and divided by the divider 30. As shown in FIG. The opposite end plates 56a and 56a thus produced are superimposed on the 3-ply plywood so that the surface dried by the pressure dryer 1 contacts the 3-ply plywood and the grains of the opposing end plates 56a and 56a substantially coincide with each other. Then, 5-ply plywood was produced by heating and pressurizing the overlapped layers by a heat press 100 as a second heater, which was previously set at 8 kg and 150 ° C. in pressure and temperature for 1 square centimeter of single plate, respectively. .

In this procedure, the opposing end plates 56a and 56a were joined to the center 58 to produce a 3-ply plywood. In the 3-ply plywood, the portions of the crossbands 57a, 57b located symmetrically about the center have the same moisture content. Therefore, even if the end plate is shrunk by the heating and pressure for joining, the three-ply plywood is practically not distorted for the same reason as described in the above embodiment. Furthermore, if the opposite end plates 56a and 56a are heated and pressurized to form a three-ply plywood that is substantially free from distortion causing shrinkage of the opposite end plate, the opposite end plates 56a and 56a symmetrically positioned with respect to the center 58. The texture and moisture content of the parts will be substantially the same. Therefore, even when the opposite end plate is distorted by the heating and pressure for bonding, the produced plywood is generally not substantially distorted for the same reason as described in the above embodiment.

When the water content of the center 58 is high, it is preferable to provide a groove in the center as indicated by the reference numeral 59 of FIG.

In order to manufacture the plywood of seven or more layers, one or more pairs of opposing single-plates can be bonded to a 5-ply plywood one by one by the same method as the manufacture of such 5-ply plywood from a 3-ply plywood.

(5) Examples of manufacturing the single plate were described. However, in an LVL consisting of a plurality of single plates in which all or almost all single plates overlap with their fibers in the same direction, where the plywoods can be symmetrically overlapped with respect to the centerline in the thickness direction and joined in symmetrically overlapping conditions As in, the opposite end plate is manufactured by drying the end plate by the pressure dryer 1 as the first heater and dividing the end plate dried by the divider 30.

(6) In the above embodiment, prior to the division in the thickness direction, the upper and lower surfaces of the end plate are dried by a heating platen for a short time, and only the surface portion of the end plate is dried under predetermined conditions. However, the upper and lower surfaces of the end plate may be dried by blowing hot air thereon as a first heater.

(7) Urea resin adhesive which is a thermosetting adhesive agent is used as an adhesive agent in the said Example. However, as long as the adhesive such as melamine resin adhesive is a thermosetting adhesive, other adhesive may be used. The adhesive may be in the form of a sheet placed between layers and removed by heating to bond.

(8) In the said Example, a single plate is used as a center. However, the center may be a wood board such as a fiber board or a particle board. In other words, any board may be used as long as the board can be bonded to a single board.

(9) In the above embodiment, a blade is used as a divider for dividing the end plate in the thickness direction. However, the end plate may be divided into an endless file saw of a band sawing machine. Alternatively, the end plates can be divided into thin (less thick) steel bends, which are looped to form one end with an endless continuous edge and the file saw is operated in a file cutter. It is supposed to move when you do.

(10) In the above embodiment, the heating platen is used as the first and second heaters. Alternatively, a single plate having an upper and lower surface to be dried or a layer to which an adhesive is applied may be passed between a plurality of opposing heating roll pairs spaced at appropriate intervals for heating and pressing the upper and lower surfaces.

As described above, according to the present invention, even if a single plate of one kind of wood, in which significant warping or the like occurs due to drying, can be properly delivered after the single plate is dried, it is preferable to manually or mechanically overlap the opposite single plate with the above-described symmetry. It is possible. Therefore, the problem that the yield is reduced and the quality of the product is deteriorated.

Claims (8)

Pressurizing the first heater to the upper and lower surfaces of the end plate for a predetermined time to perform proper drying; Dividing the end plate into two opposing end plates by thickness unit by a suitable divider; Arranging the wood planks between the opposing end plates by an adhesive such that the surfaces resulting from the division are disposed on the outer surface such that the grains of the opposing end plates substantially coincide with each other; A method for producing a laminated sheet, comprising the step of pressing the second heater against the surface formed by dividing to bond the opposing end plate and the wood plank. The method according to claim 1, wherein the time period for pressurizing the first heater against the end plate is shorter than the time period just enough for drying by heating and pressing, and the moisture content of the inner part in the thickness direction is dried by heating and pressing. Laminated plate manufacturing method characterized by taking to the fiber saturation point. The method of claim 1, wherein the time period for pressing the first heater against the opposing end plate is shorter than the cycle time for starting the end plate to contract in a direction perpendicular to the fiber direction. The method for manufacturing a laminate according to any one of claims 1 to 3, wherein the first heater is a heating platen. The method for manufacturing a laminate according to any one of claims 1 to 3, wherein the second heater is a heating platen. 4. A method according to any one of the preceding claims, wherein the first heater is a heated platen having a pressurized surface having a plurality of vapor release grooves each extending from one end to the other of the pressurized surface. 4. A method according to any one of the preceding claims, wherein the second heater is a heated platen having a pressurized surface having a plurality of vapor release grooves extending from one end to the other of the pressurized surface, respectively. The method according to any one of claims 1 to 3, wherein the divider is a blade.