JP7227649B1 - Multistage transfer type hot air dryer - Google Patents

Abstract

[Problem] In a ventilation area of a circulation air passage, a means for discharging dust such as small and light pieces of wood and wood powder is provided in the ventilation duct in addition to hot air ejection holes, so that small and light dust adheres to the inside of the ventilation duct. - To provide a multi-stage conveying hot-air drying apparatus that can suppress deposition and make clogging of ejection holes difficult to occur. SOLUTION: In a ventilation area P1 of each stage, hot air A1 flowing inside upper and lower jet boxes 21, 22 in a ventilation direction is ejected from ejection holes 21c2, 22c2 to the outside of the box, and transported along a corresponding transport path Q. While the veneer veneer W transported in the direction is dried from both upper and lower sides, part of the flow is decelerated by the reflecting members 21d1 and 22d1 and the direction is changed to flow out of the box through the through holes 21d2 and 22d2. [Selection drawing] Fig. 8

Description

TECHNICAL FIELD The present invention relates to a multi-stage conveying hot air drying apparatus (also referred to as a veneer dryer) used for drying veneer plate materials such as veneer veneers.

In the above-mentioned veneer dryer, conveying paths for horizontally conveying a plurality of rows of veneer sheet materials in parallel are provided in multiple stages, and the veneer sheet materials on each stage during transportation are dried by being blown with hot air. Furthermore, like the veneer dryers shown in Patent Documents 1 and 2, the upper and lower multistage conveying paths are divided into a plurality of heating sections perpendicular to the conveying direction, and hot air is supplied to each heating section to dry the veneer sheet material in each stage. A hot air horizontal circulation system that forms a circulation air passage that circulates in a direction orthogonal to the conveying direction is often adopted.

Specifically, the circulation air passage of the hot air horizontal circulation system includes, for example, a ventilation area, a gathering area, a return area, and a distribution area as shown below.
・Ventilation area: Upper and lower ventilation ducts that circulate hot air along the ventilation direction parallel to the plywood plate material on each level and have blowout holes that blow hot air to the upper and lower surfaces of the plywood plate material. (jet box) and formed for each stage.
Collective area: The downstream side of the ventilation area of each stage in the ventilation direction is communicated vertically, and a single circulation fan is arranged in the upper part to suck the exhaust air from the ventilation area of each stage.
Return area: Return air from the circulation fan traverses above the uppermost conveying path in a direction opposite to the airflow direction, and flows into the heater arranged opposite the circulation fan.
・Distribution area: The hot air heated by the heater flows downward and is distributed and supplied to the upstream side of the ventilation area of each stage in the ventilation direction.

In addition, the return area is connected to a discharge air passage for discharging part of the returning air (high-humidity air) directed from the circulation fan to the heater into the atmosphere. intake is provided).

In the circulation air passage of the above-described hot air horizontal circulation system, it is difficult to prevent dust such as wood chips, wood powder, etc., separated from the veneer plate material conveyed for hot air drying, from being mixed. However, among these, large garbage that has separated from the plywood board material immediately after drying can be sorted and collected, for example, by weight sorting based on the difference in specific gravity in the gathering area. On the other hand, some of the relatively small and light dust is ejected with hot air from the blowout holes in the ventilation area and adheres to the surface of the plywood board (such dust is dry, so the plywood is discharged). It can be easily removed from the plate material), but the residue is difficult to separate and collect in any area, and there is a high possibility of repeated circulation (co-rotation) in the circulation air passage.

As this circulation is repeated, small and light dust gradually begins to accumulate inside the ventilation duct, and if it adheres to the blowout hole in particular, it will cause clogging, reducing the efficiency of hot air drying in the ventilation area. do. Furthermore, in order to remove small and light dust accumulated inside the ventilation duct, regular or temporary maintenance work must be performed for a long time and with high frequency, resulting in an increase in maintenance costs. In addition, when installing a filter or net for collecting small and light dust in any area of the air circulation path, the equipment cost and replacement cost when adopting a high performance filter with excellent collection rate In addition, an increase in suction resistance may lead to a deterioration in flowability, resulting in a decrease in the efficiency of hot-air drying.

Japanese Patent No. 3953704 (Fig. 2) Japanese Patent No. 6679034 (Fig. 2)

An object of the present invention is to provide a ventilation duct with means for discharging small and light dust such as wood chips and wood powder in addition to hot air ejection holes in the ventilation area of the circulation air passage, so that small and light dust can be removed from the inside of the ventilation duct. To provide a multi-stage conveying hot air drying apparatus capable of suppressing the adhesion and accumulation of dust particles and preventing the clogging of ejection holes or the like.

Means for solving the problem and effects of the invention

In order to solve the above problems, the multistage conveying hot air drying apparatus of the present invention includes:
Conveyance paths for horizontally conveying multiple rows of veneer sheets in parallel are provided in multiple stages, and a hot air circulation air path is provided in a vertical cross section that intersects (for example, perpendicularly) the conveying direction of the veneer sheet materials in each stage of the conveyance path. is formed, and a multistage conveying hot air drying apparatus for drying by blowing the hot air of the circulating air passage to each stage of the plywood board being conveyed along the conveying direction,
When the vertical cross section is viewed from the front, the circulation air passage circulates the hot air along the ventilation direction parallel to the plywood plate material of each stage and blows out the hot air to the upper and lower surfaces of the plywood plate material respectively. A ventilation area formed for each stage, which is composed of upper and lower ventilation ducts (e.g., jet boxes) having ejection holes, and a downstream side of the ventilation area of each stage in the ventilation direction are vertically communicated with each other. A gathering area in which a single circulation fan is arranged in the upper part for sucking the exhaust air from the ventilation area, and the return air from the circulation fan is directed further above the uppermost conveying path in a direction opposite to the ventilation direction. A return area that flows into a heater arranged opposite to the circulation fan, and a hot air heated by the heater that flows downward and is distributed and supplied to the upstream side of the ventilation area of each stage in the ventilation direction. a distribution area for
At least one of the upper and lower ventilation ducts has a resistance member (for example, a reflector plate) disposed on the inner bottom to change the direction of the flow while applying resistance to a part of the flow of hot air flowing in the ventilation direction to decelerate it. ), and a through hole formed in one of the wall surfaces to guide the hot air decelerated and redirected by the resistance member to the outside of the duct,
In the ventilation area of each stage, the hot air flowing inside the upper and lower ventilation ducts in the ventilation direction is ejected out of the ducts from the ejection holes to vertically move the plywood board conveyed in the conveying direction along the corresponding conveying path. A part of the flow, which is dried from both sides and whose direction is changed while being decelerated by the resistance member, flows out of the duct from the through-hole.

In the multi-stage conveying hot air drying apparatus of the present invention, the ventilation duct is provided with means for discharging dust such as small and light pieces of wood and wood powder in addition to the hot air ejection holes in the ventilation area of the circulation air passage. As described above, the discharge means mainly consists of a resistance member that gives resistance to a part of the flow of hot air and promotes deceleration and direction change, and the hot air that has been decelerated and changed direction by the resistance member and is discharged out of the ventilation duct. It is composed of a through hole for outflow. By providing such a discharge means in the ventilation duct, when part of the hot air is decelerated by the resistance member and the flow direction (that is, the airflow direction) is changed and flows out from the through hole, it is small and light. Debris tends to separate from the hot air and fall down the air duct (and accumulate on the bottom of the heating section or adhere to the surface of the plywood).

In this way, most of the small and light garbage that circulates in the circulation air passage with the hot air without being ejected from the ejection hole is separated from the hot air by the above-mentioned discharge means (that is, the resistance member and the through hole), and is sorted and collected. becomes possible. As a result, the adhesion and accumulation of small, light dust inside the ventilation duct is suppressed, making clogging of the ejection holes less likely to occur, and the efficiency of hot air drying in the ventilation area is maintained for a long period of time, improving the operating rate. contribute to Furthermore, regular or temporary maintenance work can be performed in a short time and at a low frequency in order to remove small and light dust accumulated inside the ventilation duct, thereby reducing maintenance costs. Of course, there is no need to equip the circulation air passage with an expensive filter for collecting small and light dust.

For example, the following types can be practically used as the method for conveying the veneer plate material.
(1) A roll conveying type in which a plywood sheet is conveyed by sandwiching it between upper and lower roll sets arranged in multiple sets. (See FIG. 6 of Patent Document 1)

Further, in order to solve the above problems, the multistage conveying hot air drying apparatus of the present invention includes:
A transport path in which multiple sets of feeding rolls consisting of long upper rolls and lower rolls are arranged at predetermined intervals, and multiple rows of veneer sheets are horizontally transported in parallel while being sequentially sandwiched between the upper and lower rolls of each set. are provided in upper and lower multiple stages, and hot air circulation paths are formed in the vertical cross section perpendicular to the conveying direction of the plywood material in each stage of the conveying path, and the plywood material on each stage being conveyed along the conveying direction On the other hand, a multistage conveying hot air drying device for drying by blowing hot air in the circulation air passage,
When the vertical cross section is viewed from the front, the circulation air passage circulates the hot air along the ventilation direction parallel to the plywood plate material of each stage and blows out the hot air to the upper and lower surfaces of the plywood plate material respectively. A ventilation area formed for each stage, which is composed of upper and lower ventilation ducts (e.g., jet boxes) having ejection holes, and a downstream side of the ventilation area of each stage in the ventilation direction are vertically communicated with each other. A gathering area in which a single circulation fan is arranged in the upper part for sucking the exhaust air from the ventilation area, and the return air from the circulation fan is directed further above the uppermost conveying path in a direction opposite to the ventilation direction. A return area that flows into a heater arranged opposite to the circulation fan, and a hot air heated by the heater that flows downward and is distributed and supplied to the upstream side of the ventilation area of each stage in the ventilation direction. a distribution area for
At least one of the upper and lower ventilation ducts has a resistance member (for example, a reflector plate) disposed on the inner bottom to change the direction of the flow while applying resistance to a part of the flow of hot air flowing in the ventilation direction to decelerate it. ), and a through hole formed in one of the wall surfaces to guide the hot air decelerated and redirected by the resistance member to the outside of the duct,
In the ventilation area of each stage, the hot air flowing inside the upper and lower ventilation ducts in the ventilation direction is ejected out of the ducts from the ejection holes to vertically move the plywood board conveyed in the conveying direction along the corresponding conveying path. A part of the flow, which is dried from both sides and whose direction is changed while being decelerated by the resistance member, flows out of the duct from the through-hole.

As described above, the same effect as described above can be obtained even in the case of adopting the roll-conveying type of veneer plate material by the roll set.

Therefore, in these multistage conveying hot-air dryers, the hot air flowing in the ventilation direction is reflected by the resistance member to change its traveling direction, and the through holes are positioned in the reflection direction of the hot air as viewed from the resistance member.

In this way, the hot air that has been reflected by the resistance member to change its traveling direction flows out as it is from the through-hole located ahead of the reflection direction, so that small and light dusts smoothly pass through the hot-air without clogging the through-hole. separated into

In each ventilation duct, the through holes are preferably formed in a shape different from that of the ejection holes.

For example, by making the through hole rectangular or triangular and the ejection hole round, even small and light garbage can be discharged from the through hole and the ejection hole in various forms with different shapes and sizes. can. Therefore, deposition and clogging are less likely to occur in both the through holes and the ejection holes, and the amount of dust that repeatedly circulates in the circulation air passage can be reduced.

In addition, each ventilation duct is provided with a plurality of through holes and a plurality of ejection holes,
The number ratio of through holes and ejection holes is 1/100 or less in units of ventilation ducts, and the average opening area ratio of single through holes and ejection holes (that is, per hole) is 1/5 or more. It is below.

The hot air flowing out of the through-holes may carry away (discard) heat without actively contributing to the hot-air drying of the veneer board like the hot air blowing out of the ejection holes. However, when considering the ventilation duct as a unit, the total opening area of the through holes is at most 5/100 (5%) of the total opening area of the ejection holes, so the heat loss (waste heat amount) in hot air drying is minimized. can be kept in

Of the upper and lower ventilation ducts, the lower ventilation duct located below the veneer plate is formed in a rectangular or pseudo-rectangular cross section perpendicular to the ventilation direction,
The hot air flowing through the ventilation duct blows out of the duct from the blowout hole formed in the ceiling wall to dry the lower surface of the plywood board.
The resistance member is fixed to the bottom wall in such a manner that it obliquely intersects with the airflow direction in a plan view so as to approach one of the side walls toward the downstream side. open to
The hot air flowing through the bottom of the lower ventilation duct is decelerated by the resistance member and is redirected so as to approach one of the side walls, and flows out of the duct through the through hole.

A portion of the hot air flowing through the lower ventilation duct is decelerated by a resistance member fixedly arranged on the bottom wall portion and is redirected from the ventilation direction, and flows out from the through hole opened in one of the side wall portions. In doing so, the entrained small and light debris separates from the hot air, falls down the ventilation duct and is discharged, and is deposited, for example, on the bottom of the heating section. As a result, adhesion and accumulation of small and light dusts to the inside of the lower ventilation duct are suppressed, and clogging of the ejection holes and through holes is less likely to occur. Furthermore, in order to remove small and light dust accumulated inside the lower ventilation duct, regular or temporary maintenance work can be performed in a short time and at a low frequency, thereby reducing maintenance costs.

Of the upper and lower ventilation ducts, the upper ventilation duct located above the plywood plate is formed in a pseudo-rectangular cross section perpendicular to the ventilation direction,
On the bottom wall of the upper ventilation duct, reinforcing ribs (for example, triangular in cross section) are formed along the ventilation direction between rows of ejection holes arranged in a plurality of rows along the ventilation direction and on both sides of the rows. ,
The resistance members and through holes are located in the reinforcing ribs.

By arranging the resistance member and the through hole using the reinforcing ribs of the upper ventilation duct in this way, it is possible to easily and inexpensively construct a small and light waste discharge structure.

Hot air flowing through the upper ventilation duct blows out of the duct from ejection holes formed in the bottom wall to dry the upper surface of the plywood board.
The resistance member is fixedly arranged between the rows of the ejection holes in the bottom wall portion in such a manner that the reinforcing ribs are widened in a V-shape in the airflow direction in a plan view so as to approach both side wall portions toward the upstream side. , the through-hole opens at a gathering portion sandwiched between the V-shaped resistance members in the bottom wall,
A part of the hot air flowing through the bottom of the upper ventilation duct flows inside the reinforcing ribs located between the rows of the blowout holes, is decelerated by the resistance member, is changed in direction to the collecting part, and flows out of the duct through the through hole. It reaches the upper surface of the near plate.

A part of the hot air flowing through the upper ventilation duct is decelerated by a resistance member fixedly arranged between the rows of blowout holes on the bottom wall, and the direction is changed from the ventilation direction to the collecting part, and is opened to the collecting part on the bottom wall. flow out from the through-holes. At that time, the mixed small and light contaminants are separated from the hot air, fall below the ventilation duct, adhere to the upper surface of the veneer plate material, and are discharged. As a result, adhesion and accumulation of small and light dusts to the inside of the upper ventilation duct is suppressed, and clogging of the ejection holes and through holes is less likely to occur. Furthermore, in order to remove small and light dust accumulated inside the upper ventilation duct, regular or temporary maintenance work can be performed in a short time and at a low frequency, thereby reducing maintenance costs.

FIG. 2 is a side view schematically showing a multi-stage conveying hot-air drying apparatus for plywood. FIG. 2 is a front sectional view of FIG. 1; The perspective view which shows typically conveyance of the veneer board material by a feed roll set. FIG. 3 is a front cross-sectional view schematically showing the feed roll set of FIG. 2 ; 5 is a right side view of FIG. 4; FIG. FIG. 3 is a front partial cross-sectional view schematically showing the jet box assembly of FIG. 2; Fig. 3 is a perspective view of the upper jetbox; Fig. 3 is a perspective view of the lower jetbox; FIG. 4 is a perspective partial enlarged cross-sectional view of the upper jet box for explaining the first collecting portion; FIG. 4 is a perspective partial enlarged cross-sectional view of the upper jet box for explaining the second collecting portion; FIG. 11 is a perspective partial enlarged cross-sectional view of the upper jet box for explaining the third collecting portion; Partially enlarged cross-sectional view of the upper jet box. Planar partial enlarged view of the lower jet box. Partially enlarged side view of the lower jet box. FIG. 14 is a partially enlarged plan view of the lower jet box showing a modification of FIG. 13;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings.

As shown in FIGS. 1 to 3, the multi-stage conveying hot-air drying apparatus 1 of this embodiment has a plurality of heating sections 2 arranged along a conveying path Q for veneer single plates W (veneer plate materials). Below each heating section 2, a plurality of sets of feeding rolls 10 consisting of an upper roll 11 and a lower roll 12 having a long length (roll length of about 3 to 6.5 m) are arranged at predetermined intervals. Conveyance paths Q are provided in multiple stages (here, six stages) for horizontally transporting rows of veneer sheets W (plywood sheets) horizontally in parallel while being sequentially sandwiched between sets of upper and lower rolls 11 and 12 .

The upper and lower rolls 11 and 12 of each set forming the feed roll set 10 sandwich the veneer veneer W from both sides in the plate thickness direction and feed it while rotating. has roll shaft portions 11a and 12a at one end (left side in FIG. 4) and roll shaft portions 11b and 12b at the other end (right side in FIG. 4). The roll shafts 11a and 12a on one end side (the left side in FIG. 4) are rotatably supported on the longitudinal beam 31 via roll bearings 13a and 14a, respectively. The roll shafts 11b and 12b on the other end (the right side in FIG. 4) are rotatably supported by a casing 320 fixed to the cross beam 32 via roll bearings 13b and 14b.

An upper roll gear 13c is fixed to the tip of the roll shaft portion 11b on the other end side (the right side in FIG. 4). Similarly, a lower roll gear 14c is fixed in the middle of the roll shaft portion 12b on the other end side, and a sprocket 14d is fixed to the tip thereof. As shown in FIG. 5, the upper roll gear 13c meshes with the lower roll gear 14c through gear connection, and the sprocket 14d meshes with the roller chain 15 through chain connection. As a result, the rotational driving force of a drive motor (not shown) is transmitted to the upper and lower rolls 11 and 12 via the roller chain 15, sprocket 14d, lower roll gear 14c and upper roll gear 13c, respectively. A veneer W is sent out in the conveying direction.

As shown in FIG. 1, the feeding roll set 10 (upper and lower rolls 11, 12) in the conveying path Q of each stage is provided between the adjacent roll set 10 and a jet box having substantially the same length as the upper and lower rolls 11, 12. A set 20 (ventilation duct set) is arranged. The jet box set 20 includes an upper jet box 21 (upper duct) horizontally adjacent to the upper roll 11 and a lower jet box 22 (lower duct) horizontally adjacent to the lower roll 12, each corresponding to It is arranged at the upper and lower positions sandwiching the conveying path Q which

As shown in FIG. 6, the upper and lower jet boxes 21 and 22 have openings 21a and 22a at upper and lower roll shaft portions 11a and 12a, which are one end sides (left side in FIG. 6), and are gradually opened and cut along the roll shaft direction. A cross section that reduces the area forms a rectangular ventilation passage. The upper and lower jet boxes 21 and 22 are formed as tip wall portions 21b and 22b that close the openings on the upper and lower roll shaft portions 11b and 12b on the other end side (the right side in FIG. 6) and are non-opening portions.

As shown in FIGS. 7 and 8, cutout holes 21b1 and 22b1 and open/close lids 21B and 22B capable of closing the cutout holes 21b1 and 22b1 are provided in the tip wall portions 21b and 22b. The opening/closing covers 21B and 22B can be slid up and down by rotating set screws 21B1 and 22B1 combined with compression coil springs, and the notches 21b1 and 22b1 can be opened by the sliding movement. By opening the cutout holes 21b1 and 22b1 at the time of maintenance or the like, it is possible to remove dust such as wood chips that have flowed into the upper and lower jet boxes 21 and 22 and remained.

As shown in FIG. 7, the bottom wall portion 21c of the upper jet box 21 is formed along the longitudinal direction of the upper jet box 21 with a protruding wall portion 21c1 having a substantially triangular cross section and protruding toward the transport path Q side. (FIG. 7 illustrates a case where there are four projecting wall portions 21c1). Further, a plurality of ejection holes 21c2 for blowing hot air A1 to the surface of the veneer veneer W are formed in a flat portion of the bottom wall portion 21c where the projecting wall portion 21c1 is not formed. The hot air A1 supplied from the opening portion 21a is blown onto the surface of the veneer veneer W through the ejection holes 21c2 while heading toward the tip wall portion 21b.

As shown in FIG. 8, the ceiling wall portion 22c of the lower jet box 22 is formed along the longitudinal direction of the lower jet box 22 with a protruding wall portion 22c1 having a substantially triangular cross section and protruding toward the transport path Q side. (FIG. 8 illustrates a case where there are four projecting wall portions 22c1). A plurality of ejection holes 22c2 for blowing hot air A1 to the back surface of the veneer single plate W are formed in a flat portion of the ceiling wall portion 22c where the projecting wall portion 22c1 is not formed. The hot air A1 supplied from the opening 22a is blown to the rear surface of the veneer veneer W through the ejection holes 22c2 on its way to the tip wall 22b.

Here, the ejection holes 21c2 and 22c2 are formed in a small hole shape, but in addition to or instead of this, a plurality of holes having other shapes, for example, elongated slit-like holes may be formed.

As shown in FIG. 6, the lower jet box 22 is attached at one end (left side in FIG. 6) to the longitudinal beam 31 by means of a bracket 25 connected to the top of the opening 22a. On the other hand, the upper jet box 21 is installed such that a bracket 26 connected to the lower part of the opening 21a is placed on a bracket 25 at one end (left side in FIG. 6). This placement is carried out by securing a space between the lower jet box 22 and the upper jet box 21 to form the transport path Q of the veneer veneer W. As shown in FIG. Also, the lower jet box 22 is attached to the cross beam 32 via a bracket 27 connected to the lower part thereof on the other end side (the right side in FIG. 6). On the other hand, on the other end side (right side in FIG. 6), the upper jet box 21 supports both casings 320 supporting the upper and lower rolls 11 and 12 on both sides in the conveying direction (front and back in the depth direction in FIG. 6). It is attached via a bracket 28 .

Further, as shown in FIGS. 7 and 8, each of the upper and lower jet boxes 21 and 22 changes the direction of the flow while applying resistance to a part of the flow of the hot air A1 flowing in the ventilation direction to decelerate it. Reflecting members 21d1 and 22d1 serving as resistance members disposed on the inner bottoms 21C and 22T (see FIGS. 12 and 14) for this purpose, and the hot air A1 whose direction is changed while being decelerated by the reflecting members 21d1 and 22d1 is directed outside the box. It has through holes 21d2 and 22d2 formed in one of the wall surfaces for leading out (to the outside of the jet boxes 21 and 22). The details of the reflecting members 21d1 and 22d1 and the through holes 21d2 and 22d2 in this embodiment will be described later.

By the way, in each heating section 2, as shown in FIG. 2, a circulation air path P for hot air A1 is formed in a vertical cross section that intersects (here, orthogonally) with the transport direction of the veneer veneer W in the transport path Q of each stage. Then, the hot air A1 of the circulating air passage P can be blown to dry the plywood veneer W on each stage being conveyed along the conveying direction. As described above, the multi-stage conveying hot-air drying apparatus 1 of this embodiment supplies hot air to the veneer single plate W (plywood plate material) by the horizontal circulation system.

When the vertical section is viewed from the front, each circulation air passage P includes a ventilation area P1, a gathering area P2, a return area P3, and a distribution area P4.

The ventilation area P1 has ejection holes 21c2 and 22c2 for circulating the hot air A1 along the ventilation direction parallel to the veneer veneer W in each stage and for applying the hot air A1 to the upper and lower surfaces of the veneer veneer W, respectively. (exhaust port) and formed by upper and lower jet boxes 21, 22 (ventilation ducts) for each stage.

The gathering area P2 vertically communicates with the downstream side of the ventilation area P1 of each stage in the ventilation direction, and includes a circulation fan 4 (in this case, a single circulation fan (blower )) is placed at the top.

The return area P3 causes the return air A3 from the circulation fan 4 to traverse above the uppermost conveying path Q in a direction opposite to the airflow direction and flow into the heater 3 arranged opposite the circulation fan 4 . The heater 3 can be, for example, a heating element such as a steam pipe, an electric heater, or heat oil.

The distribution area P4 causes the hot air A4 heated by the heater 3 to flow downward, distributes it to the upstream side in the ventilation direction of the ventilation areas P1 of each stage, and supplies it.

In the circulation air passage P thus formed, as shown in FIG. 2, the hot air A4 sent out in the ventilation direction by the circulation fan 4 in the return area P3 and heated by the heater 3 is directed to the distribution area P4. reach. The hot air A4 reaching the distribution area P4 is basically blocked from moving toward the collective area P2 by the vertical beams 31 and the like, but is distributed to the upper and lower jet boxes 21 and 22 of each stage that constitute the ventilation area P1. By passing through the openings 21a and 22a on the P4 side, the air is supplied to the insides of the jet boxes 21 and 22 (ventilation area P1). The hot air A1 supplied to the insides of the upper and lower jet boxes 21 and 22 of each stage goes toward the front end walls 21b and 22b on the gathering area P2 side, and enters the conveying path Q through the ejection holes 21c2 and 22c2 while heading. Both the front and back main surfaces of the veneer veneer W conveyed on the conveying path Q are dried. The hot air A1 blown toward the transport path Q is discharged into the space P1a (which may be included in the ventilation area P1) outside the outer periphery of the upper and lower jet boxes 21 and 22, and is discharged as the exhaust air A2 of the ventilation area P1. It is sucked by the circulation fan 4 . At this time, the exhaust air A2 passes through the space P1a outside the outer periphery of the upper and lower jet boxes 21 and 22, passes through the lateral beams 32 and the casing 320 provided on the gathering area P2 side, and circulates through the gathering area P2. Reach fan 4. Then, the return air A3 is sent out through the return area P3 by the circulation fan 4, and is repeatedly circulated through the distribution area P4, the ventilation area P1, and the gathering area P2 in the same manner.

In addition, the jet boxes 21 and 22 constituting the ventilation area P1 of each stage discharge dust such as small and light wood pieces and wood powder mixed in the hot air A1 separately from the ejection holes 21c2 and 22c2 of the hot air A1. Means are provided.

As shown in FIGS. 7 and 8, this discharging means is configured to have the above-described reflecting members 21d1 and 22d1 and through holes 21d2 and 22d2. The reflecting members 21d1 and 22d1 provide resistance to part of the flow of the hot air A1 in the jet boxes 21 and 22 to promote deceleration and direction change, and the through holes 21d2 and 22d2 decelerate and change direction by the reflecting members 21d1 and 22d1. The hot air A1 subjected to the change of is flowed out of the jet boxes 21 and 22. As a result, small and light contaminants mixed in the hot air A1 can be separated. The separated dust falls below the jet boxes 21 and 22 and deposits on the bottom of the heating section 2 (on the bottom surface 2d: see FIG. 2) or adheres to the surface of the veneer veneer W. However, the dust adhering to the surface of the veneer veneer W is blown off by the hot air A1 ejected from the ejection hole 21c2 (see FIG. 6) and falls downward, and like the others, the bottom of the heating section 2 (bottom surface) 2d).

As described above, in the ventilation area P1 of each stage, the hot air A1 flowing in the ventilation direction inside the upper and lower jet boxes 21, 22 is ejected from the ejection holes 21c2, 22c2 to the outside of the box, and the corresponding transport path Q is ejected. The veneer veneer W conveyed in the conveying direction is not only dried from both upper and lower surfaces, but also partially decelerated and redirected by the reflecting members 21d1 and 22d1 inside the veneer veneer W. It flows out to the outside (the outside of the jet boxes 21 and 22). As a result, most of the dust mixed in the hot air A1 can be separated from the hot air A1 and sorted and collected.

As shown in FIGS. 9 to 11C and 13, in each of the jet boxes 21 and 22, the through holes 21d2 and 22d2 are positioned in the reflection direction of the hot air A1 when viewed from the reflecting members 21d1 and 22d1. The hot air A1 flowing in the ventilation direction is reflected by the reflecting members 21d1 and 22d1 and changes its traveling direction. outside).

Moreover, in each of the jet boxes 21 and 22, the through holes 21d2 and 22d2 are formed in a shape different from the ejection holes 21c2 and 22c2. Specifically, the through-hole 21d2 is triangular or approximately rhombus-shaped (see FIG. 9 to FIG. 11C), the through-hole 22d2 is square-shaped (see FIG. 14), and the ejection holes 21c2 and 22c2 (see FIG. 7) and FIG. 8) is circular. Note that each hole may have another hole shape.

Further, in each of the jet boxes 21 and 22, a plurality of through holes 21d2 and 22d2 and a plurality of ejection holes 21c2 and 22c2 are provided here. The number ratio of the through holes 21d2 and 22d2 and the ejection holes 21c2 and 22c2 in units of the jet boxes 21 and 22 is 1/100 or less, and the through holes 21d2 and 22d2 and the ejection holes 21c2 and 22c2 are independent (that is, The average opening area ratio (per piece) is 1/5 or more and 5 or less. In this case, when considering the jet boxes 21 and 22 as a unit, the total opening area of the through holes 21d2 and 22d2 is at most 5/100 (5%) of the total opening area of the ejection holes 21c2 and 22c2. Heat loss (waste heat) in drying can be kept to a minimum.

Here, the shapes of the upper and lower jet boxes 21 and 22 of this embodiment will be specifically described. The shape of the jet boxes 21 and 22 may be different from that of this embodiment.

The lower jet box 22 is positioned below the veneer single plate W, and as shown in FIG. It is formed in a pseudo-rectangular shape). The hot air A1 flowing through the jet box 22 is jetted out of the box (outside of the jet box 22) from jet holes 22c2 formed in the ceiling wall portion 22c to dry the lower surface of the veneer veneer W. As shown in FIG. 13, the reflecting member 22d1 is included in the inner bottom portion 22T in such a manner that it obliquely intersects with the airflow direction in a plan view so as to approach (approach) the one side wall portion 22s toward the downstream side in the airflow direction. It is fixedly arranged at the portion 22t. One end of the reflecting member 22d1 here is in contact with one side wall portion 22s (the right side in FIG. 8). The through-hole 22d2 opens at a position facing the reflecting member 22d1 on one side wall 22s. The hot air A1 flowing through the bottom of the lower jet box 22 is decelerated by the reflecting member 22d1 and is redirected to approach one of the side walls 22s, and flows out of the box (outside of the jet box 22) through the through hole 22d2. .

Here, one or a plurality of through holes 22d2 are formed in the ventilation direction in one side wall 22s. As shown in FIG. 14, the through hole 22d2 is open in a square shape, and the lower edge of the opening is at the same or equivalent position as the top surface of the bottom wall portion 22t. The reflecting member 22d1 is a plate material (reflecting plate) that extends linearly here, and has a height that is the same as or equivalent to the opening height (opening width in the height direction) of the through hole 22d2.

Also, the ejection hole 22c2 of the ceiling wall portion 22c is not formed on one side wall portion 22s side (the right side in FIG. 8), and is biased toward the other side wall portion 22s side (the left side in FIG. 8). The through hole 22d2 here is penetratingly formed in one side wall portion 22s (the right side in FIG. 8) which is the non-forming side of the ejection hole 22c2. Also, the reflecting member 22d1 here is arranged on the bottom wall portion 22t (see FIG. 13) immediately below the non-formation region 22F of the ejection holes 22c2 in the ceiling wall portion 22c.

The upper jet box 21 is located above the veneer single plate W, and as shown in FIG. It is formed in a pseudo-rectangular shape having a portion 21c1. The bottom wall portion 21c of the upper jet box 21 is formed with projecting wall portions 21c1 forming reinforcing ribs having a triangular cross-section along the ventilation direction between the rows of the ejection holes 21c2 and on both outer sides of the rows. The reflecting member 21d1 and the through hole 21d2 are arranged in the projecting wall portion 21c1. Note that there are three types of first to third reflecting members 21d1 in this embodiment.

As shown in FIG. 9, the first reflecting member 21d1 is fixedly arranged between the rows of the ejection holes 21c2 in the bottom wall portion 21c included in the inner bottom portion 21C. The protruding wall portion 21c1 forming the reinforcing rib is formed in a form that expands in a V-shape in the direction of airflow in a plan view so as to approach (approach). The through-hole 21d2 in this case opens at a collective portion 21D sandwiched between the V-shaped reflecting members 21d1 in the bottom wall portion 21c.

Specifically, as shown in FIG. 9A, each projecting wall portion 21c1 between the rows of the ejection holes 21c2 has two plate-like portions 21F, 21F extending in the ventilation direction (direction of arrow A1). ) is connected to form a projecting tip 21e0 (top) having a triangular cross section. The two plate-like portions 21F, 21F forming the protruding tip portion 21e0 (top portion) are connected to each other and form a point 2e0 of the protruding tip portion 21e0 (top portion) to ventilate along the protruding tip portion 21e0 (top portion). A notch 2e2 extending for a predetermined length in a direction (direction of arrow A1), and a point 2e0 extending obliquely for a predetermined length from the point 2e0 toward the ventilation direction (direction of arrow A1) so as to separate from the projecting tip portion 21e0 (top portion). Cuts 2e1, 2e1 are provided (Fig. 9(a) → Fig. 9(b)). Then, as shown in FIG. 9(b), the triangular portions 2e4 and 2e4 sandwiched between the cut 2e2 and the cuts 2e1 and 2e1 are formed by dividing the end point opposite to the point 2e0 of the cut 2e2 and the point 2e0 of the cuts 2e1 and 2e1. 9(b)→FIG. 9(c). As shown in FIG. 9(c), the bent triangular portions 2e4 and 2e4 are arranged such that the end sides 2e5 and 2e5 forming one side close to each other are closely opposed to each other or are connected by welding or the like so as to extend in the airflow direction. It functions as a V-shaped reflecting member 21d1 (reflecting plate) having an opposite side and an inclined surface facing downward. On the other hand, openings are formed in both the plate-like portions 21F, 21F by these bendings, and the openings function as through holes 21d2.

In this manner, the bottom wall portion 21c is sandwiched between the V-shaped reflecting members 21d1 and formed with a diamond-shaped collecting portion 21D (first collecting portion) opening downward. As shown in FIG. 9(c), the two triangular plate-like portions 2e4 and 2e4 forming the reflecting member 21d1 are arranged such that the upstream side of one side of the triangular base end (bent portion) is mutually offset. An inclined arrangement is such that the two sides of the triangular projecting side (end side portions 2e5 and 2e5) that are close to each other (end side portions 2e5 and 2e5) are positioned so as to be closer to each other on the farther downstream side (here, they are in contact with each other). The hot air A1 (A10) heading downstream is directed downward while moving toward the intermediate position of each other as it progresses downstream.

As shown in FIG. 10, the second reflecting member 21d1 is fixed at a position further outside the row of the outermost ejection holes 21c2 located on the one side wall portion 21s side (the right side in FIG. 7) in the bottom wall portion 21c. are placed. The second reflecting member 21d1 has the protruding wall portion 21c1 forming the outermost reinforcing rib located on one side wall portion 21s side (the right side in FIG. 7), which is closer to both side wall portions 21s, 21s toward the upstream side ( It is formed in a form that expands in a substantially V-shape in the direction of airflow in a plan view so as to approach the airflow direction. In this case, the through-hole 21d2 opens at a collective portion 21D sandwiched between the substantially V-shaped reflecting members 21d1, 21d1 at the bottom wall portion 21c.

Specifically, as shown in FIG. 10(a), the outermost projecting wall portion 21c1 located on one side wall portion 21s side (the right side in FIG. 10) has two plate-like portions 21F, 21F extending in the ventilation direction. ' are connected to form a protruding tip 21g0 (top) having a triangular cross section extending in the ventilation direction (direction of arrow A1). Both plate-shaped portions 21F and 21F' forming the protruding tip portion 21g0 (top portion) have a gentler slope than the plate-shaped portion 21F, and the protruding tip portion 21g0 formed by being connected to each other. A notch 2g2 extending a predetermined length in the ventilation direction (direction of arrow A1) along the projecting tip 21g0 (top) from one point 2g0 (top), and from the one point 2g0 toward the ventilation direction (direction of arrow A1) Then, cuts 2g1 and 2g1' are provided so as to obliquely extend a predetermined length away from the projecting tip 21g0 (top) (FIG. 10(a)→FIG. 10(b)). Then, as shown in FIG. 10(b), a triangular portion 2g4 sandwiched between the cut 2g2 and the cut 2g1 is defined as an end point opposite to the point 2g0 of the cut 2g2 and an end point opposite to the point 2g0 of the cut 2g1. , is bent upward along a straight line 2g3 connecting . Similarly, a straight line 2g3' that connects the triangular portion 2g4' sandwiched between the cut 2g2 and the cut 2g1' to the end point opposite to the point 2g0 of the cut 2g2 and the end point opposite to the point 2g0 of the cut 2g1'. is bent upward (FIG. 10(b)→FIG. 10(c)). As shown in FIG. 10(c), the bent triangular portions 2g4 and 2g4' are formed by making the end sides 2g5 and 2g5' forming one side close to each other close to each other or connecting them by welding or the like. It functions as the substantially V-shaped reflecting member 21d1 (reflecting plate) having an inclined surface facing downward and on the side opposite to the ventilation direction. On the other hand, openings are formed in both the plate-like portions 21F and 21F' by bending them, and the openings function as through holes 21d2.

In this manner, the bottom wall portion 21c is sandwiched between the substantially V-shaped reflecting members 21d1 and formed with a collective portion 21D (second collective portion) opening downward in a substantially diamond shape. As shown in FIG. 10(c), the two V-shaped plate-like portions 2g4 and 2g4' forming the reflecting member 21d1 are arranged such that one side of the triangular base end (bent portion) is inclined toward the upstream side. Positioned so that they are separated from each other and closer to each other toward the downstream side, and the two sides of the triangular projecting side that are close to each other (end side portions 2e5 and 2e5′) are brought close to each other (in this case, they are in contact). The hot air A1 (A10) is arranged in a slanted manner so that the downstream hot air A1 (A10) is directed downward while moving toward the intermediate position of each other as it progresses downstream.

As shown in FIG. 11, the third reflecting member 21d1 is fixed at a position further outside the row of the outermost ejection holes 21c2 located on the side of the other side wall portion 21s (left side in FIG. 7) in the bottom wall portion 21c. are placed. The third reflecting member 21d1 moves the protruding wall portion 21c1 forming the outermost reinforcing rib located on the other side wall portion 21s side (the left side in FIG. 7) toward the other side wall portion 21s side toward the upstream side. ), it is formed in a form that expands in a substantially V-shape in the direction of airflow in a plan view. In this case, the through-hole 21d2 opens at a collective portion 21D sandwiched between the reflecting member 21d1 and a portion 2s (see FIG. 11(c)) of the other side wall portion 21s facing the reflecting member 21d1 at the bottom wall portion 21c.

Specifically, the outermost projecting wall portion 21c1 located on the side of the other side wall portion 21s (left side in FIG. 11) is, as shown in FIG. The portion 21s is connected to form a projecting tip portion 21f0 (top portion) having a triangular cross section extending in the ventilation direction (the direction of the arrow A1). The plate-like portion 21F forming the protruding tip portion 21f0 (top portion) has a protruding tip portion 21f0 (top portion) from a point 2f0 of the protruding tip portion 21f0 (top portion) formed by connecting to the lower end of the other side wall portion 21s. A cut 2f2 extending a predetermined length in the ventilation direction (direction of arrow A1) along the , and from the one point 2f0 toward the ventilation direction (direction of arrow A1), diagonally away from the protruding tip 21f0 (top) A notch 2f1 extending for a predetermined length is formed (FIG. 11(a)→FIG. 11(b)). Then, as shown in FIG. 11(b), a triangular portion 2f4 sandwiched between the cut 2f2 and the cut 2f1 is defined as an end point opposite to the point 2f0 of the cut 2f2 and an end point opposite to the point 2f0 of the cut 2f1. , and is bent upward (FIG. 11(b)→FIG. 11(c)). As shown in FIG. 11(c), the bent triangular portion 2f4 is arranged on the side opposite to the airflow direction by making the edge portion 2f5 face the other side wall portion 21s closely or by welding or the like. and functions as the substantially V-shaped reflecting member 21d1 (reflecting plate) having an inclined surface facing downward. On the other hand, an opening is formed in the plate-like portion 21F by this bending, and the opening functions as a through hole 21d2.

In this way, the bottom wall portion 21c is sandwiched between the other side wall portion 21s and the other side wall portion 21s by the substantially V-shaped reflecting member 21d1, and a collective portion 21D (third collective portion) opening downward in a substantially triangular shape is formed. ) is formed. As shown in FIG. 11(c), the plate-like portion 2f4 forming the reflecting member 21d1 has one side, which is the base end side (bent portion) of the triangular shape, away from the side wall portion 21s at the close position toward the upstream side and downstream side. and the side (end side 2f5) of the two sides of the protruding side of the triangular shape, which is closer to the side wall 21s at the close position, is inclined to approach (in this case, contact with) the side wall 21s. is made so that the downstream hot air A1 (A10) is directed downward while being drawn toward the side wall portion 21s at the close position as it advances downstream.

The hot air A1 flowing through the upper jet box 21 is ejected outside the box (outside the jet box 21) from the ejection holes 21c2 formed in the bottom wall portion 21c to dry the upper surface of the veneer veneer W. A part (A10) of the hot air A1 flowing through the bottom of the jet box 21, as shown in FIGS. flow inside the protruding wall portion 21c1 (auxiliary rib) having a triangular cross-section located at , is decelerated by the reflecting member 21d1, changes its direction to the collective portion 21D, and flows out of the box (outside of the jet box 21) through the through hole 21d2. It flows out and reaches the upper surface of the veneer veneer W.

FIG. 12 is a cross section of the protruding wall portion 21c1 (FIG. 9) between the rows of the ejection holes 21c2 cut along the protruding tip portion (top portion). It is a diagram. However, even when the protruding wall portions 21c1 (FIGS. 10 and 11) on both outer sides of the row of the ejection holes 21c2 are cut in the same manner, the same sectional view appears.

As shown in FIG. 1, in the multistage conveying hot air drying apparatus 1 of this embodiment, the conveying path Q of each stage is divided into a plurality of heating sections 2 parallel to the ventilation direction. Each heating section 2 surrounds the conveying path Q of all the stages, and a circulation air path P (see FIG. 2) is formed therein, and a return air A3 directed from the circulation fan 4 to the heater 3 is adjacent in the return area P3. A plurality of vertical frames 33 (see FIG. 1) and horizontal frames 34 (see FIGS. 1, 2, and 7) are formed in a rectangular parallelepiped box shape so as to be able to partially communicate with the returning air A3 of the heating section 2. configured in combination.

In at least one of the plurality of heating sections 2, part of the return air A3 directed from the circulation fan 4 toward the heater 3 is returned to the return area P3 of the circulation air passage P formed inside. A discharge air passage P5 is connected for discharging into the atmosphere. Here, one discharge air passage P5 is connected to a predetermined number (here, five) of heating sections 2 that are connected. In the corresponding heating section 2, the exhaust air A2 from the ventilation area P1 of each stage is sucked and discharged by the circulation fan 4 through the gathering area P2, and partly (a part of the returning air A3 ) is branched and discharged into the atmosphere through the discharge air path P5.

As shown in FIG. 2, the discharge air path P5 rises upward from the return area P3, changes its direction substantially at a right angle, and extends out of the apparatus and further to the outside of the building in which the apparatus is housed. It is formed by an exhaust duct 50 provided. A damper 51 whose opening and closing is controlled by an actuator (not shown) such as a cylinder is installed near the entrance of the exhaust duct 50 . A filter part 52 is installed in the middle part of the duct 50 to remove dust generated from the veneer veneer W during drying.

In this embodiment, as shown in FIG. 2, a maintenance door 9 is provided on the wall surface 2b that defines the gathering area P2 side of each heating section 2 so that workers can enter the gathering area P2. there is By opening the maintenance door 9, the worker can easily take out the dust accumulated on the bottom of the heating section 2 (on the bottom surface 2d).

Although one embodiment of the present invention has been described above, this is merely an example, and the present invention is not limited to this. Various modifications such as additions and omissions are possible based on the above.

For example, in the above embodiment, a plurality of sets of upper and lower roll sets 10 are arranged to sandwich the veneer veneer W (plywood plate material) and convey the roll transfer type, but the present invention is not limited to this. Other transport types such as a wire mesh transport type in which the veneer veneer W is transported while being sandwiched between a pair of upper and lower wire meshes wound in a belt shape may be used.

In the lower jet box 22 of the above embodiment, the through hole 22d2 is formed through the side wall portion 22s (the right side in FIG. 8) on the non-formation side of the ejection hole 22c2, and the reflecting member 22d1 is formed on the non-formation side of the ejection hole 22c2. Although they are arranged on the formation side (immediately below the non-formation region 22F), they may be arranged at other positions. For example, the through hole 22d2 may be provided both on one side wall portion 22s side and on the opposite side wall portion 22s. In this case, the through-holes 22d2 may be provided alternately on both the one side wall portion 22s side and the other side wall portion 22s in the ventilation direction, and the reflecting member 22d1 may be provided so as to correspond to each through-hole 22d2. . This configuration may be applied to the case where the ejection holes 22c2 are not formed unevenly on one of the side wall portions 22s, 22s.

Further, in the upper jet box 21 of the above embodiment, the through holes 21d2 are provided in the protruding wall portions 21c1 having a triangular cross-section between the rows of the ejection holes 21c2 formed in the ventilation direction and on both outer sides of the rows ( See Figure 7). There are a plurality of protruding wall portions 21c1 (two in FIG. 7) located between the rows of the ejection holes 21c2, and there is one protruding wall portion 21c1 located on both outer sides of the rows on each side. A through hole 21d2 is formed at the same position in the ventilation direction in 21c1. In such a plurality of protruding wall portions 21c1, the through-holes 22d2 may be formed at different positions in the ventilation direction.

In the above embodiment, each of the upper and lower jet boxes 21 and 22 has reflecting members 21d1 and 22d1 (for example, reflecting plates) serving as resistance members and through holes 21d2 and 22d2. Only one of the jet boxes 21, 22 may have reflecting members 21d1, 22d1 (for example, reflecting plates) serving as resistance members and through holes 21d2, 22d2.

The reflecting member 22d1 of the lower jet box 22 is fixed to the bottom wall portion 22t so as to be closer to one side wall portion 22s toward the downstream side. The proximity here includes both contact (connection) and non-contact with one side wall portion 22s. In addition, the reflecting member 22d1 is arranged in a form obliquely intersecting with the ventilation direction in a plan view so as to approach one of the side walls toward the downstream side. This includes the case where the reflective member 22d1 is arranged in a form (see FIG. 15) extending long so as to straddle between one side wall portion 22s and the other side wall portion 22s. In this case, the reflecting member 22d1 only needs to be close to one of the side walls 22s. It's okay. Therefore, any combination of contact and non-contact with one side wall portion 22s and the other side wall portion 22s of the reflecting member 22d1 can be selected.

Further, the reflecting member 22d1 of the lower jet box 22 in the above embodiment has an angle θ (see FIGS. 13 and 15) formed by the extension direction G thereof and the ventilation direction (the direction of the arrow A1) of 20° or more and 45°. Hereafter, by more desirably 30° or more and 35° or less, it is possible to more reliably discharge small and light contaminants mixed in the hot air from the through hole 22d2.

Further, the reflecting member 21d1 of the upper jet box 21 in this embodiment is formed by bending a part of the protruding wall portion 21c1 having a triangular cross section as described above, but it may be formed by other methods. . For example, after cutting a part of the protruding wall portion 21c1, it may be formed by joining.

1 multi-stage conveying hot air dryer 2 heating section 3 heater 4 circulation fan 10 feeding roll group 11 upper roll 12 lower roll 20 jet box group (ventilation duct group)
21 upper jet box (upper duct)
21c Bottom wall portion 21s of upper jet box Side wall portion 21t of upper jet box Ceiling wall portion 21D of upper jet box Gathering portion 22 Lower jet box (lower duct)
22c Ceiling wall portion of lower jet box 22s Side wall portion 22t of lower jet box Bottom wall portions 21c1, 22c1 of lower jet box Protruding wall portions (reinforcing ribs)
21c2, 22c2 ejection holes 21d1, 22d1 reflecting member (resistance member/reflecting plate)
21d2, 22d2 Through holes 21C, 22T Inner bottom 31 Vertical beam 32 Horizontal beam 33 Vertical frame 34 Horizontal frame 320 Casing W Veneer single plate (veneer plate material)
Q Conveyance path P Circulation air path P1 Ventilation area P2 Gathering area P3 Return area P4 Distribution area P5 Discharge air path

Claims (8)

Conveyance paths for horizontally conveying multiple rows of veneer sheets in parallel are provided in multiple stages, and a hot air circulation air path is formed in a vertical cross section that intersects the conveyance direction of the veneer sheet material in each stage of the conveyance path, A multi-stage conveying hot air drying apparatus for drying by blowing hot air of the circulation air passage to each stage of plywood board material being conveyed along the conveying direction,
When the vertical cross section is viewed from the front, the circulation air passage circulates the hot air along the ventilation direction parallel to the plywood plate material of each stage and blows out the hot air to the upper and lower surfaces of the plywood plate material respectively. A ventilation area formed for each stage and a downstream side of the ventilation area of each stage in the ventilation direction, which are configured by upper and lower ventilation ducts having ejection holes, are vertically communicated with each other, and the airflow from the ventilation area of each stage is communicated. A collection area in which a single suction fan is arranged in the upper part for sucking the exhaust air, and the returning air from the suction fan crosses the uppermost conveying path in a direction opposite to the ventilation direction, A return area that flows into a heater arranged opposite to the suction fan, and a distribution area that flows the hot air heated by the heater downward and distributes it to the upstream side of the ventilation areas of each stage in the ventilation direction. , including
At least one of the upper and lower ventilation ducts has a resistance member disposed on the inner bottom to change the direction of the flow while applying resistance to a part of the flow of hot air flowing in the ventilation direction to decelerate it; a through hole formed in one of the wall surfaces for guiding out of the duct the hot air whose direction is changed while being decelerated by the member;
In the ventilation area of each stage, the hot air flowing inside the upper and lower ventilation ducts in the ventilation direction is ejected out of the ducts from the ejection holes to vertically move the plywood board conveyed in the conveying direction along the corresponding conveying path. A multi-stage conveying hot air drying apparatus characterized in that drying is performed from both sides, and part of the flow whose direction is changed while being decelerated by the resistance member inside flows out of the duct through the through hole. A transport path in which multiple sets of feeding rolls consisting of long upper rolls and lower rolls are arranged at predetermined intervals, and multiple rows of veneer sheets are horizontally transported in parallel while being sequentially sandwiched between the upper and lower rolls of each set. are provided in upper and lower multiple stages, and hot air circulation paths are formed in the vertical cross section perpendicular to the conveying direction of the plywood material in each stage of the conveying path, and the plywood material on each stage being conveyed along the conveying direction On the other hand, a multistage conveying hot air drying device for drying by blowing hot air in the circulation air passage,
When the vertical cross section is viewed from the front, the circulation air passage circulates the hot air along the ventilation direction parallel to the plywood plate material of each stage and blows out the hot air to the upper and lower surfaces of the plywood plate material respectively. A ventilation area formed for each stage and a downstream side of the ventilation area of each stage in the ventilation direction, which are configured by upper and lower ventilation ducts having ejection holes, are vertically communicated with each other, and the airflow from the ventilation area of each stage is communicated. A collection area in which a single suction fan is arranged in the upper part for sucking the exhaust air, and the returning air from the suction fan crosses the uppermost conveying path in a direction opposite to the ventilation direction, A return area that flows into a heater arranged opposite to the suction fan, and a distribution area that flows the hot air heated by the heater downward and distributes it to the upstream side of the ventilation areas of each stage in the ventilation direction. , including
At least one of the upper and lower ventilation ducts has a resistance member disposed on the inner bottom to change the direction of the flow while applying resistance to a part of the flow of hot air flowing in the ventilation direction to decelerate it; a through hole formed in one of the wall surfaces for guiding out of the duct the hot air whose direction is changed while being decelerated by the member;
In the ventilation area of each stage, the hot air flowing inside the upper and lower ventilation ducts in the ventilation direction is ejected out of the ducts from the ejection holes to vertically move the plywood board conveyed in the conveying direction along the corresponding conveying path. A multi-stage conveying hot air drying apparatus characterized in that drying is performed from both sides, and part of the flow whose direction is changed while being decelerated by the resistance member inside flows out of the duct through the through hole. 3. The multi-stage conveying hot air according to claim 1, wherein the hot air flowing in the airflow direction is reflected by the resistance member to change its traveling direction, and the through hole is positioned in the direction in which the hot air is reflected when viewed from the resistance member. drying equipment. 4. The multi-stage conveying hot air drying apparatus according to claim 1, wherein the through holes in each of the ventilation ducts are formed in a shape different from that of the ejection holes. Each of the ventilation ducts is provided with a plurality of through holes and a plurality of ejection holes,
The number ratio of the through-holes and the ejection holes is 1/100 or less in the unit of the ventilation duct, and the average opening area ratio of the through-holes and the ejection holes is 1/5 or more and 5 or less. 5. The multistage conveying hot air drying apparatus according to any one of claims 1 to 4. Of the upper and lower ventilation ducts, the lower ventilation duct located below the veneer plate is formed in a rectangular or pseudo-rectangular cross section orthogonal to the ventilation direction,
The hot air flowing through the lower ventilation duct blows out of the duct from the ejection holes formed in the ceiling wall to dry the lower surface of the plywood board,
The resistance member is fixed to the bottom wall portion in such a manner that it obliquely intersects with the airflow direction in a plan view so as to approach one side wall portion toward the downstream side, and the through hole is formed in the one side wall portion. and open in a position facing the
The hot air flowing through the bottom portion of the lower ventilation duct is decelerated by the resistance member and is redirected to approach the one side wall portion, and flows out of the duct through the through hole. The multi-stage conveying hot air drying apparatus according to any one of items 1 to 3. Of the upper and lower ventilation ducts, the upper ventilation duct located above the veneer plate is formed in a pseudo-rectangular cross section perpendicular to the ventilation direction,
On the bottom wall of the upper ventilation duct, reinforcing ribs are formed along the ventilation direction between the rows of the ejection holes arranged in a plurality of rows along the ventilation direction and on both outer sides of the rows,
6. The multi-stage conveying hot-air dryer according to claim 1, wherein the resistance member and the through hole are arranged in the reinforcing rib. The hot air flowing through the upper ventilation duct blows out of the duct from the blowout holes formed in the bottom wall to dry the upper surface of the plywood board,
The resistance member is fixed between the rows of the ejection holes in the bottom wall portion in such a manner that the reinforcing ribs are widened in a V-shape in the direction of airflow in a plan view so as to approach both side wall portions toward the upstream side. and the through-hole opens at a collective portion sandwiched between the V-shaped resistance members in the bottom wall portion,
The hot air flowing through the bottom of the upper ventilation duct flows inside the reinforcing ribs located between the rows of the ejection holes, is decelerated by the resistance member, is changed in direction to the collecting portion, and is discharged from the through hole to the outside of the duct. 8. The multistage conveying hot air drying apparatus according to claim 7, wherein the outflow reaches the upper surface of the veneer board material.

Images