A control system and drying method for a single board drying conveyor belt

Abstract

The invention discloses a control system and a drying method for a veneer drying conveyor belt, which belongs to the technical field of veneer drying and is used to solve the problem that intelligent layered loading of veneers cannot be realized, and the drying temperature and drying speed of veneers cannot be regulated according to the drying degree of veneers; the control system comprises a loading module, a drying module, and a discharging detection module; at the board placing end of the dryer, the board is automatically adsorbed and the veneer drying demand coefficient is obtained by processing initial data when the board is adsorbed, and the board is automatically placed in layers according to the veneer drying demand coefficient. The drying temperature and conveying speed of the dryer can be automatically and intelligently regulated according to the drying demand of the wood veneers, thereby greatly improving the drying quality of the wood boards. At the same time, after the drying of the wood veneers is completed, a feedback signal can be generated for the drying quality of this batch of wood veneers and sent to the drying module, so that the data of the drying module is updated, so that the final drying quality of the wood veneers is better.

Description

Technical Field

[0001] The invention belongs to the technical field of veneer drying, and in particular relates to a control system and a drying method for a veneer drying conveyor belt. Background Art

[0002] The veneer drying and conveying system is a kind of equipment used in the wood processing industry. It is mainly used to convey and dry wood boards with high humidity to achieve the required humidity level. The system is usually composed of multiple components, including a drying chamber, a conveyor belt, a heating device, a fan, a control system, etc. In the veneer drying, the wood boards with high humidity are placed in the drying chamber, and the heating device generates heat energy and circulates the hot air into the drying chamber through the fan. The hot air contacts the wood boards and absorbs moisture in the wood. It is then discharged from the drying chamber and heated again to form a cycle. Through the process of cyclic heating and dehumidification, the moisture in the wood boards is gradually evaporated to reach the required humidity level.

[0003] The existing veneer drying equipment cannot realize intelligent layered loading of veneers when drying veneers, and during the process of drying veneers, the drying temperature and drying speed of the veneers cannot be adjusted according to the drying degree of the veneers. For this reason, we propose a control system and drying method for a veneer drying conveyor belt. Summary of the invention

[0004] The object of the present invention is to provide a control system and a drying method for a single board drying conveyor belt, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a control system and drying method for a veneer drying conveyor belt, comprising a loading module, a drying module, and a discharging detection module, characterized in that: the loading module controls the loading device and loads the wood veneers in layers according to the veneer drying demand coefficient, the drying module dries the wood veneers by adjusting the temperature, conveying speed and heat dissipation fan of the dryer, and the discharging detection module detects the dried and discharged veneers and controls the cooling fan to cool the veneers.

[0006] Preferably, the loading module controls the wood veneer on the material preparation and conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device;

[0007] When the wood veneer is adsorbed and loaded, the initial data of the wood veneer is collected, and the initial data is processed to obtain the veneer drying demand coefficient. The initial data includes: size influence coefficient, veneer initial temperature, veneer initial moisture content. The specific process is:

[0008] Obtain the length, width and thickness of the single board, and perform a comprehensive analysis of the length, width and thickness of the single board to obtain the size influence coefficient WF;

[0009] By randomly setting multiple detection points on the wood veneer, collecting the surface temperature and moisture content of the veneer at each detection point, summing up the surface temperature and moisture content of the veneer at all detection points and taking the average as the initial temperature C and initial moisture content H of the veneer, and at the same time extracting the highest drying temperature Cm of the dryer, the maximum moisture content Hm of this type of veneer in history, and the maximum size influence coefficient WFm of this type of veneer in history from the dryer drying wood database, according to the formula: The single board drying demand coefficient DRI is calculated, where d1, d2, and d3 are preset weight coefficients.

[0010] Preferably, the specific process of drying the single board in layers according to the single board drying requirement coefficient is:

[0011] By matching the veneer drying demand coefficient with the preset veneer drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer and the top drying layer, after successful matching, the veneer on the vacuum suction cup adsorption device is transported to the corresponding drying layer of the dryer through the swing table dividing device for transportation and drying.

[0012] Preferably, the specific process of the drying module regulating the temperature and conveying speed of the drying machine is:

[0013] Each of the three drying layers in the dryer is equipped with a separate conveying device. When each conveying device conveys the first batch of single boards, the average of the DRI interval values ​​corresponding to the drying layer is extracted as the temperature speed value. According to the historical data of the dryer's effective drying of single boards, a mapping relationship between the DRI value and the drying temperature and conveying speed is established. According to the temperature speed value, the appropriate drying temperature and conveying speed are determined from the mapping relationship. After the first batch of single boards are dried on the drying layer, the average of the DRI values ​​of this batch of single boards is extracted as the temperature speed value to re-regulate the drying temperature and conveying speed.

[0014] Preferably, the specific process of regulating the heat dissipation fan to dry the wood veneer is:

[0015] During the drying process, the numerical change of DRI is monitored in real time, and a rectangular coordinate system is established with the distance from the feed port to the discharge port as the horizontal axis and the single board drying demand coefficient as the vertical axis. A DRI change curve is drawn in the rectangular coordinate system, and a preset DRI curve is drawn at the same time. The DRI change curve and the preset DRI curve are calculated. When the DRI change curve and the preset DRI curve are from the feed port to the first group of cooling fans, the area above the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-exceeding area, and the area below the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-reducing area. The pre-exceeding area and the pre-reducing area are counted respectively, and the difference between the two is made, and the difference is marked as the adjustment threshold;

[0016] The corresponding relationship between the adjustment threshold and the change rate of the cooling fan wind speed is set, that is, each unit of positive adjustment threshold corresponds to a decrease of X% in the current cooling fan wind speed, and each unit of negative adjustment threshold corresponds to an increase of Y% in the current cooling fan wind speed, wherein X and Y are both constants, and the wind speed of the first group of cooling fans is adjusted by matching the adjustment threshold with the change rate of the cooling fan wind speed;

[0017] The wind speed control method of the second group of cooling fans and the third group of cooling fans is the same as that of the first group of fans, wherein the segment of the DRI variation curve selected for the wind speed control of the second group of cooling fans and the preset DRI curve is the distance between the first group of cooling fans and the second group of cooling fans;

[0018] The segment of the DRI change curve selected for the wind speed control of the third group of cooling fans and the preset DRI curve is the distance between the second group of cooling fans and the third group of cooling fans when adjusting the fans.

[0019] Preferably, the process of the discharge detection module detecting the single board discharged from the drying is:

[0020] The veneers after drying are tested to obtain the veneer size stability value, the color distribution uniformity value when the veneers are out of the board, and the veneer drying requirement coefficient when the veneers are out of the board. The three are comprehensively analyzed to obtain the veneer quality evaluation coefficient. The quality evaluation coefficient of the veneer is compared with the preset qualified quality evaluation coefficient range. If it is within the range, it indicates that the veneer drying quality is qualified. If it is not within the range, it indicates that the veneer drying quality is unqualified.

[0021] Preferably, the specific process of obtaining the dimensional stability value of the single board is:

[0022] The veneer is evenly divided into several test areas according to its size, and the center line of the test area is used as the warping reference line. For each test area, the maximum vertical distance between the warping reference line and the actual wood surface is measured and marked as the warping value H of the test area;

[0023] The diagonal line of the detection area is used as the distortion reference line, and the difference between the actual distance and the straight-line distance between the distortion reference lines of each detection area is measured and marked as the distortion value T of the detection area;

[0024] By substituting the warpage value H of the inspection area and the distortion value T of the inspection area into the preset formula: The single board dimensional stability value S is obtained, where wh is the weight coefficient of warpage, wt is the weight coefficient of twisting, i is the number of the inspection area, i=1, 2, 3, ..., n, and n is the total number of inspection areas.

[0025] Preferably, the process of obtaining the color distribution uniformity value when the single board is output is:

[0026] Use a high-definition camera to shoot each inspection area to obtain a single-board image of the inspection area, evenly distribute a number of sampling points on the single-board image of each inspection area, convert the single-board image of each inspection area from the original RGB color space to the LAB color space, and record the L, A, and B channel values ​​of each sampling point in the LAB color space;

[0027] Get the L, A, and B channel values ​​of each sampling point in the detection area, and calculate the L, A, and B channel values ​​of each sampling point in the detection area to obtain the standard deviation of the L channel value LX, the standard deviation of the A channel value AX, and the standard deviation of the B channel value BX in the detection area. Use the formula The color distribution uniformity value CUV of the single board when it is output is obtained, where b1, b2, and b3 are the preset weight factors of the L, A, and B channels respectively.

[0028] Preferably, the process of determining whether the veneer drying quality is qualified or unqualified is as follows:

[0029] If unqualified: firstly, take out the single board that is not in the qualified interval value, and then perform a secondary drying operation, and then make the quality evaluation coefficient of the single board subtract from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the single board drying quality deviation value; by matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is output after the match is successful, where T is a constant, and the wind speed adjustment value T is fed back to the drying module, and the drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T;

[0030] If qualified: a drying good signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the single board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the single board according to the quality evaluation coefficient of the single board;

[0031] The mapping relationship between the quality assessment coefficient and the cooling fan speed and the conveying speed in the cooling area is set, and then the cooling fan speed and the conveying speed in the cooling area are regulated according to the quality assessment coefficient. When the qualified single board is conveyed out of the cooling area, it will be conveyed to the horizontal conveying device through the board discharge roller device, and then pass through the sorting belt and the board collecting machine to enter the interior of the palletizer. After the palletizer sorts the single boards, the single boards can be discharged from the board discharge port.

[0032] Preferably, a veneer drying method comprises the following steps:

[0033] Step 1: The loading module controls the wood veneer on the material preparation conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device, and collects the initial data of the wood veneer when adsorbing and loading the wood veneer;

[0034] Step 2: Process the initial data to obtain the veneer drying demand coefficient, and match the veneer drying demand coefficient with the preset veneer drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer, and the top drying layer. After the match is successful, the veneer on the vacuum suction cup adsorption device is transported to the corresponding drying layer of the dryer through the swing table distribution device for transportation and drying;

[0035] Step 3: Extract the mean of the DRI interval values ​​corresponding to the drying layer as the temperature speed value. According to the historical data of the effective drying of the single board by the dryer, establish the mapping relationship between the DRI value and the drying temperature and the conveying speed. According to the temperature speed value, determine the appropriate drying temperature and conveying speed from the mapping relationship. After the first batch of single boards are dried on the drying layer, extract the mean of the DRI values ​​of this batch of single boards as the temperature speed value to re-regulate the drying temperature and conveying speed.

[0036] Step 4: Count the pre-exceeding area and the pre-reducing area, and make a difference between the two. The difference is marked as the adjustment threshold. The corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan is set. By matching the adjustment threshold with the wind speed change rate of the cooling fan, the wind speed of the first group of cooling fans is adjusted. The wind speed control method of the second group of cooling fans and the third group of cooling fans is the same as that of the first group of fans.

[0037] Step 5: Comprehensively analyze the dimensional stability of the veneer after drying, the color distribution uniformity of the veneer when the veneer is out, and the veneer drying requirement coefficient when the veneer is out to obtain the veneer quality evaluation coefficient, and judge whether the veneer drying quality is qualified according to the veneer quality evaluation coefficient;

[0038] If it is not in the qualified interval value: first, the single board that is not in the qualified interval value is taken out, and then a secondary drying operation is performed. Secondly, the quality evaluation coefficient of the single board is subtracted from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the single board drying quality deviation value. By matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is output after the match is successful, and the wind speed adjustment value T is fed back to the drying module. The drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T;

[0039] If the value is in the qualified interval: a good drying signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the single board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the single board according to the quality evaluation coefficient of the single board to prevent the single board from getting damp.

[0040] When qualified veneers are conveyed out of the cooling area, they will be conveyed to the transverse conveying device through the board discharge roller device, and then pass through the sorting belt and the board collector to enter the interior of the palletizer. After the palletizer sorts the veneers, the veneers can be discharged from the board discharge port.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) A control system and drying method for a veneer drying conveyor belt. At the board placement end of the dryer, an automatic board lifting device is used, the upper board is automatically adsorbed, and the veneer drying demand coefficient is obtained by processing the initial data when the upper board is adsorbed. The upper board is automatically placed in layers according to the veneer drying demand coefficient, so as to achieve unmanned fully automatic board loading and drying, which can improve the efficiency of wood veneer loading and can also perform intelligent stratification.

[0043] (2) A control system and drying method for a veneer drying conveyor belt. When the wood veneers are dried in the dryer, the drying temperature and conveying speed of the dryer can be automatically and intelligently adjusted according to the drying requirements of the wood veneers, which greatly improves the drying quality of the wood boards. At the same time, after the drying of the wood veneers is completed, a feedback signal can be generated for the drying quality of this batch of wood veneers and sent to the drying module, and the data of the drying module can be updated, so that the drying module can be more accurate when drying the veneers, and the final drying quality of the wood veneers is better.

[0044] (3) A control system and drying method for a veneer drying conveyor belt. After drying, the wood veneers can be cooled intelligently by the cooling fan in the cooling area. That is, the wind speed and conveying speed of the cooling fan in the cooling area are regulated by the quality evaluation coefficient of the veneer. While cooling the veneer to prevent moisture, the cooling efficiency can be improved. At the same time, the present invention is also provided with a board discharge roller device, a horizontal conveying device, a sorting belt, a board collecting machine and a stacking machine, which can sort the veneers and then discharge them, making it convenient for the staff to sort the veneers. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the overall block diagram of the system of the present invention;

[0046] Figure 2 It is a front view structural schematic diagram of the device of the present invention;

[0047] Figure 3 It is a schematic diagram of the top view of the structure of the device of the present invention;

[0048] Figure 4 It is a structural schematic diagram of the material preparation and conveying device of the equipment of the present invention;

[0049] Figure 5 It is a structural schematic diagram of the swing table material distribution device of the equipment of the present invention;

[0050] Figure 6 It is a structural schematic diagram of a discharging roller device of the equipment of the present invention;

[0051] Figure 7 It is a schematic structural diagram of the transverse conveying device of the equipment of the present invention;

[0052] Figure 8 It is a line graph showing the variation of the drying demand coefficient of the wood veneer in the drying machine of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Embodiment 1

[0055] See also Figure 1-Figure 8The present invention provides a control system and a drying method for a veneer drying conveyor belt, comprising a loading module, a drying module, and a discharging detection module; the loading module controls a loading device to load wood veneers in layers, the drying module dries the wood veneers by adjusting the temperature, conveying speed, and heat dissipation fan of the dryer, and the discharging detection module detects the dried and discharged veneers and controls the cooling fan to cool the veneers to prevent the veneers from getting damp.

[0056] The loading module controls the wood veneer on the material preparation and conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device;

[0057] When the wood veneer is adsorbed and loaded, the initial data of the wood veneer is collected, and the initial data is processed to obtain the veneer drying demand coefficient. The veneer is layered and dried according to the veneer drying demand coefficient. The initial data includes: size influence coefficient, veneer initial temperature, veneer initial moisture content. The specific process is:

[0058] Get the length L, width W, and thickness T of the single board, and get the size influence coefficient according to the formula: WF = L × a1 + W × a2 + T × a3, where a1, a2, and a3 are preset weight factors, and the weight ratio can be allocated according to the sensitivity of the dryer to length, width, and thickness;

[0059] By randomly setting multiple detection points on the wood veneer, collecting the surface temperature and moisture content of the veneer at each detection point, summing up the surface temperature and moisture content of the veneer at all detection points and taking the average as the initial temperature C and initial moisture content H of the veneer, and at the same time extracting the highest drying temperature Cm of the dryer, the maximum moisture content Hm of this type of veneer in history, and the maximum size influence coefficient WFm of this type of veneer in history from the dryer drying wood database, according to the formula: Calculate the single board drying demand coefficient DRI, where d1, d2, and d3 are preset weight coefficients, and the higher the single board drying demand coefficient DRI, the higher the temperature required for drying;

[0060] There are three drying layers inside the veneer dryer and corresponding conveyor belts. The temperature of the bottom drying layer is the highest, followed by the middle drying layer and the top drying layer. The bottom drying layer, the middle drying layer and the top drying layer are all matched with preset veneer drying demand coefficient intervals. The veneer drying demand coefficient DRI is matched with the preset veneer drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer and the top drying layer. After successful matching, the veneer on the vacuum suction cup adsorption device is transported to the corresponding drying layer of the dryer through the swing table dividing device for transportation and drying.

[0061] Embodiment 2

[0062] There are three sets of cooling fans inside the dryer, and the drying module adjusts the cooling fans according to the single board drying demand coefficient;

[0063] Each of the three drying layers in the dryer is equipped with a separate conveying device. When each conveying device conveys the first batch of veneers, the average of the DRI interval values ​​corresponding to the drying layer is extracted as the temperature rate value;

[0064] Based on the historical data of the dryer's effective drying of single boards, a mapping relationship between the DRI value and the drying temperature and conveying speed is established, and the appropriate drying temperature and conveying speed are determined from the mapping relationship based on the temperature and speed values;

[0065] After the drying of the first batch of veneers on the drying layer is completed, the average DRI value of this batch of veneers is extracted as the temperature speed value to re-regulate the drying temperature and conveying speed;

[0066] During the drying process, the DRI value change is monitored in real time. A rectangular coordinate system is established with the distance from the feed port to the discharge port as the horizontal axis and the single board drying demand coefficient as the vertical axis. A DRI change curve is drawn in the rectangular coordinate system, and a preset DRI curve is drawn at the same time, such as Figure 8 As shown, when calculating the DRI change curve and the preset DRI curve from the feed inlet to the first group of heat dissipation fans, the area enclosed by the preset DRI curve and the DRI change curve above the preset DRI curve is marked as the pre-exceeding area, and the area enclosed by the preset DRI curve and the DRI change curve below the preset DRI curve is marked as the pre-reducing area. The pre-exceeding area and the pre-reducing area are counted respectively, and the difference is made between the two, and the difference is marked as the adjustment threshold. If the adjustment threshold is a positive value, it means that the heat supply is slightly more, and the first group of heat dissipation fans will reduce the wind speed. If the adjustment threshold is a negative value, the first group of heat dissipation fans will increase the wind speed. If the wind speed of the first group of heat dissipation fans is reduced, the temperature of the single board surface will increase, and the rate of DRI reduction will increase. On the contrary, if the wind speed of the first group of heat dissipation fans is increased, the surface temperature of the single board will decrease, and the rate of DRI reduction will slow down.

[0067] The corresponding relationship between the adjustment threshold and the change rate of the cooling fan wind speed is set, that is, each unit of positive adjustment threshold corresponds to a decrease of X% in the current cooling fan wind speed, and each unit of negative adjustment threshold corresponds to an increase of Y% in the current cooling fan wind speed, wherein X and Y are both constants, and the wind speed of the first group of cooling fans is adjusted by matching the adjustment threshold with the change rate of the cooling fan wind speed;

[0068] The wind speed control method of the second group of cooling fans and the third group of cooling fans is the same as that of the first group of fans, wherein the segment of the DRI variation curve selected for the wind speed control of the second group of cooling fans and the preset DRI curve is the distance between the first group of cooling fans and the second group of cooling fans;

[0069] The segment of the DRI variation curve selected for the wind speed control of the third group of cooling fans and the preset DRI curve is the distance between the second group of cooling fans and the third group of cooling fans, when adjusting the fans;

[0070] If the temperature of the single board surface needs to be lowered, the heat dissipation fan can collect the hot air blown out when dissipating the heat to lower the temperature inside the dryer, which can be used for subsequent preheating of the single board, thereby improving energy utilization.

[0071] The discharge inspection module comprehensively analyzes the dimensional stability of the veneer after drying, the color distribution uniformity of the veneer when the veneer is discharged, and the veneer drying demand coefficient when the veneer is discharged to obtain the quality evaluation coefficient of the veneer, and judges whether the veneer drying quality is qualified according to the quality evaluation coefficient of the veneer, adjusts the cooling fan according to the judgment result, and feeds back the inspection data to the drying module. The specific process is as follows:

[0072] Detect the warpage of the veneer: divide the veneer evenly into several detection areas according to its size, use the center line of the detection area as the warpage reference line, and measure the maximum vertical distance between the warpage reference line and the actual wood surface for each detection area, and mark it as the warpage value H of the detection area;

[0073] Detect the distortion of the single board: take the diagonal line of the detection area as the distortion reference line, measure the difference between the actual distance and the straight-line distance between the distortion reference lines of each detection area, and mark it as the distortion value T of the detection area;

[0074] By substituting the warpage value H of the inspection area and the distortion value T of the inspection area into the preset formula: The dimensional stability value S of the single board is obtained. The smaller the dimensional stability value S of the single board is, the lower the warping and distortion of the single board is, that is, the better the dimensional stability of the single board is, where wh is the weight coefficient of the warping, wt is the weight coefficient of the distortion, i is the number of the detection area, i=1, 2, 3, ..., n, and n is the total number of the detection areas;

[0075] Use a high-definition camera to shoot each detection area to obtain a single-board image of the detection area. Evenly distribute a number of sampling points on the single-board image of each detection area, and convert the single-board image of each detection area from the original RGB color space to the LAB color space. In the LAB color space, record the L (brightness), A (green-red), and B (blue-yellow) channel values ​​of each sampling point;

[0076] Get the L, A, and B channel values ​​of each sampling point in the detection area, and calculate the L, A, and B channel values ​​of each sampling point in the detection area to obtain the standard deviation of the L channel value LX, the standard deviation of the A channel value AX, and the standard deviation of the B channel value BX in the detection area. Use the formula Get the color distribution uniformity value CUV when the single board is output. The smaller the CUV value, the more uniform the color distribution. b1, b2, and b3 are the preset weight factors of the L, A, and B channels respectively.

[0077] When the veneer is dried in the dryer:

[0078] Get the veneer drying requirement coefficient DRI when the veneer is out of the board, and substitute the veneer drying requirement coefficient DRI when the veneer is out of the board, the veneer dimensional stability value S, and the color distribution uniformity value CUV when the veneer is out of the board into the preset formula Q=DRI×c1+S×c2+CUV×c3 to obtain the quality evaluation coefficient Q of the veneer. The larger the quality evaluation coefficient Q of the veneer, the worse the veneer drying quality, where c1, c2, and c3 are preset weight coefficients.

[0079] By comparing the quality evaluation coefficient Q of the single board with the preset qualified quality evaluation coefficient range, if it is not in the qualified range value: it means that the quality evaluation coefficient Q of the single board is too large, indicating that the single board is unevenly dried, has poor dimensional stability or uneven color distribution when it is dried in the dryer. First, take out the single board that is not in the qualified range value, and then perform a secondary drying operation;

[0080] Secondly, the quality evaluation coefficient Q of the single board is subtracted from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the single board drying quality deviation value, and multiple groups of adjustment intervals are preset, each group of preset adjustment intervals has a single board drying quality deviation value interval, and each group of preset adjustment intervals corresponds to a wind speed adjustment value T, where T is a constant;

[0081] By matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is outputted after the match is successfully made, and the wind speed adjustment value T is fed back to the drying module. The drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T;

[0082] That is, the modification is performed on the basis that each unit positive adjustment threshold corresponds to a decrease in the current cooling fan wind speed by X%, and each unit negative adjustment threshold corresponds to an increase in the current cooling fan wind speed by Y%. That is, each unit positive adjustment threshold corresponds to a decrease in the current cooling fan wind speed by (X+T)%, and each unit negative adjustment threshold corresponds to an increase in the current cooling fan wind speed by (YT)%. That is, the overall cooling fan wind speed is reduced to slow down the heat dissipation and allow the heat to penetrate into the board more evenly.

[0083] After the readjustment is completed, the dryer will continue to monitor the changes in DRI and the drying quality of the veneers in real time when drying the next batch of veneers. Based on the monitoring results, the fan speed will be further fine-tuned until the ideal drying effect is achieved.

[0084] If the value is in the qualified interval, it means that the board drying quality meets the preset requirements, and a good drying signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the board according to the quality evaluation coefficient Q of the board to prevent the board from getting damp.

[0085] The mapping relationship between the quality evaluation coefficient and the cooling fan speed and the conveying speed in the cooling area is set, and the cooling fan speed and the conveying speed in the cooling area are regulated according to the quality evaluation coefficient Q. The larger the quality evaluation coefficient Q, the smaller the cooling fan speed and the slower the conveying speed. The reduction of the conveying speed and the cooling fan speed can slow down the drying speed, so that the heat can penetrate into the single board more evenly, thereby improving the drying quality and color distribution, and then realizing the intelligent control of the cooling fan speed and the conveying speed in the cooling area according to the quality evaluation coefficient Q;

[0086] When qualified veneers are conveyed out of the cooling area, they will be conveyed to the transverse conveying device through the board discharge roller device, and then pass through the sorting belt and the board collector to enter the interior of the palletizer. After the palletizer sorts the veneers, the veneers can be discharged from the board discharge port.

[0087] The working principle and use process of the present invention are as follows: when the device is used, the loading module controls the wood veneer on the material preparation and conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device. When the wood veneer is adsorbed and loaded, the initial data of the wood veneer is collected, and the initial data is processed to obtain the veneer drying demand coefficient. The veneer drying demand coefficient is matched with the preset veneer drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer, and the top drying layer. After the matching is successful, the veneer on the vacuum suction cup adsorption device is conveyed to the corresponding drying layer of the dryer through the swing table dividing device for conveying and drying.

[0088] Each of the three drying layers in the dryer is equipped with a separate conveying device. When each conveying device conveys the first batch of veneers, the average value of the DRI interval value corresponding to the drying layer is extracted as the temperature speed value. According to the historical data of the dryer's effective drying of veneers, a mapping relationship between the DRI value and the drying temperature and conveying speed is established. According to the temperature speed value, the appropriate drying temperature and conveying speed are determined from the mapping relationship. After the drying of the first batch of veneers on the drying layer is completed, the average value of the DRI value of this batch of veneers is extracted as the temperature speed value to re-regulate the drying temperature and conveying speed;

[0089] During the drying process, when calculating the DRI value change curve and the preset DRI curve from the feed port to the first group of cooling fans, the area above the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-exceeding area, and the area below the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-reducing area. The pre-exceeding area and the pre-reducing area are counted respectively, and the difference is made between the two, and the difference is marked as the adjustment threshold. The corresponding relationship between the adjustment threshold and the cooling fan wind speed change rate is set, that is, each unit positive adjustment threshold corresponds to a current cooling fan wind speed reduction of X%, and each unit negative adjustment threshold corresponds to a current cooling fan wind speed increase of Y%. By matching the adjustment threshold with the cooling fan wind speed change rate, the wind speed of the first group of cooling fans is adjusted, and the wind speed control method of the second and third groups of cooling fans is the same as that of the first group of fans;

[0090] The outgoing material detection module comprehensively analyzes the dimensional stability of the veneer after drying, the color distribution uniformity of the veneer when the veneer is out, and the veneer drying demand coefficient when the veneer is out to obtain the quality evaluation coefficient of the veneer, and judges whether the veneer drying quality is qualified according to the quality evaluation coefficient of the veneer;

[0091] If it is not in the qualified interval value: first, take out the veneer that is not in the qualified interval value, and then perform a secondary drying operation, and then make the quality evaluation coefficient of the veneer subtract from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the veneer drying quality deviation value;

[0092] By matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is outputted after the match is successfully made, and the wind speed adjustment value T is fed back to the drying module. The drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T;

[0093] After the readjustment is completed, the dryer will continue to monitor the changes in DRI and the drying quality of the veneers in real time when drying the next batch of veneers. Based on the monitoring results, the fan speed will be further fine-tuned until the ideal drying effect is achieved.

[0094] If the value is in the qualified interval: a good drying signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the single board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the single board according to the quality evaluation coefficient of the single board to prevent the single board from getting damp.

[0095] When qualified veneers are conveyed out of the cooling area, they will be conveyed to the transverse conveying device through the board discharge roller device, and then pass through the sorting belt and the board collector to enter the interior of the palletizer. After the palletizer sorts the veneers, the veneers can be discharged from the board discharge port.

[0096] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control system for a single board drying conveyor belt, comprising a feeding module, a drying module, and a discharging detection module, characterized in that: The feeding module controls the feeding device and loads the wood veneers in layers according to the veneer drying demand coefficient. The drying module dries the wood veneers by adjusting the temperature, conveying speed and cooling fan of the dryer. The discharge detection module detects the veneers discharged from the drying and controls the cooling fan to cool the veneers. The loading module controls the wood veneer on the material preparation and conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device; When the wood veneer is adsorbed and loaded, the initial data of the wood veneer is collected, and the initial data is processed to obtain the veneer drying demand coefficient. The initial data includes: size influence coefficient, veneer initial temperature, veneer initial moisture content. The specific process is: The length, width and thickness of the veneer are obtained, and the length, width and thickness of the veneer are comprehensively analyzed to obtain the size influence coefficient WF. Multiple detection points are randomly set on the wood veneer, and the surface temperature and moisture content of the veneer at each detection point are collected. The surface temperature and moisture content of the veneer at all detection points are summed up and the average is taken as the initial temperature C and initial moisture content H of the veneer. At the same time, the highest drying temperature Cm of the dryer, the maximum moisture content Hm of this type of veneer in history, and the maximum size influence coefficient WFm of this type of veneer in history are extracted from the dryer drying wood database. According to the formula: , calculate the single board drying demand coefficient DRI, where d1, d2, and d3 are preset weight coefficients; The specific process of layered drying of veneers according to the veneer drying demand coefficient is as follows: By matching the single board drying demand coefficient with the preset single board drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer and the top drying layer, after successful matching, the single board on the vacuum suction cup adsorption device is transported to the corresponding drying layer of the dryer through the swing table distribution device for transportation and drying; The specific process of the drying module controlling the temperature and conveying speed of the dryer is as follows: Each of the three drying layers in the dryer is equipped with a separate conveying device. When each conveying device conveys the first batch of single boards, the average of the DRI interval values ​​corresponding to the drying layer is extracted as the temperature speed value. According to the historical data of the dryer's effective drying of single boards, a mapping relationship between the DRI value and the drying temperature and conveying speed is established. According to the temperature speed value, the appropriate drying temperature and conveying speed are determined from the mapping relationship. After the first batch of single boards are dried on the drying layer, the average of the DRI values ​​of this batch of single boards is extracted as the temperature speed value to re-regulate the drying temperature and conveying speed.

2. A control system for a veneer drying conveyor belt according to claim 1, characterized in that: The specific process of regulating the heat dissipation fan to dry the wood veneer is: During the drying process, the numerical change of DRI is monitored in real time, and a rectangular coordinate system is established with the distance from the feed port to the discharge port as the horizontal axis and the single board drying demand coefficient as the vertical axis. A DRI change curve is drawn in the rectangular coordinate system, and a preset DRI curve is drawn at the same time. The DRI change curve and the preset DRI curve are calculated. When the DRI change curve and the preset DRI curve are from the feed port to the first group of cooling fans, the area above the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-exceeding area, and the area below the preset DRI curve, the preset DRI curve and the DRI change curve and the area enclosed are marked as the pre-reducing area. The pre-exceeding area and the pre-reducing area are counted respectively, and the difference between the two is made, and the difference is marked as the adjustment threshold; The corresponding relationship between the adjustment threshold and the change rate of the cooling fan wind speed is set, that is, each unit of positive adjustment threshold corresponds to a decrease of X% in the current cooling fan wind speed, and each unit of negative adjustment threshold corresponds to an increase of Y% in the current cooling fan wind speed, wherein X and Y are both constants. By matching the adjustment threshold with the change rate of the cooling fan wind speed, the wind speed of the first group of cooling fans is adjusted; The wind speed control method of the second group of cooling fans and the third group of cooling fans is the same as that of the first group of fans, wherein the segment of the DRI variation curve selected for the wind speed control of the second group of cooling fans and the preset DRI curve is the distance between the first group of cooling fans and the second group of cooling fans; The segment of the DRI change curve selected for the wind speed control of the third group of cooling fans and the preset DRI curve is the distance between the second group of cooling fans and the third group of cooling fans when adjusting the fans.

3. The control system of a veneer drying conveyor belt according to claim 1, characterized in that: The process of the outgoing inspection module inspecting the dried outgoing boards is as follows: The veneers after drying are tested to obtain the veneer size stability value, the color distribution uniformity value when the veneers are out of the board, and the veneer drying requirement coefficient when the veneers are out of the board. The three are comprehensively analyzed to obtain the veneer quality evaluation coefficient. The quality evaluation coefficient of the veneer is compared with the preset qualified quality evaluation coefficient range. If it is within the range, it indicates that the veneer drying quality is qualified. If it is not within the range, it indicates that the veneer drying quality is unqualified.

4. A control system for a veneer drying conveyor belt according to claim 3, characterized in that: The specific process of obtaining the dimensional stability value of a single board is as follows: The veneer is evenly divided into several test areas according to its size, and the center line of the test area is used as the warping reference line. For each test area, the maximum vertical distance between the warping reference line and the actual wood surface is measured and marked as the warping value H of the test area; The diagonal line of the detection area is used as the distortion reference line, and the difference between the actual distance and the straight-line distance between the distortion reference lines of each detection area is measured and marked as the distortion value T of the detection area; By substituting the warpage value H of the inspection area and the distortion value T of the inspection area into the preset formula: , the dimensional stability value S of the single board is obtained, where wh is the weight coefficient of warpage, wt is the weight coefficient of distortion, i is the label of the inspection area, i=1, 2, 3, ..., n, n is the total number of inspection areas.

5. A control system for a veneer drying conveyor belt according to claim 4, characterized in that: The process of obtaining the color distribution uniformity value when the board is output is as follows: Use a high-definition camera to shoot each inspection area to obtain a single-board image of the inspection area, evenly distribute a number of sampling points on the single-board image of each inspection area, convert the single-board image of each inspection area from the original RGB color space to the LAB color space, and record the L, A, and B channel values ​​of each sampling point in the LAB color space; Get the L, A, and B channel values ​​of each sampling point in the detection area, and calculate the L, A, and B channel values ​​of each sampling point in the detection area to obtain the standard deviation of the L channel value LX, the standard deviation of the A channel value AX, and the standard deviation of the B channel value BX in the detection area. Use the formula , the color distribution uniformity value CUV of the single board is obtained, where b1, b2, and b3 are the preset weight factors of the L, A, and B channels respectively.

6. A control system for a veneer drying conveyor belt according to claim 5, characterized in that: The process of processing qualified and unqualified veneer drying quality is as follows: If unqualified: firstly, take out the single board that is not in the qualified interval value, and then perform a secondary drying operation, and then make the quality evaluation coefficient of the single board subtract from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the single board drying quality deviation value; by matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is output after the match is successful, where T is a constant, and the wind speed adjustment value T is fed back to the drying module, and the drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T; If qualified: a drying good signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the single board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the single board according to the quality evaluation coefficient of the single board; The mapping relationship between the quality assessment coefficient and the cooling fan speed and the conveying speed in the cooling area is set, and then the cooling fan speed and the conveying speed in the cooling area are regulated according to the quality assessment coefficient. When the qualified single board is conveyed out of the cooling area, it will be conveyed to the horizontal conveying device through the board discharge roller device, and then pass through the sorting belt and the board collecting machine to enter the interior of the palletizer. After the palletizer sorts the single boards, the single boards can be discharged from the board discharge port.

7. A control method for a veneer drying conveyor belt, applied to a control system of a veneer drying conveyor belt as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: The loading module controls the wood veneer on the material preparation conveying device to be conveyed to the automatic lifting device, and controls the vacuum suction cup adsorption device to adsorb and load the wood veneer on the automatic lifting device, and collects the initial data of the wood veneer when adsorbing and loading the wood veneer; Step 2: Process the initial data to obtain the veneer drying demand coefficient, and match the veneer drying demand coefficient with the preset veneer drying demand coefficient intervals corresponding to the bottom drying layer, the middle drying layer, and the top drying layer. After the match is successful, the veneer on the vacuum suction cup adsorption device is transported to the corresponding drying layer of the dryer through the swing table distribution device for transportation and drying; Step 3: Extract the mean of the DRI interval values ​​corresponding to the drying layer as the temperature speed value. According to the historical data of the effective drying of the single board by the dryer, establish the mapping relationship between the DRI value and the drying temperature and the conveying speed. According to the temperature speed value, determine the appropriate drying temperature and conveying speed from the mapping relationship. After the first batch of single boards are dried on the drying layer, extract the mean of the DRI values ​​of this batch of single boards as the temperature speed value to re-regulate the drying temperature and conveying speed. Step 4: Count the pre-exceeding area and the pre-reducing area, and make a difference between the two. The difference is marked as the adjustment threshold. The corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan is set. By matching the adjustment threshold with the wind speed change rate of the cooling fan, the wind speed of the first group of cooling fans is adjusted. The wind speed control method of the second group of cooling fans and the third group of cooling fans is the same as that of the first group of fans. Step 5: Comprehensively analyze the dimensional stability of the veneer after drying, the color distribution uniformity of the veneer when the veneer is out, and the veneer drying requirement coefficient when the veneer is out to obtain the veneer quality evaluation coefficient, and judge whether the veneer drying quality is qualified according to the veneer quality evaluation coefficient; If it is not in the qualified interval value: first, the single board that is not in the qualified interval value is taken out, and then a secondary drying operation is performed. Secondly, the quality evaluation coefficient of the single board is subtracted from the minimum value in the preset qualified quality evaluation coefficient interval to obtain the single board drying quality deviation value. By matching the single board drying quality deviation value with the preset multiple groups of adjustment intervals, a wind speed adjustment value T is output after the match is successful, and the wind speed adjustment value T is fed back to the drying module. The drying module resets the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan according to the wind speed adjustment value T; If the value is in the qualified interval: a good drying signal is generated and sent to the drying module. The drying module will maintain the corresponding relationship between the adjustment threshold and the wind speed change rate of the cooling fan. At the same time, the single board will continue to be transported and enter the cooling area. The cooling fan is provided in the cooling area. The cooling fan will cool the single board according to the quality evaluation coefficient of the single board to prevent the single board from getting damp. When qualified veneers are conveyed out of the cooling area, they will be conveyed to the transverse conveying device through the board discharge roller device, and then pass through the sorting belt and the board collector to enter the interior of the palletizer. After the palletizer sorts the veneers, the veneers can be discharged from the board discharge port.

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