Device and method for monitoring stress and strain in real time during bending, heating and forming of bamboo wood

Abstract

The invention discloses a stress-strain real-time monitoring device and a monitoring method during bending and heating forming of bamboo wood, the stress-strain real-time monitoring device comprises a platform support, a force measuring system is arranged on the platform support, and a material clamping system, a bending forming system, a motion control system and the force measuring system are respectively connected with a display system; the material clamping system is used for clamping the two ends of the bamboo wood so as to achieve preliminary bending of the bamboo wood. The bending forming system is used for applying stress to the bamboo wood so that the bamboo wood can be bent. The motion control system is connected with the bending forming system, and the motion control system drives the bending forming system to apply stress to the bamboos; the heating system is arranged on the bending forming system so as to heat the bamboo wood. The force measuring system is used for measuring the stress of the material clamping system and the stress of the bending forming system in real time; the display system is used for observing and recording stress changes and temperature changes in real time. According to the method, the stress-strain change of the bamboo wood in the bending forming state is recorded in real time, and the yield and the overall performance of the bamboo wood bending part are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bamboo processing, and particularly to a device and method for real-time monitoring of stress and strain during the bending and heating forming of bamboo materials. Background Art

[0002] As a sustainable green building material, bamboo can be processed into various specifications of boards and structural components after a series of processes such as removing internal nodes, surface treatment, high-temperature softening, and flattening, due to its characteristics of rapid growth and short life cycle. With the progress of technology, bamboo not only maintains the aesthetic characteristics of natural materials but also enhances its physical and mechanical properties through bending forming technology, effectively improving the service life of bamboo products and showing great market potential.

[0003] During the processing of bamboo slices, such as after operations like gluing and bending, internal stresses will be generated. These stresses are caused by physical deformations (such as bending deformations) or chemical changes (such as the curing of adhesives during the gluing process) of the bamboo slices. Uneven stress release between bamboo slices means that during the process of bamboo slices recovering from the processed state to a relatively stable state, the speed and degree of stress elimination are inconsistent for different bamboo slices or different parts of the same bamboo slice. This uneven stress release will lead to many problems. For example, the bamboo slices may warp and deform, affecting the dimensional accuracy and appearance quality of products (such as bamboo furniture, bamboo handicrafts, etc.). During long-term use, uneven stress release may also lead to a decrease in the structural stability of bamboo products and reduce their service life.

[0004] However, during the bending and heating forming process of bamboo materials, due to the lack of effective means for real-time monitoring of stress and strain, it often leads to improper control of processing conditions (such as temperature and humidity), and then causes problems such as cracking of finished products or gluing defects. These problems not only reduce the quality and durability of bamboo components but also hinder their wide application in industries such as construction and furniture manufacturing.

[0005] For example, in the patent with the patent application number "201110023738.6" and the patent name "A manufacturing method of a bent component for bamboo furniture", although the preparation of bent components can be achieved, during the subsequent gluing process, due to the uneven stress release between bamboo slices, it is easy to cause misalignment at the splicing joints. In addition, traditional preparation processes often involve multiple steps of operations, such as embryo assembly, heating and bending, gluing application, and shaping, which not only have complex technological processes but also require multiple manual interventions, greatly reducing production efficiency.

[0006] Therefore, there is an urgent need for a device for real-time monitoring of stress and strain during the bending and heating forming of bamboo materials. Summary of the Invention

[0007] On the one hand, the present invention provides a real-time stress and strain monitoring device for bamboo bending and heat forming, so as to solve the problems that the stress of bamboo obtained by the existing bamboo bending and heat forming method is uneven and it is easy to misalign in subsequent processes. On the other hand, the present invention provides a monitoring method for the real-time stress and strain monitoring device for bamboo bending and heat forming.

[0008] In the first aspect of the present invention, there is provided a real-time stress and strain monitoring device for bamboo bending and heat forming, including a platform bracket, a material clamping system, a bending and forming system, a motion control system, a heating system, a force measuring system and a display system. The force measuring system, the material clamping system and the bending and forming system are provided on the platform bracket. The material clamping system is arranged on both sides of the bending and forming system. The motion control system and the force measuring system are respectively connected to the display system; The material clamping system is used to clamp both ends of the bamboo, and the material clamping system can rotate within the range of 0-90° and move horizontally to realize the preliminary bending of the bamboo; The bending and forming system is used to apply stress to the bamboo to complete the bending of the bamboo; The motion control system is connected to the bending and forming system, and the motion control system drives the bending and forming system to apply stress to the bamboo; The heating system is arranged on the bending and forming system to realize heating of the bamboo; The force measuring system is used for real-time measurement of the stress of the material clamping system and the stress of the bending and forming system; The display system is used for real-time observation and recording of stress changes and temperature changes.

[0009] For the real-time stress and strain monitoring device for bamboo bending and heat forming, preferably, the material clamping system includes a horizontal moving mechanism, a clamping head and a turntable. The horizontal moving mechanism is arranged on both sides of the platform bracket. The turntable is arranged on the horizontal moving mechanism, and the clamping head is arranged on the turntable. The clamping head can clamp the bamboo to realize the rotation of the turntable and make the bamboo clamped by the clamping head bend.

[0010] For the real-time stress and strain monitoring device for bamboo bending and heat forming, preferably, the horizontal moving mechanism includes a transverse guide rail and a connecting plate. The connecting plate is arranged on the transverse guide rail, and the turntable is arranged on the connecting plate.

[0011] The real-time stress and strain monitoring device for bamboo bending and heat forming. Preferably, the bending and forming system includes a lower clamp, an upper clamp, a push rod, and a vertical guide rail. The horizontal movement mechanism is provided on both sides of the vertical guide rail. The vertical guide rail is arranged on the platform bracket. The lower clamp is arranged on the vertical guide rail below the upper clamp. The lower clamp is connected to the push rod, and the push rod is connected to the motion control system to drive the lower clamp and the upper clamp to clamp the bamboo. The heating system is provided on the upper clamp and / or the lower clamp.

[0012] The real-time stress and strain monitoring device for bamboo bending and heat forming. Preferably, the heating system includes an air outlet pipe and a air supply device. The air outlet pipe is connected to the air supply device, and the air outlet of the air outlet pipe is arranged on the upper clamp and / or the lower clamp.

[0013] The real-time stress and strain monitoring device for bamboo bending and heat forming. Preferably, the motion control system includes a driver, and the driver is respectively connected to the push rod, the horizontal movement mechanism, the clamping head, and the turntable.

[0014] The real-time stress and strain monitoring device for bamboo bending and heat forming. Preferably, the force measuring system is a sensor, and the sensor is arranged on the platform bracket and connected to the display system.

[0015] The second aspect of the present invention provides a monitoring method for the real-time stress and strain monitoring device for bamboo bending and heat forming, which specifically includes the following steps: Place both ends of the bamboo in the material clamping system, and align the bending part of the bamboo with the bending and forming system; The material clamping system realizes the preliminary bending of the bamboo; Heat the bending part of the bamboo through the heating system to soften the bamboo; Clamp the bamboo through the bending and forming system, and cooperate with the material clamping system to obtain the ideal curvature of the bamboo.

[0016] The monitoring method for the real-time stress and strain monitoring device for bamboo bending and heat forming. Preferably, the heating temperature of the heating system is 80 - 150 °C.

[0017] The beneficial effects are: The present invention can track the entire stress release process of bamboo slices after processing. By touching the surface of the bamboo slices with the sensor, the stress data of each part of the bamboo slices can be obtained in real time. These data reflect the change of the internal stress of the bamboo slices. The monitored data can provide a basis for adjusting process parameters, thereby promoting the uniform stress release of the bamboo slices.

[0018] When it is found that the stress release between bamboo slices is uneven, corresponding measures can be taken for timely adjustment based on the data fed back by the stress and strain real-time monitoring device of the present invention. For example, when it is monitored that the stress release of a certain part of the bamboo slices is too fast, the stress release rate can be slowed down by adjusting factors such as environmental temperature and humidity. According to the monitoring data, the placement method of the bamboo slices can be adjusted so that the bamboo slices release stress under a more reasonable spatial layout, avoiding unevenness caused by local stress concentration.

[0019] The present invention plays a key role in monitoring, feedback control and process parameter optimization for the uniformity of stress release of bamboo slices, can effectively solve the technical problem of uneven stress release between bamboo slices, and improve the quality and performance of bamboo products.

[0020] The present invention can record the stress and strain changes of bamboo materials in the bent and formed state in real time. At the same time, it reduces quality problems caused by uneven stress release, improves the yield and overall performance of bamboo bent parts, and thus promotes the application and development of bamboo materials in modern manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is a diagram of the use state of the present invention; Figure 3 is a curve graph of the force value changing with time when the bamboo material is bent and heated and formed; Figure 4 is the initial relaxation modulus of four groups of different materials under two different temperature and pressure holding time conditions.

[0022] 1-1, transverse guide rail; 1-2, connecting plate; 1-3, clamping head; 1-4, turntable; 2-1, lower chuck; 2-2, upper chuck; 2-3, push rod; 2-4, vertical guide rail; 3-1, aluminum plate; 3-2, support feet. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments of the present invention fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0025] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "setting", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] A real-time stress and strain monitoring device for bamboo bending and heating forming provided by the present invention includes a platform bracket, a material clamping system, a bending and forming system, a motion control system, a heating system, a force measuring system, and a display system. The force measuring system, the material clamping system, and the bending and forming system are provided on the platform bracket. The material clamping system is arranged on both sides of the bending and forming system. The motion control system and the force measuring system are respectively connected to the display system. The material clamping system is used to clamp both ends of the bamboo, and the material clamping system can rotate within the range of 0-90° and move horizontally to realize the preliminary bending of the bamboo. The bending and forming system is used to apply stress to the bamboo to complete the bending of the bamboo. The motion control system is connected to the bending and forming system, and the motion control system drives the bending and forming system to apply stress to the bamboo. The heating system is arranged on the bending and forming system to realize heating of the bamboo. The force measuring system is used for real-time measurement of the stress of the material clamping system and the stress of the bending and forming system. The display system is used for real-time observation and recording of stress changes and temperature changes. The present invention can record the stress and strain changes of bamboo in the bending and forming state in real time. At the same time, it reduces the quality problems caused by uneven stress release, improves the yield and overall performance of bamboo bending parts, and further promotes the application and development of bamboo in modern manufacturing.

[0027] The following takes a real-time stress and strain monitoring device for bamboo bending and heating forming as an example to elaborate on the entire technical process in detail.

[0028] Embodiment 1 As Figure 1 and Figure 2As shown in the figure, a real-time stress and strain monitoring device for the bending and heating forming of bamboo materials includes a platform support 3, a material clamping system, a bending forming system, a motion control system, a heating system, a force measuring system, and a display system. The force measuring system, the material clamping system, and the bending forming system are provided on the platform support 3. The material clamping system is arranged on both sides of the bending forming system. The motion control system and the force measuring system are respectively connected to the display system. Among them, the display system is a computer.

[0029] The material clamping system is used to clamp both ends of the bamboo material, and the material clamping system can rotate within the range of 0-90° and move horizontally. The bending forming system is used to apply stress to the bamboo material to complete the bending of the bamboo material. The motion control system is connected to the bending forming system, and the motion control system drives the bending forming system to apply stress to the bamboo material. The heating system is arranged on the bending forming system to heat the bamboo material. The force measuring system is used for real-time measurement of the stress of the material clamping system and the stress of the bending forming system. The display system is used to observe and record the stress change and temperature change in real time.

[0030] Among them, the platform support includes an aluminum plate 3-1 and support feet 3-2. The bottom of the aluminum plate 3-1 is arranged on the support feet 3-2. The length of the aluminum plate 3-1 is 90 mm, the width is 60 mm, and the thickness is 10 mm.

[0031] Continue to refer to Figure 1 As shown in the figure, the material clamping system includes a horizontal moving mechanism, a clamping head 1-3, and a turntable 1-4. The horizontal moving mechanism is arranged on the aluminum plate 3-1. The turntable 1-4 is arranged on the horizontal moving mechanism, and the clamping head 1-3 is arranged on the turntable 1-4. The clamping head 1-3 clamps the bamboo material.

[0032] Among them, the horizontal moving mechanism includes a transverse guide rail 1-1 and a connecting plate 1-2. The transverse guide rail 1-1 is arranged on the aluminum plate 3-1. The connecting plate 1-2 is arranged on the transverse guide rail 1-1, and the turntable 1-4 is arranged on the connecting plate 1-2.

[0033] Among them, the length of the transverse guide rail 1-1 is 100 mm.

[0034] Continue to refer to Figure 1As shown in the figure, the bending and forming system includes a lower chuck 2-1, an upper chuck 2-2, a push rod 2-3, and a vertical guide rail 2-4. The vertical guide rail 2-4 is arranged on the aluminum plate 3-1. The lower chuck 2-1 and the upper chuck 2-2 are arranged on the vertical guide rail 2-4. The horizontal moving mechanisms are arranged on both sides of the vertical guide rail 2-4. And the lower chuck 2-1 is arranged below the upper chuck 2-2. The lower chuck 2-1 is connected to the push rod 2-3. The push rod 2-3 is connected to the motion control system to drive the lower chuck 2-1 and the upper chuck 2-2 to clamp the bamboo. The heating system is arranged on the upper chuck 2-2 and / or the lower chuck 2-1.

[0035] Among them, the stroke of the push rod 2-3 is 80 mm, the precision is 0.1 mm, and the stroke of the vertical guide rail 2-4 is 15 mm.

[0036] Continue to refer to Figure 1 As shown in the figure, the heating system includes an air outlet pipe and a air supply device. The air outlet pipe is connected to the air supply device. The air outlet of the air outlet pipe is arranged on the upper chuck 2-2 and / or the lower chuck 2-1. Among them, the air outlet temperature is 80-150 °C, and the precision is 0.1 °C. Among them, the air supply device is a digital display hot air gun.

[0037] The motion control system includes a driver. The driver is respectively connected to the push rod 2-3, the horizontal moving mechanism, the clamping head 1-3, and the turntable 1-4.

[0038] The force measuring system is a sensor. The sensor is arranged on the platform bracket and connected to the display system. Continue to refer to Figure 1 As shown in the figure, the force measuring system is a 50 kg sensor. The sensor is arranged on the aluminum plate 3-1 and connected to the display system.

[0039] Working process: After the two ends of the bamboo are clamped, they are heated by the heating system. The motion control system drives the center point of the bamboo to move upward along the vertical guide rail 2-4. During this process, the clamping heads 1-3 at both ends of the bamboo rotate around the center, so that the bamboo does not fall off from the clamping heads 1-3. After reaching the required curvature, stop the bamboo from moving upward along the vertical guide rail 2-4 and maintain this state for a certain period of time. At this time, the stress and strain changes of the bamboo in the bending and forming state can be recorded in real time.

[0040] Embodiment 2 A monitoring method for a bamboo bending and heating forming stress and strain real-time monitoring device, including the bamboo bending and heating forming stress and strain real-time monitoring device as described above, specifically including the following steps: S1: Place the two ends of the bamboo in the clamping heads 1-3, and place the part of the bamboo to be bent on the lower chuck 2-1.

[0041] S2: The connecting plate 1-2 moves on the transverse guide rail 1-1, and the turntable 1-4 drives the clamping head 1-3 to rotate, thereby realizing the preliminary bending of the bamboo.

[0042] S3: Heat the part of the bamboo to be bent by the heating system to soften the bamboo.

[0043] S4: The lower clamp 2-1 advances upward along the vertical guide rail 2-4 to realize that the lower clamp 2-1 and the upper clamp 2-2 clamp the center point of the bamboo. Cooperate with the movement of the connecting plate 1-2 on the transverse guide rail 1-1 and the rotation of the turntable 1-4 driving the clamping head 1-3 until the ideal curvature of the bamboo is reached.

[0044] Among them, the heating temperature of the heating system is 80-150 °C.

[0045] Example 3 The sample selects moso bamboo and is made into a sample with a thickness of 1.5 mm, namely "bamboo node yellow", "bamboo node green", "internode green" and "internode yellow". After drying, it is placed between the material clamping systems of the fixed mold.

[0046] Place the four bamboo samples on the devices of Example 1 respectively. During operation, the connecting plate 1-2 moves on the transverse guide rail 1-1, and the turntable 1-4 drives the clamping head 1-3 to rotate, thereby realizing the preliminary bending of the bamboo samples. At this time, the upper clamp 2-2 is in the horizontal initial position and is connected to the display system. The lower clamp 2-1 is lower than the upper clamps 2-2 on both sides. Heat is applied by the heating system. After reaching the predetermined temperature of 120 °C, loading starts. The motion control system drives the lower clamp 2-1 to advance upward along the vertical guide rail 2-4 to realize that the lower clamp 2-1 and the upper clamp 2-2 clamp the center point of the bamboo sample. Cooperate with the movement of the connecting plate 1-2 on the transverse guide rail 1-1 and the rotation of the turntable 1-4 driving the clamping head 1-3. Until the ideal curvature of the bamboo sample is reached, the connecting plate 1-2 and the turntable 1-4 stop moving. The lower clamp 2-1 continues to move slightly upward to fix the bamboo sample between the lower clamp 2-1 and the upper clamp 2-2. At this time, the clamping head 1-3 rotates back to the initial vertical direction and remains in this state for 8 minutes.

[0047] At this time, the stress-strain changes of the bamboo in the bent and formed state can be recorded in real time. As Figure 3 shown, in the initial stage (near 0 s), the force values are all 0 Kg. As time goes by, the force values rise and reach the peak at about 200 s. Among them, the peak value of the "internode green" sample group is the highest, close to 25 Kg, and the peak value of the "bamboo node yellow" sample group is the lowest. After passing the peak value, it should be found through the stress-strain real-time monitoring device in Example 1 that the force values of all sample groups decrease. At this time, it means that stress relaxation occurs in the bamboo. After about 1000 s, the force values of all the lines tend to be stable.

[0048] As Figure 4 shown are the initial relaxation moduli of four different materials, namely "internode green", "internode yellow", "bamboo joint green", and "bamboo joint yellow", under two different temperature and pressure holding time conditions. The initial relaxation modulus refers to the ratio of stress to strain at the beginning of the stress relaxation process (within a very short time after applying the strain), which reflects the ability of the material to resist deformation in the initial state.

[0049] When the temperature is 120 °C and the pressure holding time is 20 minutes, the initial relaxation modulus of the internode green (IO) group is the highest, and that of the bamboo joint yellow (NI) group is the lowest. When the temperature is 150 °C and the pressure holding time is 20 minutes, the initial relaxation modulus of the bamboo joint green (NO) group is the highest, and that of the internode yellow (II) group is the lowest.

[0050] Using materials with a high initial relaxation modulus can ensure the stability and safety of the structure, record the stress-strain changes of bamboo in the bent forming state in real time, calculate the initial relaxation modulus of this material, and at the same time improve the yield and overall performance of bamboo bent parts, thereby promoting the application and development of bamboo in modern manufacturing.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time monitoring device for stress and strain during bamboo bending and heating forming, characterized in that: It includes a platform support, a material clamping system, a bending forming system, a motion control system, a heating system, a force measuring system and a display system. The force measuring system, the material clamping system and the bending forming system are arranged on the platform support. The material clamping system is arranged on both sides of the bending forming system. The motion control system and the force measuring system are respectively connected to the display system. The material clamping system is used to clamp the two ends of the bamboo material, and the material clamping system can rotate within a range of 0-90 degrees and move in a horizontal direction to achieve preliminary bending of the bamboo material; The bending forming system is used to apply stress to the bamboo material so as to make the bamboo material bend; The motion control system is connected to the bending and forming system, and the motion control system drives the bending and forming system to apply stress to the bamboo material; The heating system is arranged on the bending and forming system to heat the bamboo material; The force measuring system is used for real-time measurement of the stress of the material clamping system and the stress of the bending forming system; The display system is used to observe and record stress changes and temperature changes in real time.

2. The real-time monitoring device for stress and strain during bending and heating of bamboo according to claim 1 is characterized in that: The material clamping system includes a horizontal moving mechanism, a clamping head and a turntable. The horizontal moving mechanism is arranged on both sides of the platform bracket. The turntable is provided on the horizontal moving mechanism. The clamping head is provided on the turntable. The clamping head can clamp the bamboo material so that the turntable rotates to bend the bamboo material clamped by the clamping head.

3. The real-time monitoring device for stress and strain during bending and heating of bamboo according to claim 2 is characterized in that: The horizontal moving mechanism comprises a transverse guide rail and a connecting plate. The connecting plate is arranged on the transverse guide rail, and the rotating disk is arranged on the connecting plate.

4. The real-time monitoring device for stress and strain during bending and heating of bamboo material according to claim 3 is characterized in that: The bending and forming system includes a lower clamp, an upper clamp, a push rod and a vertical guide rail, the horizontal moving mechanism is provided on both sides of the vertical guide rail, the vertical guide rail is arranged on the platform bracket, the lower clamp is arranged on the upper clamp arranged on the vertical guide rail, and the lower clamp is arranged below the upper clamp, the lower clamp is connected to the push rod, and the push rod is connected to the motion control system so that the push rod drives the lower clamp and the upper clamp to clamp the bamboo material, and the upper clamp and / or the lower clamp are provided with the heating system.

5. The real-time monitoring device for stress and strain during bending and heating of bamboo according to claim 4 is characterized in that: The heating system comprises an air outlet pipe and an air supply device, wherein the air outlet pipe is connected to the air supply device, and an air outlet of the air outlet pipe is arranged on the upper clamp and / or the lower clamp.

6. The real-time monitoring device for stress and strain during bending and heating of bamboo according to claim 5 is characterized in that: The motion control system comprises a driver, and the driver is connected to the push rod, the horizontal moving mechanism, the clamping head and the turntable respectively.

7. The real-time monitoring device for stress and strain during bending and heating of bamboo according to claim 6 is characterized in that: The force measuring system is a sensor, which is arranged on the platform bracket and connected to the display system.

8. A monitoring method for a real-time monitoring device for stress and strain during bending and heating of bamboo materials according to any one of claims 1 to 7, characterized in that: The specific steps include: Placing two ends of the bamboo material in a material clamping system, with the portion of the bamboo material to be bent aligned with the bending forming system; The material clamping system realizes the initial bending of the bamboo material; The portion of the bamboo material to be bent is heated by a heating system to soften the bamboo material; The bamboo material is clamped by the bending forming system, and cooperated with the material clamping system to obtain an ideal curvature of the bamboo material.

9. The monitoring method of the device for real-time monitoring stress and strain during bending and heating of bamboo materials according to claim 8, characterized in that: The heating temperature of the heating system is 80-150°C.

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