JP7448115B2 - Loading platform for transporting earth and sand, etc. and its manufacturing method - Google Patents

Description

The present invention relates to a loading platform for transporting earth and sand, and a method for manufacturing the same, and more specifically to a loading platform for a dump truck, a shovel section for a power shovel, etc. for transporting earth and sand, and a method for manufacturing these.

In the civil engineering and construction industry, it is essential to transport large amounts of earth and sand cargo, and there are demands for improvement from various viewpoints regarding the transportation of the earth and sand cargo. For example, a steel plate is generally used as a loading platform for a dump truck, but a loading platform made of steel is heavy. On the other hand, the total weight of a vehicle when driving on a road is limited by the Road Traffic Act, and in order to transport more gravel, earth, and the like at one time, it is necessary to reduce the weight of the vehicle itself.

If the loading platform is made of aluminum alloy, it is possible to reduce the weight of the vehicle, but the wear resistance of aluminum alloy material is significantly lower than that of steel material, and gravel and earth are repeatedly loaded and unloaded. Then, the progress of wear becomes serious. Taking this wear into consideration, it is necessary to increase the thickness of the aluminum alloy plate, which not only increases the weight, but also the slipperiness of dirt, etc. on the surface of the aluminum alloy plate is poor, and if the loading platform is not steeply sloped, dirt and sand cargo etc. There was a problem that unloading could not be carried out smoothly.

On the other hand, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 10-181417), the floor surface of a vehicle with an inclined loading platform made of aluminum or aluminum alloy has excellent sliding properties for loaded objects and excellent wear resistance. A loading platform structure for a vehicle with an inclined loading platform has been proposed, in which a plate made of a resin material is attached thereto, and the resin material is made of high molecular weight polyethylene. Furthermore, in the carrier structure, it has also been proposed to use fluororesin as the resin material.

The loading platform structure described in Patent Document 1 maintains the same slipperiness and wear resistance as a dump truck with a steel plate floor structure, can greatly reduce the weight of the entire loading platform, can withstand long-term practical use, and is compliant with the law. It is said to be able to transport more gravel, earth and sand than conventional models within a regulated weight.

Japanese Patent Application Publication No. 10-181417

However, when transporting earth and sand cargo, etc., there is a problem in that residual soil adhering to the loading platform of a dump truck or the like reduces the loadable amount and deteriorates transport efficiency. In addition, due to the deterioration of transportation efficiency, there has been an increase in the number of excessive transportations, a decrease in transportation operation efficiency due to cleaning to remove adhering soil, and an increase in vehicle fuel consumption, so improvements in these areas are desperately needed. ing.

On the other hand, in the loading platform structure described in Patent Document 1, no consideration is given to suppressing residual soil adhering to the loading platform. In addition, the problem of soil adhesion has become more apparent with steel loading platforms, which can ensure better slipperiness than aluminum alloy loading platforms, and even loading platforms with steel plate floor structures are susceptible to deterioration in transport efficiency due to retained soil. cannot be suppressed sufficiently. Specifically, even when a loading platform with a steel plate floor structure is used, on average about 5% of the loaded earth and sand becomes stuck soil. This means that the loading efficiency is 95%, and when considering the total amount of earth and sand transported in the civil engineering and construction industry, the economic loss is extremely large.

Furthermore, in the loading platform structure described in Patent Document 1, the resin plate is mechanically fastened to the floor surface of the aluminum loading platform using rivets or screws. The use of rivets and screws not only increases the weight of the loading platform structure, but also tends to cause cracks in the resin plate, which has lower strength than metal materials, and can be Reliability cannot be guaranteed. Furthermore, it is difficult to completely seal the gap between the fastening portions, and there is a risk that the resin material may break due to intrusion of earth and sand through the gap. Furthermore, when mechanically fastening a resin plate to a metal material using rivets, screws, etc., it is necessary to make the resin material thick in order to ensure the strength and reliability of the joint. As a result, the loading efficiency (volume and weight) of the loading platform deteriorates, and material costs and transportation costs also increase.

Here, from the viewpoint of slipperiness and durability, it is preferable to use a fluororesin plate material as the resin material, but fluororesin is a difficult-to-join material, so it is possible to connect a fluororesin plate to metal without using rivets or screws. At present, there is no simple method of joining materials that can provide high strength and long-term reliability to the joint.

In view of the problems in the prior art as described above, an object of the present invention is to be able to efficiently suppress the adhering residual soil even when compared to a loading platform with a steel plate floor structure, and to prevent the accumulation of soil even when repeatedly transporting earth and sand. It is an object of the present invention to provide a loading platform for transporting earth and sand, etc., which can maintain its effectiveness, and an efficient manufacturing method thereof.

In order to achieve the above object, the present inventor has conducted intensive research on the structure of loading platforms for transporting earth and sand, etc., and as a result, has directly bonded a fluororesin material to the inner surface of a steel loading platform, and removed the fluororesin material from the steel loading platform. We have discovered that it is effective to increase the strength of the joint to the extent that the fluororesin material extends in the form of fibers from the surface of the steel loading platform when it is peeled off, and has arrived at the present invention.

That is, the present invention
A fluororesin material is provided on the inner surface of the steel loading platform,
The steel loading platform and the fluororesin material have a joint portion directly joined to each other,
When the fluororesin material is peeled off from the steel loading platform at the joint, the fluororesin material extends in a fibrous form from the surface of the steel loading platform;
To provide a loading platform for transporting earth and sand, etc., which is characterized by:

In the loading platform for transporting earth and sand of the present invention, the fluororesin material is directly bonded to the inner surface of the steel loading platform without using rivets, screws, etc., so there is no weight increase due to bonding. In addition, the fluororesin material can be made thinner, and weight increase due to bonding of the fluororesin materials can be suppressed. In addition, the fact that the inner surface of the steel loading platform and the fluororesin material are directly bonded means that the inner surface and the surface of the fluororesin material are in complete contact with each other. Even if there is, it will not get between the steel loading platform and the fluororesin material. Furthermore, in the present invention, the term "loading platform for transporting earth and sand, etc." is not limited to the loading platform of a dump truck or the like, but includes, for example, the shovel section of a power shovel, the hopper of an asphalt finisher, and the like.

In addition, the inner surface of the steel loading platform and the fluororesin material are firmly bonded to the extent that when the fluororesin material is peeled off from the steel loading platform, the fluororesin material extends from the surface of the steel loading platform in the form of fibers. It has long-term reliability even in harsh operating environments where earth and sand are repeatedly transported. Here, the loading platform for transporting earth and sand of the present invention can be suitably obtained by the manufacturing method of the loading platform for transporting earth and sand of the present invention, and the strong joint between the surface of the steel loading platform and the fluororesin material is, for example, , it can be formed by direct bonding using laser irradiation.

In the loading platform for transporting earth and sand of the present invention, it is preferable that the thickness of the fluororesin material is 5 mm or less. In the loading platform for transporting earth and sand of the present invention, the fluororesin material is directly bonded to the inner surface of the steel loading platform without using rivets or screws, so the fluororesin material can be made thinner, and the fluororesin material can be made thinner. By setting the thickness of the material to 5 mm or less, it is possible to suppress a reduction in the internal volume and an increase in weight of the loading platform for transporting earth and sand caused by the fluororesin material. The thickness of the fluororesin material is more preferably 0.5 to 1.5 mm, most preferably 0.8 to 1.0 mm.

In the loading platform for transporting earth and sand of the present invention, it is preferable that the surface of the steel loading platform has a metal oxide layer made of metal oxide particles in the joint portion. The metal oxide layer is composed of clusters of metal oxide particles, and the metal oxide layer having such a structure can dramatically improve the bonding strength between the surface of the steel loading platform and the fluororesin material. More specifically, the metal oxide particle clusters promote the dissociation of C—F bonds in the fluororesin material, making it possible to efficiently obtain a strong joint.

Here, the maximum height (Sz) of the surface of the metal oxide layer is preferably 50 nm to 3 μm. By setting the maximum height (Sz) of the surface of the metal oxide particle cluster, which forms the interface to be joined on the metal material side, to 50 nm to 3 μm, it is possible to ensure the adhesion between the metal oxide particle cluster and the fluororesin material. can.

Further, in the loading platform for transporting earth and sand of the present invention, it is preferable that the metal oxide particles have a particle size of 50 to 200 nm. By setting the particle size of the metal oxide particles to 50 nm or more, it becomes easy to set the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more. Further, by setting the particle size of the metal oxide particles to 200 nm or less, it becomes easy to control the maximum height (Sz) of the surface of the metal oxide particle cluster to 3 μm or less. In addition, by setting the particle size of the metal oxide particles to 50 to 200 nm, when the fluororesin material is heated on the surface of the metal oxide particles, dissociation of C-F bonds in the fluororesin material is promoted. can do. The reason why the dissociation of C--F bonds is promoted is not necessarily clear, but it is thought that metal oxide particles having an appropriate curvature (energy state) exhibit a so-called catalytic action.

Further, in the loading platform for transporting earth and sand of the present invention, it is preferable that the fluororesin plate is provided at least at a corner portion of the steel loading platform. Since adhering residual soil due to transporting earth and sand etc. is noticeably formed in the corner portions of the loading platform, by providing a fluororesin plate in this area, it is possible to reduce the adhering residual soil extremely effectively. When mechanically fastening with rivets or screws, it is difficult to join corners compared to flat parts, and there is a gap between the surface of the steel loading platform and the fluororesin material. Easy to occur. On the other hand, in the loading platform for transporting earth and sand of the present invention, the fluororesin material is directly bonded to the inner surface of the steel loading platform, so even a corner portion forms a joint that is equivalent to a flat surface. be able to.

Furthermore, in the loading platform for transporting earth and sand of the present invention, it is preferable that the fluororesin material is polytetrafluoroethylene. Polytetrafluoroethylene has poor reactivity even among fluororesin materials, and can more effectively suppress adhesion of residual soil. Here, although polytetrafluoroethylene is an extremely difficult bonding material, a good bond can be formed by using a direct bonding method using a laser.

Moreover, the present invention
A first step of irradiating the inner surface of the steel loading platform with a pulsed laser in an oxidizing atmosphere to form a surface modified region;
a second step of bringing a fluororesin material into contact with the surface modified region to form a bonded interface;
a third step of increasing the temperature of the interface to be bonded by laser irradiation to achieve bonding,
In the first step, forming a metal oxide particle cluster in which metal oxide particles having a particle size of 5 to 500 nm are continuously joined in the surface modification region,
The maximum height (Sz) of the surface of the metal oxide particle cluster is 50 nm to 3 μm;
A method for manufacturing a loading platform for transporting earth and sand, etc., is also provided.

In the method for manufacturing a loading platform for transporting earth and sand of the present invention, the dissociation of C-F bonds in the fluororesin material in the third step is promoted by metal oxide particle clusters, and a strong joint can be efficiently obtained. . In addition, by setting the maximum height (Sz) of the surface of the metal oxide particle cluster, which is the interface to be joined on the metal material side, to 50 nm to 3 μm, the adhesion between the metal oxide particle cluster and the fluororesin material is ensured. can do.

Many fluororesins do not have melt flowability, and if there are voids at the interface to be joined, even if the voids are minute, they have a large effect on adhesion. On the other hand, when the voids are filled with the fluororesin without any gaps, the presence of the voids contributes to improving the bonding strength. In the metal fluororesin direct bonding method of the present invention, by setting the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more, the strength of the joint can be improved by filling with the fluororesin, By setting the thickness to 3 μm or less, it is possible to prevent the fluororesin from remaining as a void without being filled.

In addition, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, in the first step, the surface of the steel material is irradiated with a pulsed laser in an oxidizing atmosphere to form a surface-modified region. There is no need to use a wet process to form the regions, and a large amount of homogeneous surface-modified regions can be efficiently formed. In addition, the laser equipment used in the first step may be used in the third step, which can improve work efficiency and reduce equipment introduction costs.

The laser used in the first step and the third step is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known lasers can be used, such as a semiconductor laser that can efficiently heat steel materials. can be suitably used.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, it is preferable that the thickness of the fluororesin material be 5 mm or less. In the method of manufacturing a loading platform for transporting earth and sand of the present invention, since the fluororesin material is directly bonded to the inner surface of the steel loading platform using laser irradiation, the fluororesin material can be made thinner. By setting the thickness to 5 mm or less, it is possible to suppress a reduction in the internal volume and an increase in weight of the platform for transporting earth and sand due to the fluororesin material. The thickness of the fluororesin material is more preferably 0.5 to 1.5 mm, most preferably 0.8 to 1.0 mm.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, it is preferable that the metal oxide particles have a particle size of 50 to 200 nm. By setting the particle size of the metal oxide particles to 50 nm or more, it becomes easy to set the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more. Further, by setting the particle size of the metal oxide particles to 200 nm or less, it becomes easy to control the maximum height (Sz) of the surface of the metal oxide particle cluster to 3 μm or less. In addition, by setting the particle size of the metal oxide particles to 50 to 200 nm, when the fluororesin material is heated on the surface of the metal oxide particles, dissociation of C-F bonds in the fluororesin material is promoted. can do. The reason why the dissociation of C--F bonds is promoted is not necessarily clear, but it is thought that metal oxide particles having an appropriate curvature (energy state) exhibit a so-called catalytic action.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, in the third step, the C--F bond of the fluororesin material is dissociated by the catalytic action of the metal oxide particles, and the carboxyl produced by the dissociation is It is preferable to bond a functional group such as a group with a metal element contained in the steel material. The C--F bonds in fluororesin materials are strong and are extremely difficult to dissociate, but by utilizing the catalytic action of metal oxide particles, the C--F bonds can be efficiently dissociated. Further, by dissociating the C—F bond in the vicinity of the metal oxide particles, carboxyl groups and the like can be bonded to the metal elements contained in the metal oxide particles. In addition, in the present invention, bonding is achieved by combining a functional group such as a carboxyl group derived from a fluororesin material with a metal element contained in the steel material, but the term "metal element contained in the steel material" In the surface modified region, it means a metal element derived from a steel material contained in metal oxide particles.

In the method for manufacturing a loading platform for transporting earth and sand of the present invention, it is preferable that the surface modified region has an area of 20% or more of the interface to be joined. By setting the surface modified region to an area of 20% or more of the interface to be joined, high joint strength and reliability can be ensured for the entire joint.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, it is preferable that the irradiation energy of one pulse of the pulsed laser used in the first step is 0.2 to 1.0 mj. By setting the irradiation energy of one pulse of the pulsed laser to 0.2 to 1.0 mj, it is possible to form metal oxide particle clusters in which metal oxide particles having a particle size of 5 to 500 nm are continuously joined in the irradiation area. At the same time, the maximum height (Sz) of the surface of the metal oxide particle cluster can be set to 50 nm to 3 μm.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, it is preferable that in the third step, a pressure of 5 MPa or more is applied to the interface to be joined. By applying a pressure of 5 MPa or more to the interface to be joined in the third step, the fluororesin material and the steel material (metal oxide particle cluster) can be brought into close contact, and a strong joint can be obtained. In addition, even if bubbles or the like are formed at the joint as the temperature rises, the bubbles can be discharged out of the system.

Further, in the method for manufacturing a loading platform for transporting earth and sand of the present invention, in the third step, when the fluororesin material is transparent, the laser is irradiated from the fluororesin material side, so that the fluororesin material is opaque. In this case, it is preferable to irradiate the laser from the steel material side. If the fluororesin material is transparent, the temperature of the interface to be joined can be efficiently raised by irradiating the laser from the fluororesin material side, and when the fluororesin material is opaque, by irradiating the laser from the steel material side. can. Moreover, by irradiating the laser from the steel material side, it can be used as a material to be joined regardless of the type of fluororesin material. Furthermore, by heating from the steel material side, a space can be provided on the fluororesin material side, and if necessary, pressure can be applied from the surface of the fluororesin material.

For example, a semiconductor laser that forms a rectangular beam can be used as the laser used in the third step. Here, since fluororesin, especially PTFE, does not have thermal fluidity, it is difficult to form a good adhesion interface even when there is a very small gap of several micrometers at the interface to be joined, and the metal material It is not possible to achieve bonding with. Therefore, in order to bring the heated fluororesin and metal surface into close contact, in the third step, the temperature of the bonding interface is raised to the optimum temperature by laser irradiation, and then pressure is immediately applied to promote close contact between the fluororesin and the metal surface. It is preferable to apply it.

According to the loading platform for transporting earth and sand of the present invention and its manufacturing method, it is possible to efficiently suppress adhering residual soil even when compared to loading platforms with a steel plate floor structure, and the said effect can be maintained even when earth and sand are repeatedly transported. It is possible to provide a loading platform for transporting earth and sand that can be maintained and an efficient manufacturing method thereof.

FIG. 1 is a schematic diagram showing an example of a loading platform for transporting earth and sand, etc. of the present invention. It is a process diagram of the manufacturing method of the loading platform for transporting earth and sand, etc. of the present invention. This is a SEM observation image of a surface modified region formed on the surface of a stainless steel material. It is a TEM observation image of a cross section of a surface modified region. It is an appearance photograph of the metal fluororesin bonded body obtained in the example. This is a photograph of the appearance of a metal-fluororesin bonded body after a shear tensile test. This is a STEM-EDS analysis result of a peeled region of a metal-fluororesin bonded body. 3 is a photograph of the appearance of a dump truck bed to which a fluororesin material is attached in Example 2. This is the situation of the dump truck platform at the maximum inclination in Example 2. It is the situation of the corner part of the dump truck loading platform at the time of the maximum inclination in Example 2. This is the situation of the dump truck platform at maximum inclination in a comparative example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, typical embodiments of a loading platform for transporting earth and sand and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these. In the following description, the same or equivalent parts are given the same reference numerals, and redundant descriptions may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions of the illustrated components and their ratios may differ from the actual ones.

(1) Loading platform for transporting earth and sand, etc. FIG. 1 is a schematic diagram showing an example of a loading platform for transporting earth, sand, etc. of the present invention. The loading platform 2 for transporting earth and sand, etc. shown in FIG. 1 is a loading platform for a dump truck, and a fluororesin material 6 is directly bonded to the inner surface of the steel loading platform 4. In the loading platform 2 for transporting earth and sand, the fluororesin material 6 is directly bonded to the inner surface of the steel loading platform 4 without using rivets, screws, etc., so there is no increase in weight due to bonding. Here, the entire inner surface of the steel loading platform 4 may be covered with the fluororesin material 6, but it is preferable to cover at least the inner corner portions of the steel loading platform 4 with the fluororesin material 6.

The thickness of the fluororesin material 6 is not particularly limited as long as it does not impair the effects of the present invention, but it is preferably 5 mm or less, more preferably 0.5 to 1.5 mm, and 0.8 to 1.5 mm. It is most preferable to set it to .0 mm. By setting the thickness of the fluororesin material 6 to 0.5 mm or more, it is possible to suppress a decrease in slip resistance due to wear and friction of the fluororesin material during long-term use, and by setting it to 5 mm or less, the volume can be reduced. Also, it is possible to suppress a decrease in loading efficiency due to an increase in weight.

Furthermore, there is no need for a joint to be formed on the entire surface of the inner surface of the steel loading platform 4 and the fluororesin material 6, and the fluororesin material 6 does not peel off under the usage conditions, ensuring long-term reliability. What is necessary is to form a joint part. Further, by forming a joint at the outer edge of the fluororesin material 6, it is possible to prevent dirt and the like from entering between the steel loading platform 4 and the fluororesin material 6.

Moreover, when the fluororesin material 6 is forcibly peeled off from the steel loading platform 4, the fluororesin originating from the fluororesin material 6 extends from the surface of the steel loading platform 4 in the form of fibers. This means that the fluororesin material 6, which is a difficult-to-join material, is chemically and firmly joined to the surface of the steel loading platform 4, which is completely different from mechanical fastening.

The method for confirming the fluororesin material 6 extending in the form of fibers from the surface of the steel loading platform 4 is not particularly limited, and may be observed using various conventionally known methods. For example, the surface of the steel loading platform 4 from which the fluororesin material 6 has been peeled off may be observed using an appropriate microscope, etc. When observing the loading platform, a portable microscope can be used, and if you wish to observe in more detail. This can be done by appropriately cutting the relevant portion of the steel loading platform 4 and observing it at high magnification using a scanning electron microscope.

Furthermore, at the bonding interface, the C--F bonds of the fluororesin material 6 change to bonds such as C--OO, C--O, and C=O. As a result, for example, when the fluororesin material 4 extending in the form of fibers from the surface of the steel loading platform 4 is subjected to elemental analysis, the amount of F detected is extremely small compared to C and O.

Moreover, in the joint part of the loading platform 2 for transporting earth and sand, it is preferable to have a metal oxide layer made of metal oxide particles on the surface of the steel loading platform 4. The metal oxide layer is composed of clusters of metal oxide particles, and the metal oxide layer having such a structure can dramatically improve the bonding strength between the surface of the steel loading platform 4 and the fluororesin material 6. . More specifically, the metal oxide particle cluster promotes the dissociation of the C—F bond in the fluororesin material 6, and a strong joint can be efficiently obtained.

The maximum height (Sz) of the surface of the metal oxide layer is preferably 50 nm to 3 μm. Adhesion between the metal oxide particle cluster and the fluororesin material 6 is ensured by setting the maximum height (Sz) of the surface of the metal oxide particle cluster, which is the interface to be joined on the side of the steel loading platform 4, to 50 nm to 3 μm. can do.

Further, the particle size of the metal oxide particles is preferably 50 to 200 nm. By setting the particle size of the metal oxide particles to 50 nm or more, it becomes easy to set the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more. Further, by setting the particle size of the metal oxide particles to 200 nm or less, it becomes easy to control the maximum height (Sz) of the surface of the metal oxide particle cluster to 3 μm or less. In addition, by setting the particle size of the metal oxide particles to 50 to 200 nm, when the fluororesin material 6 is heated on the surface of the metal oxide particles, dissociation of C--F bonds in the fluororesin material 6 can be prevented. can be promoted. The reason why the dissociation of C--F bonds is promoted is not necessarily clear, but it is thought that metal oxide particles having an appropriate curvature (energy state) exhibit a so-called catalytic action.

Moreover, in the loading platform 2 for transporting earth and sand, it is preferable that the fluororesin material 6 is polytetrafluoroethylene (PTFE, melting point: 327° C.). Polytetrafluoroethylene has poor reactivity even among fluororesin materials, and can more effectively suppress adhesion of residual soil. Here, although polytetrafluoroethylene is an extremely difficult bonding material, a good bond can be formed by using a direct bonding method using a laser. Other fluororesin materials include, for example, polychlorotrifluoroethylene (PCTFE, melting point: 220°C), polyvinylidene fluoride (PVDF, melting point: 151-178°C), polyvinyl fluoride (PVF, melting point: 203°C), Tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point: 250-275°C), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, melting point: 302-310°C), tetrafluoroethylene-ethylene copolymer (ETFE, melting point: 218-270°C), tetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), chlorotrifluoroethylene-ethylene copolymer (ECTFE, melting point: 245°C), etc. be able to.

(2) Method for manufacturing a loading platform for transporting earth and sand The main feature of the method for manufacturing a loading platform for transporting earth and sand of the present invention is that a fluororesin material is directly bonded to the inner surface of the steel loading platform. Therefore, the manufacturing method of the steel loading platform, the processing method of the fluororesin material, etc. are not particularly limited as long as they do not impair the effects of the present invention, and those obtained by various conventionally known processing methods and manufacturing methods may be used. can do.

FIG. 2 is a process diagram of the method for manufacturing a loading platform for transporting earth and sand according to the present invention. The method for manufacturing a loading platform for transporting earth and sand of the present invention includes a first step (S01) of irradiating the inner surface of a steel loading platform with a pulsed laser in an oxidizing atmosphere to form a surface modified region; A second step (S02) of bringing a fluororesin material into contact with the material to form a bonded interface, and a third step (S03) of heating the bonded interface by laser irradiation to achieve bonding. There is. Each step will be explained in detail below.

(1-1) First step (S01: Surface modified region formation step)
The first step (S01) is a step for obtaining a surface modified region that contributes to the formation of a strong bonding interface. In the surface modification region, there is a metal oxide particle cluster formed by continuously joining metal oxide particles having a particle size of 5 to 500 nm, and a metal oxide particle cluster with a maximum height (Sz) of 50 nm to 3 μm. Form particle clusters.

By setting the maximum height (Sz) of the surface of the metal oxide particle cluster, which becomes the interface to be joined on the metal material side, to 50 nm to 3 μm, the connection between the metal oxide particle cluster and the fluororesin material in the third step (S03) is Adhesion can be ensured. By setting the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more, the strength of the joint can be improved by filling with fluororesin, and by setting it to 3 μm or less, the strength of the joint can be improved by filling with fluororesin. It is possible to suppress the occurrence of voids remaining as they are. A more preferable maximum surface height (Sz) of the metal oxide particle cluster is 100 nm to 2 μm, and a most preferable maximum height (Sz) is 200 nm to 1 μm.

Further, it is preferable that the particle size of the metal oxide particles is 50 to 200 nm. By setting the particle size of the metal oxide particles to 50 nm or more, it becomes easy to set the maximum height (Sz) of the surface of the metal oxide particle cluster to 50 nm or more. Further, by setting the particle size of the metal oxide particles to 200 nm or less, it becomes easy to control the maximum height (Sz) of the surface of the metal oxide particle cluster to 3 μm or less. In addition, by setting the particle size of the metal oxide particles to 50 to 200 nm, when the fluororesin material is heated on the surface of the metal oxide particles, dissociation of C-F bonds in the fluororesin material is promoted. can do.

In the first step (S01), specifically, a pulsed laser is irradiated onto the inner surface of the steel loading platform in an oxidizing atmosphere. The laser used in the first step is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known lasers can be used. For example, a semiconductor laser that can efficiently heat steel materials is preferably used. be able to.

The irradiation energy of one pulse of the pulsed laser is preferably 0.2 to 1.0 mj. By setting the irradiation energy of one pulse of the pulsed laser to 0.2 to 1.0 mj, it is possible to form metal oxide particle clusters in which metal oxide particles having a particle size of 5 to 500 nm are continuously joined in the irradiation area. At the same time, the maximum height (Sz) of the surface of the metal oxide particle cluster can be set to 50 nm to 3 μm.

Further, the type of oxidizing atmosphere is not particularly limited as long as it does not impair the effects of the present invention, and it may be an atmosphere in which metal oxide particle clusters are formed on the surface of the steel material by irradiation with a pulsed laser. All you have to do is process it inside.

Further, the surface modified region may be formed at the interface of the steel materials to be joined, but it is preferable that the surface modified region has an area of 20% or more of the interface to be joined. By setting the surface modified region to an area of 20% or more of the interface to be joined, high joint strength and reliability can be ensured for the entire joint. Further, the surface modified region may be formed in a planar shape, or may be formed into a suitable pattern such as a line shape, for example.

(1-2) Second process (S02: bonded interface formation process)
In the second step (S02), the steel material (inner surface of the steel loading platform) on which the surface-modified region was formed in the first step (S01) is brought into contact with the fluororesin material to form a bonded interface. This is a process to make it happen.

In addition, when making a lap joint between steel materials and fluororesin materials, it is possible to bond the materials together by placing a heat-resistant glass plate, etc. in contact with the surface of one or both of the materials to be joined, and restraining the entire surface. can be brought into closer contact with each other, and displacement of the bonded interface during laser irradiation can be suppressed. Note that it is preferable to use heat-resistant glass that has excellent laser transmittance. Moreover, even without using heat-resistant glass, by applying pressure to bring both members into close contact using a steel roller, it is possible to achieve close contact between the members immediately after heating by laser irradiation. After achieving close contact after heating, it is desirable to cool the temperature of the bonding interface to below the melting point of the fluororesin within an appropriate time.

The fluororesin used as the material to be joined is not particularly limited as long as it does not impair the effects of the present invention, and conventionally known fluororesins can be used. Examples of the fluororesin include polytetrafluoroethylene (PTFE, melting point: 327°C), polychlorotrifluoroethylene (PCTFE, melting point: 220°C), polyvinylidene fluoride (PVDF, melting point: 151 to 178°C), Polyvinyl fluoride (PVF, melting point: 203°C), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point: 250-275°C), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, melting point: 302-275°C) 310°C), tetrafluoroethylene-ethylene copolymer (ETFE, melting point: 218-270°C), tetrafluoroethylene-perfluorodioxole copolymer (TFE/PDD), chlorotrifluoroethylene-ethylene copolymer (ECTFE, melting point: 245°C), etc. However, since the fluororesin joining method of the present invention allows a joint with excellent high-temperature strength to be obtained without using an adhesive, polytetra It is preferable to use fluoroethylene (PTFE, melting point: 327°C). By using polytetrafluoroethylene, it is possible to extremely efficiently reduce the amount of residual soil on steel loading platforms.

The thickness of the fluororesin material is not particularly limited as long as it does not impair the effects of the present invention, but it is preferably 5 mm or less, more preferably 0.5 to 1.5 mm, and 0.8 to 1.5 mm. Most preferably, it is 0 mm. By setting the thickness of the fluororesin material 6 to 0.5 mm or more, it is possible to suppress a decrease in slip resistance due to wear and friction of the fluororesin material during long-term use, and by setting it to 5 mm or less, the volume can be reduced. Also, it is possible to suppress a decrease in loading efficiency due to an increase in weight.

The material of the steel loading platform to be welded is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known steel materials can be used, such as stainless steel, carbon steel, tool steel, etc. can be used. From the viewpoint of corrosion resistance, it is preferable to use stainless steel, and from the viewpoint of wear resistance, it is preferable to use tool steel.

(1-3) Third step (S03: temperature raising step)
The third step (S03) is a step of increasing the temperature of the bonded interface formed in the second step (S02) by laser irradiation to achieve bonding.

In the third step (S03), if the fluororesin material is transparent, it is preferable to irradiate the laser from the fluororesin material side, and if the fluororesin material is opaque, it is preferable to irradiate the laser from the steel material side. If the fluororesin material is transparent, the temperature of the interface to be joined can be efficiently raised by irradiating the laser from the fluororesin material side, and when the fluororesin material is opaque, by irradiating the laser from the steel material side. can. Moreover, by irradiating the laser from the steel material side, it can be used as a material to be joined regardless of the type of fluororesin material. Furthermore, by heating from the steel material side, a space can be provided on the fluororesin material side, and if necessary, pressure can be applied from the surface of the fluororesin material.

In the third step (S03), it is preferable to apply a pressure of 5 MPa or more to the interface to be joined. By applying a pressure of 5 MPa or more to the interface to be joined, the fluororesin material and the steel material (metal oxide particle clusters formed on the surface of the steel material) can be brought into close contact, and a strong joint can be obtained. can. In addition, even if bubbles or the like are formed at the joint as the temperature rises, the bubbles can be discharged out of the system.

Although the joint where the fluororesin material and steel material are directly joined via metal oxide particle clusters has sufficiently high strength, it is possible to reduce the variation in quality by adding a pressurizing process. can. By applying the pressure, for example, the softened fluororesin material spreads beyond the range of the heat affected zone of the steel material, so that the bonding interface between the steel material and the fluororesin material can be expanded.

When applying pressure to the interface to be joined, in the second step (S02), the surface of one or both of the materials to be joined is brought into contact with a heat-resistant glass plate or the like to restrain the entire surface, thereby making it easier to press the interface to be joined. can be pressed.

Process parameters related to laser irradiation, such as laser output, scanning speed, and focal length, should be selected appropriately depending on the type and size of the materials to be joined, the area of the interface to be joined, and the mechanical properties required for the joint. do it.

Although typical embodiments of the present invention have been described above, the present invention is not limited to these, and various design changes are possible, and all such design changes are included within the technical scope of the present invention. It will be done.

≪Example 1≫
[Direct bonding of fluororesin material to steel material]
Using the method of manufacturing a loading platform for transporting earth and sand of the present invention, a fluororesin material and a stainless steel material (inner surface of a steel loading platform) were directly joined. The fluororesin material is polytetrafluoroethylene (PTFE), and Naflon TOMBO No. 1 manufactured by Nichias Corporation is used. 9000 (plate thickness: 1 mm) was cut into 25 mm x 50 mm to obtain one of the materials to be joined. Further, the steel material was SUS304 stainless steel (plate thickness 0.5 mm), and in this example, it was cut into 25 mm x 100 mm to be used as the other material to be joined corresponding to the inner surface of the steel loading platform.

Laser irradiation was applied to the region of the stainless steel material that would become the interface to be joined in the atmosphere to form a surface modified region (first step). A YLP pulse laser manufactured by IPG was used as the laser, and the laser irradiation conditions were: average output: 50 W (energy of one pulse: 1 mj), focus diameter: 59 μm, and scanning speed: 15000588.5 μm/s. Further, the pitch and offset of laser irradiation were both 60 μm, and a surface modified region was formed in the entire area of the interface to be bonded.

FIG. 3 shows SEM photographs (low magnification and high magnification) of the surface modified region formed on the surface of the stainless steel material. For SEM observation, JSM-7100F manufactured by JEOL Ltd. was used. A high-magnification SEM photograph shows that clusters are formed in the surface-modified region by continuously bonding particles having a particle size of about 5 to 100 nm. Furthermore, when the cluster was subjected to SEM-EDS analysis using an energy dispersive X-ray analyzer (JED-2300 Analysis Station Plus) attached to the SEM, metal elements such as O and Fe were mainly detected. Specifically, the point analysis results for clusters are: Fe: 28.0 at%, O: 26.2 at%, Cr: 21.9 at%, C: 17.2 at%, Ni: 4.8 at%, Mn: 1 .5at%, Si:0.4at%. These results indicate that clusters in which fine metal oxide particles are continuously joined are formed in the surface-modified region.

TEM observation was performed on a cross section of the surface modified region. JEM-ARM200F manufactured by JEOL Ltd. was used for TEM observation. The obtained TEM observation image is shown in FIG. It can be seen that the surface of the cluster made of metal oxide particles is relatively smooth, and the maximum height (Sz) is 50 nm to 3 μm.

After the first step, a PTFE plate was stacked on the surface-modified region (second step), and a laser was irradiated from the stainless steel plate side to obtain a metal-fluororesin bonded body (third step). In the third step, a 4 kW semiconductor laser manufactured by Laserline was used, a zoom homogenizer was used in the optical system to form a 3 mm x 40 mm line laser, and the laser was scanned over 25 mm at an output of 200 W and a scanning speed of 0.5 mm/s. Further, in the third step, a pressure of about 5 MPa was applied to the interface to be bonded. The bonded portion of the metal-fluororesin bonded body has a bonding length of 15 mm with respect to a plate width of 25 mm, and a bonding area of 25 mm x 15 mm is formed. A photograph of the appearance of the obtained metal-fluororesin bonded body is shown in FIG.

Five metal fluororesin bonded bodies were produced in the same manner, and the shear tensile strength of the resulting bonded bodies was measured. Before the shear tensile test, the metal fluororesin bonded body was held at -30°C for 10 minutes, and the tensile speed was 10 mm/min. The obtained shear tensile properties are shown in Table 1. Furthermore, a photograph of the appearance of the metal-fluororesin bonded body after the shear tensile test is shown in FIG.

The PTFE plates of all metal-fluororesin bonded bodies were elongated, and the load showed a high value of 500N or more. It can be seen that the PTFE plate was broken in the shear tensile test, indicating that the bonding strength exceeded the material strength.

In addition, regarding the metal-fluororesin bonded body, the stainless steel plate and the PTFE plate were forcibly separated, and the sample immediately before complete separation was analyzed by STEM-EDS. The obtained STEM-EDS analysis results are shown in FIG. The PTFE is elongated in the form of a fiber while being bonded to the metal oxide particle cluster, and voids are created at the bonding interface. Furthermore, in EDS analysis, C and O were clearly detected, but F was hardly detected. The results suggest that the C--F bonds in PTFE are changed to bonds such as C--O--O, C--O, and C=O.

≪Example 2≫
[Performance evaluation of loading platform for transporting earth and sand]
Using the joining method described in Example 1, a fluororesin material (PTFE) was directly joined to the inner corner of a steel dump truck bed. Figure 8 shows a photograph of the exterior of a dump truck bed with fluororesin material attached.

Next, in order to evaluate the adhesion of earth and sand to the dump truck bed, the dump truck bed was filled with silty clay, and then the dump truck bed was tilted to the maximum extent possible. FIG. 9 shows the condition of the dump truck bed when the dump truck is tilted, and FIG. 10 shows the condition of the corner of the dump truck bed. It can be seen from FIGS. 9 and 10 that the fluororesin material very effectively suppresses the adhesion of silty clay soil.

≪Comparative example≫
The adhesion of earth and sand to the dump truck bed was evaluated in the same manner as in Example 2, except that the fluororesin material was not bonded to the inner corner of the steel dump truck bed.

Figure 11 shows the situation when the dump truck platform is tilted to its maximum extent. It can be seen that a large amount of silty clay soil is attached to the corner of the loading platform as residual soil.

2... Loading platform for transporting earth and sand, etc.
4...Steel loading platform,
6...Fluororesin material.

Claims (13)

A fluororesin material is provided on the inner surface of the steel loading platform,
The steel loading platform and the fluororesin material have a joint portion directly joined to each other,
When the fluororesin material is peeled off from the steel loading platform at the joint, the fluororesin material extends from the surface of the steel loading platform in the form of fibers,
having a metal oxide layer made of metal oxide particles on the surface of the steel loading platform in the joint;
A loading platform for transporting earth and sand . The thickness of the fluororesin material is 5 mm or less,
The loading platform for transporting earth and sand according to claim 1. The metal oxide particles have a particle size of 50 to 200 nm;
The earth and sand transport platform according to claim 1 or 2 , characterized in that: the fluororesin material is provided at least at a corner of the steel loading platform;
The loading platform for transporting earth and sand according to any one of claims 1 to 3 , characterized in that: the fluororesin material is polytetrafluoroethylene;
The loading platform for transporting earth and sand according to any one of claims 1 to 4 , characterized by: A first step of irradiating the inner surface of the steel loading platform with a pulsed laser in an oxidizing atmosphere to form a surface modified region;
a second step of bringing a fluororesin material into contact with the surface modified region to form a bonded interface;
a third step of increasing the temperature of the interface to be bonded by laser irradiation to achieve bonding;
In the first step, forming a metal oxide particle cluster in which metal oxide particles having a particle size of 5 to 500 nm are continuously joined in the surface modification region,
The maximum height (Sz) of the surface of the metal oxide particle cluster is 50 nm to 3 μm;
A method for manufacturing a loading platform for transporting earth and sand , characterized by: The thickness of the fluororesin material is 5 mm or less,
The method for manufacturing a loading platform for transporting earth and sand according to claim 6 . The metal oxide particles have a particle size of 50 to 200 nm;
8. The method for manufacturing a loading platform for transporting earth and sand according to claim 6 or 7 . The surface modified region has an area of 20% or more of the interface to be joined;
The method for manufacturing a loading platform for transporting earth and sand according to any one of claims 6 to 8 , characterized in that: In the third step, the C-F bond of the fluororesin material is dissociated by the catalytic action of the metal oxide particles, and the functional group generated by the dissociation is bonded to the metal element contained in the steel loading platform. ,
The method for manufacturing a loading platform for transporting earth and sand according to any one of claims 6 to 9 . The irradiation energy of one pulse of the pulsed laser is set to 0.2 to 1.0 mj,
The method for manufacturing a loading platform for transporting earth and sand according to any one of claims 6 to 10 , characterized in that: In the third step, applying a pressure of 5 MPa or more to the interface to be joined;
The method for manufacturing a loading platform for transporting earth and sand according to any one of claims 6 to 11 , characterized in that: The fluororesin material is polytetrafluoroethylene;
13. The method for manufacturing a loading platform for transporting earth and sand according to any one of claims 6 to 12 .