JP4178964B2 - Medical equipment top plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a top plate suitable for medical X-ray equipment such as an X-ray imaging apparatus and a CT scanner, which has excellent bending strength.
[0002]
[Prior art]
A top plate of medical X-ray equipment such as an X-ray imaging apparatus and a CT scanner is required to have a high bending strength so as not to interfere with imaging even when a load of 1 ton is equally distributed on the upper surface. ing. In particular, in recent years, there is a strong demand for a longer top plate and improved durability in order to photograph a wide range at once.
[0003]
Many of such top plates are configured as a sandwich structure of a core made of hard plastic foam and a skin made of FRP (fiber reinforced plastic). In the top plate having such a structure, the above-mentioned requirements are met by increasing the thickness of the core and the thickness of the skin. However, the increase in thickness not only causes an increase in weight and an increase in price, but also transmits X-rays. Since the rate decreases, it is necessary to increase the X-ray intensity, and there is a problem that the X-ray exposure dose of the subject increases. Therefore, when used, that is, when the bending moment is applied, the upper skin that becomes the convex side (tensile side) is made of CFRP (carbon fiber reinforced plastic) with carbon fiber that can exhibit high tensile strength and tensile modulus, and the concave side It has been proposed that the lower skin to be (compressed side) is made of CFRP of carbon fiber capable of expressing high compressive strength and compressive modulus (for example, see Patent Document 1). This is because, as the whole top plate, tensile stress is generated on the convex side and compressive stress is generated on the concave side, so high strength can be achieved efficiently by using carbon fibers suitable for each. It is to try. However, even if it is the whole top plate, if attention is paid only to the skin, as is apparent from the mechanics, even in the upper skin on the convex side, compressive stress is generated on the inner layer side. Accordingly, it is not always efficient to select carbon fibers by paying attention only to tensile strength and tensile modulus. Similarly, in the lower skin, which is the concave side, tensile stress is generated on the inner layer side. Therefore, when carbon fiber is selected by paying attention only to compressive strength and compressive elastic modulus, the effect of the entire skin is reduced. Will be. Such a tendency becomes more prominent as the difference in rigidity between the core and the skin increases.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 5-62208
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems of the conventional top plate, and an object thereof is to provide a top plate for medical equipment with higher strength.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a sandwich structure of a core and a skin made of FRP, the skin includes a plurality of FRP layers, and becomes a tension side when a bending moment acts. Provides a medical device top plate in which an FRP layer having a higher compressive strength than an FRP layer positioned next to the FRP layer is disposed on the FRP layer positioned closest to the core. The FRP layer located closest to the core is preferably the FRP layer having the highest compressive strength among the plurality of FRP layers.
[0007]
In order to achieve the above object, the present invention has a sandwich structure of a core and an FRP skin, the skin includes a plurality of FRP layers, and becomes a compression side when a bending moment acts. The skin is provided with a medical device top plate in which an FRP layer having a higher tensile strength than an FRP layer positioned next to the FRP layer is disposed on the FRP layer positioned closest to the core. The FRP layer located closest to the core is preferably the FRP layer having the highest tensile strength among the plurality of FRP layers.
[0008]
Further, the present invention has a sandwich structure of a core and an FRP skin as the most preferable embodiment, and the skin includes a plurality of FRP layers, and the skin that becomes the tension side when a bending moment is applied to the skin. An FRP layer having a higher compressive strength than the FRP layer positioned next to the FRP layer is disposed on the FRP layer positioned closest to the core side, and the skin that becomes the compression side when a bending moment is applied has the most core side A medical device top plate is provided in which an FRP layer having a higher tensile strength than an FRP layer positioned next to the FRP layer is disposed on the FRP layer positioned on the surface. In this case, the FRP layer located on the most core side of the skin that becomes the tension side when the bending moment is applied is the FRP layer having the highest compressive strength among the plurality of FRP layers, and when the bending moment is applied. The FRP layer located on the most core side of the skin on the compression side is preferably the FRP layer having the highest tensile strength among the plurality of FRP layers.
[0009]
In the above, the core is like a rigid plastic foam such as polyurethane foam, polystyrene foam, polyvinyl chloride foam, acrylic foam, polymethacrylimide foam, cellulose acetate foam, epoxy foam, phenol foam and the like. These rigid foams generally have a shear modulus of 100 GPa or less. The size is about 30 to 70 mm, the width is about 200 to 500 mm, and the length is more than 2,000 mm depending on the application.
[0010]
The skin includes a plurality of FRP layers. That is, it has a layered structure. The number of layers is about 2 to 6 layers, although it depends on the application, the size of the top plate, the type, characteristics, and form of the reinforcing fibers used. The thickness is usually about 1 to 8 mm. The surface of the skin may be painted or may be the surface of the matrix resin itself forming the FRP layer.
[0011]
The FRP layer includes a reinforcing fiber and a matrix resin. As the reinforcing fiber, at least one of carbon fiber (including graphite fiber), aramid fiber, high-strength polyethylene fiber, glass fiber, and boron fiber can be used. Moreover, it is most preferable that the carbon fiber is excellent in X-ray permeability. These reinforcing fibers are used in the form of strands, woven fabrics such as plain weave, satin weave, and twill weave. In addition, as the matrix resin, thermoplastic resins such as thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, polyimide resins, ABS resins, nylon resins, polyether ether ketone resins, polyolefin resins, etc. Resin can be used. Among these, a combination of carbon fiber and an epoxy resin or vinyl ester resin excellent in adhesiveness with the carbon fiber is preferable.
[0012]
The tensile strength and compressive strength of the FRP layer constituting the skin can be changed depending on the type, characteristics, and form of the reinforcing fibers, the type of the matrix resin, the thickness, and the like. For example, carbon fibers having various properties in terms of tensile strength, tensile elastic modulus, and the like are provided depending on the raw material fiber and the manufacturing method.
[0013]
The top plate of the present invention is suitable for medical X-ray equipment such as an X-ray imaging apparatus and a CT scanner (X-ray tomography apparatus).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, the top plate has a sandwich structure of a core 1 and a skin 2 provided so as to cover the core 1. The skin 2 has an upper skin 2a, a lower skin 2b, a right skin 2c, and a left skin 2d. However, the skin 2 can be provided only on the upper and lower surfaces of the core 1 instead of covering the core 1. Such a top plate can be formed by, for example, winding a reinforcing fiber prepreg around a core and heating and pressing to integrally form the core and skin, or by arranging reinforcing fiber prepregs on the upper and lower surfaces of the core. Can be manufactured. A separately molded skin and core may be bonded together.
[0015]
As shown in FIG. 2, the skin 2 has a plurality of, in this example, five FRP layers, both in the upper skin 2a and the lower skin 2b. That is, the upper skin 2a is composed of FRP layers 2a ₁ , 2a ₂ , 2a ₃ , 2a ₄ , 2a _{5 in} order from the core 1 side, and the lower skin 2b is composed of FRP layers 2b ₁ , 2b ₂ , in order from the core 1 side. It consists _{2b 3, 2b 4, 2b 5} . When the bending moment is applied to the top plate, the upper skin 2a, which is the tension side (convex side), has the FRP layer 2a ₁ positioned closest to the core ₁ as the FRP layer 2a positioned next to the FRP layer 2a _{1. The} FRP layer has a higher compressive strength than ₂ . The FRP layer 2a ₁ positioned closest to the core 1 is preferably an FRP layer having the highest compressive strength among the five FRP layers. On the other hand, the lower skin 2b which is on the compression side (concave side) when a bending moment is applied to the top plate, the FRP layer 2b ₁ located closest to the core 1 is replaced with the FRP layer located next to the FRP layer 2b _1. It has a high tensile strength FRP layer than 2b _2. The FRP layer 2b ₁ located closest to the core 1 is preferably an FRP layer having the highest tensile strength among the five FRP layers. In this way, in the present invention, when a bending moment is applied to the top plate, when the top plate is viewed as a whole, tensile stress is applied to the upper skin and compressive stress is applied to the lower skin. However, focusing only on the skin, on the inner layer side, paying attention to the fact that compressive stress is generated in the upper skin and tensile stress is generated in the lower skin. By placing the FRP layer with excellent compressive strength on the upper skin and the FRP layer with excellent tensile strength on the lower skin on the most core side, the core and skin can be made thinner. Therefore, it becomes possible to achieve high strength.
[0016]
In the above example, the upper skin that becomes the tension side when a bending moment is applied to the top plate, the FRP layer having the higher compressive strength than the FRP layer positioned next to the FRP layer positioned closest to the core side In addition, the lower skin that becomes the compression side when a bending moment is applied to the top plate is such that the FRP layer positioned closest to the core is the FRP layer having higher tensile strength than the FRP layer positioned next to the FRP layer. However, although the effect is reduced, only the upper skin can be configured as described above, or only the lower skin can be configured as described above.
[0017]
Examples and Comparative Examples
(Example)
A top plate having a sandwich structure of the core 1 and the skin 2 as shown in FIGS. 1 and 2 was manufactured. However, the upper skin and the lower skin were each composed of three FRP layers.
[0018]
A hard acrylic foam (shear elastic modulus: 27 MPa) having a thickness of 50 mm, a width of 500 mm, and a length of 1,300 mm was used for the core.
[0019]
Further, for the FRP layer, a carbon fiber satin fabric was used as the reinforcing fiber, and an epoxy resin and a vinyl ester resin were used as the matrix resin. However, the type of carbon fiber, the woven density, and the type of matrix resin were selected so that the tensile strength, compressive strength, and thickness of each FRP layer were as follows.
[0020]
FRP layer 2a ₁ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
FRP layer 2a ₂ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2a ₃ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2b ₁ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2b ₂ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
FRP layer 2b ₃ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
The breaking load of the obtained top plate was 1.4 tons. Here, the breaking load is an index of the bending strength of the top plate, and was measured as follows.
[0021]
That is, as shown in FIG. 3, the top plate 3 is fixed to the movable portion 5 attached to the main body 4 and is simply supported by the roller 6 provided on the main body 4. The movable portion 5 is provided so as to be movable in the front-rear direction (the left-right direction in the drawing), and the distance between the non-fixed end of the top plate 3 and the roller 6 is maximized during the test. Then, an equally distributed load is applied to the top plate 3, the load is gradually increased, and the load when the top plate 3 cannot be withstood for 1 minute and is broken is defined as a break load, and the value of the break load is used as an index of bending strength. To do.
(Comparative Example 1)
In embodiments, the FRP layer of high tensile strength in the FRP layer 2a ₁ to 2A region ₃ of the upper skin a tension side, FRP layer 2b ₁ ~2b ₃ of the lower skin is compressed side FRP layer with a high compressive strength In accordance with the design guidelines so far, each of the FRP layers has the following tensile strength, compressive strength, and thickness.
[0022]
FRP layer 2a ₁ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2a ₂ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2a ₃ :
Tensile strength 0.9 GPa, compressive strength 0.5 GPa, thickness 0.6 mm
FRP layer 2b ₁ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
FRP layer 2b ₂ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
FRP layer 2b ₃ :
Tensile strength 0.5 GPa, compressive strength 0.8 GPa, thickness 0.6 mm
The breaking load of the obtained top plate was 0.9 tons, which was significantly lower than that of the example.
(Comparative Example 2)
In Comparative Example 1, when the thickness of each FRP layer was changed to 0.8 mm so that the breaking load value of the top plate was substantially equal to that of the top plate obtained in the example, the aluminum equivalent representing the X-ray transmittance was It was about 20% lower than that of the example. Moreover, the increase in the thickness of the FRP layer increased the material cost of the layer by about 30% compared to the example.
[0023]
【The invention's effect】
In the top plate having a sandwich structure of a core and an FRP skin, the present invention provides a high compression strength FRP layer on the skin on the tension side when a bending moment is applied, or when a bending moment is applied. By placing a high tensile strength FRP layer on the skin on the compression side, it is extremely effective to increase the strength of the top plate for medical devices, as is clear from the comparison between the example and the comparative example. Will be able to achieve. Moreover, since it is not necessary to make all the FRP layers have high specifications, material costs and the like can be reduced, and manufacturing costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a top plate according to an embodiment of the present invention.
FIG. 2 is a model diagram showing a longitudinal section of the top plate shown in FIG.
FIG. 3 is a model diagram of a strength test method for a top board.
[Explanation of symbols]
1: Core 2: Skin 2a: Upper skin 2b: Lower skin 2c: Right skin 2d: Left skin 2a _{1 to} 2a ₅ : FRP layer 2b _{1 to} 2b ₅ : FRP layer 3: Top plate 4: Body 5: Movable part 6: Roller

Claims (8)

It has a sandwich structure of a core and a skin made of FRP. The skin includes a plurality of FRP layers, and the skin that becomes the tension side when a bending moment is applied is the FRP layer located on the most core side. A medical device top plate in which an FRP layer having a higher compressive strength than the FRP layer positioned next to the FRP layer is disposed. The medical device top plate according to claim 1, wherein the FRP layer located closest to the core is the FRP layer having the highest compressive strength among the plurality of FRP layers. It has a sandwich structure of a core and an FRP skin, and the skin includes a plurality of FRP layers, and the skin that becomes the compression side when a bending moment acts on the FRP layer located closest to the core side. A top plate for a medical device in which an FRP layer having a higher tensile strength than the FRP layer positioned next to the FRP layer is disposed. The medical device top plate according to claim 3, wherein the FRP layer positioned closest to the core is an FRP layer having the highest tensile strength among the plurality of FRP layers. It has a sandwich structure of the core and the FRP skin, and the skin includes a plurality of FRP layers, and the skin that becomes the tension side when the bending moment is applied has the FRP layer positioned closest to the core side. An FRP layer having a compressive strength higher than that of the FRP layer positioned next to the FRP layer is arranged, and the skin that becomes the compression side when bending stress is applied in the length direction has the FRP layer positioned closest to the core side. A top plate for a medical device in which an FRP layer having a higher tensile strength than the FRP layer positioned next to the FRP layer is disposed. The FRP layer located on the most core side of the skin that becomes the tension side when the bending moment acts is the FRP layer having the highest compressive strength among the plurality of FRP layers. The medical device top plate according to claim 5, wherein the FRP layer located closest to the core of the skin is a FRP layer having the highest tensile strength among the plurality of FRP layers. The medical according to any one of claims 1 to 6, wherein the core is a rigid plastic foam such as polyurethane foam, polystyrene foam, polyvinyl chloride foam, acrylic foam, polymethacrylimide foam, cellulose acetate foam, epoxy foam, and phenol foam. Equipment top plate. The medical device top plate according to claim 1, wherein the plurality of FRP layers include a CFRP layer.

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