JP7406346B2 - Composite of sheet material and base material and manufacturing method thereof - Google Patents

Description

The present invention relates to a composite formed by joining a breathable sheet material to a synthetic resin base material by ultrasonic welding, and a method for manufacturing the same. The composite includes a chair component, in which the substrate can be identified as, for example, a frame material.

Ultrasonic welding is used in various fields. One of the ways in which ultrasonic welding is used is to weld cloth materials to synthetic resin base materials. An example thereof is disclosed in Patent Document 1.

That is, in Patent Document 1, a large number of protrusions are formed at the tip of a horn serving as a welding tool, and the large number of protrusions increases the surface area of the friction surface and increases the meltability of the base material. ) is deeply penetrated (embedded) into the base material and integrated.

In Patent Document 1, in the welding process, the part of the cloth material that is pressed by the horn enters the base material in a thinly crushed state, and the molten synthetic resin gets entangled with the thinly crushed cloth material. When the molten synthetic resin hardens, the cloth material and the base material become integrated. Therefore, the cloth material is firmly joined to the base material at the location where the tip end surface of the horn hits.

Japanese Patent Application Publication No. 2007-181963

Now, in Patent Document 1, since the base material is melted and the molten resin is entangled with the cloth material, it is necessary to enter the horn into the base material to melt the base material. The pressing action of the horn deforms it into a U-shaped cross section. That is, after welding, the welded portion of the cloth material has a bottom portion where the tip end surface of the horn overlapped, and a cylindrical portion where the outer peripheral surface of the horn overlapped.

As mentioned above, the bottom part of the welded part of the fabric where the tip of the horn overlapped is firmly fixed to the base material, but since the horn penetrates into the base material, the outer periphery of the horn There has been a problem in that the phenomenon of edge breakage in which the fibers of the cloth material are cut by the edge portions is likely to occur. In addition, when the horn enters the base material, the cylindrical portion of the welded portion of the cloth material tends to form a thin burr-like shape, so if the cloth material is pulled after welding, it may easily tear at the cylindrical portion.

In other words, in the past, not only did the tensile strength of the fabric material decrease due to edge breakage, but also the cylindrical part of the welded part became burred, making it easy for stress to concentrate, so sufficient fixing strength could not be maintained. There were times when I couldn't do it. In the end, it can be said that in the past, the effect of forming a large number of protrusions on the tip surface of the horn could not be fully utilized.

One possible solution to this problem is to manufacture the sheet material from a strong material (fiber) that will not cause edge breakage even under the intense friction caused by the horn, but this solution requires the use of expensive materials. This cannot be said to be a realistic solution, as there are problems of increased costs and the possibility that it is difficult to obtain strong materials that do not cause edge breakage. Therefore, it can be said that there is a need for a welding technique that uses common fabric materials and has high bonding strength.

The present invention is intended to meet such demands.

The present invention has many aspects, and typical configurations thereof are specified in each claim.

Among these, the invention of claim 1 relates to a composite body in which a sheet material is welded to a base material,
"A breathable sheet material and a synthetic resin base material overlapping the same are joined to each other at at least one welded portion, and the sheet material and the base material are integrated at the welded portion. The configuration is
The welded portion includes a main welded portion that is entirely inserted into the base material, and a sub-welded portion that is formed in a ring shape surrounding the main welded portion and is joined to the surface of the base material . The main welded part and the cylindrical welded part of the sheet material are comprised of a cylindrical welded part that extends into the inside of the base material continuously from the outer periphery of the main welded part and the inner periphery of the sub-welded part. A recess surrounded by
and the main welding part is formed to have an uneven cross-sectional shape,
The cylindrical weld part is formed into a tapered part whose diameter increases from the main weld part toward the sub-weld part .
The structure is as follows.

The invention of claim 2 is applied to a composite body constituting a chair,
" The base material is a frame material constituting a chair and has a longitudinal direction, and the frame material and the sheet material are mutually connected to each other by a large number of welded parts scattered in the longitudinal direction of the frame material. It is joined .”
The structure is as follows.

The invention of claim 3 relates to the method for producing the composite described in claim 1 or 2 ,
" It has a pre-process of stacking the sheet material on the base material, and a welding process of pressing the sheet material and the base material while vibrating a horn, and in the welding process, the sheet material is bonded by the horn. In the configuration that is crushed and integrated with the base material to become the welded part,
The tip of the horn is formed with a main pressing part that is tapered and has a trapezoidal cross section, and a sub-pressing part that spreads out in an annular shape from the base end of the main pressing part, and the tip surface of the main pressing part Many protrusions are formed on the
In the welding step, the main pressing force on the horn is achieved by advancing the horn until the main pressing part enters the inside of the base material and the sub-pressing part hits the surface of the base material through the sheet. The main welded part is formed by the main welded part, and the molten synthetic resin generated at the main welded part is swept away toward the sheet material to form the cylindrical welded part and the sub-welded part . "
The structure is as follows.

The invention of claim 4 relates to the method for manufacturing the chair composite body described in claim 2 , and in claim 3,
"The base material is a frame material constituting a chair and has a longitudinal direction, and a unit welding operation to form one welded part is repeatedly performed along the longitudinal direction of the frame material."
The structure is as follows.

Examples of composite bodies that are chair members include a mesh-type backrest, a mesh-type seat, and a mesh-type headrest or shoulder rest. Alternatively, the present invention can also be applied to welding the skin material to the inner shell in a cushion type backrest, etc., in which a cushion material is layered on a resin inner shell and the cushion material is covered with a skin material such as cloth.

In the present invention, the welded portion of the composite body has a main welded portion, a sub-welded portion, and a cylindrical welded portion. A feature of the present invention is that, first, the area of the welded portion is greatly expanded compared to the conventional one, thereby suppressing the concentration of external force in a narrow area and significantly improving the strength against tension.

In addition, when the sheet material is pulled, the external force first acts on the sub-welded part, but in the present invention, the sub-welded part is stepped up to the surface side of the sheet material so as to overlap with the surface side of the base material. Since the degree of compression is small, there is no burr formation and no edge breakage of the fibers at the sub-welds. Therefore, it has high strength (tensile strength, shear strength) that is difficult to break. keeping.

At the main weld, the sheet material is strongly pressed and firmly bonded to the base material, but the sub-weld acts as a buffer, preventing stress from concentrating on the outer periphery of the main weld. Or it can be significantly suppressed. Therefore, even if edge breakage occurs at the outer peripheral edge of the main weld, high fixing strength can be maintained as a whole of the weld.

Furthermore, regarding edge cuts, in the past, the sheet material was largely stretched by a horn, creating a state similar to deep drawing, making it easy for edge cuts to occur in the sheet material, but the present invention In this case, since the sub-welded part is formed to be stepped up from the main welded part, the amount of elongation of the sheet material is smaller than that of the conventional method, and therefore edge breakage of the sheet material can be greatly suppressed. In this respect as well, the fixing strength of the welded part can be improved.

Furthermore, when the cylindrical welded portion is formed into a tapered shape as in the present invention , the edge portion of the horn has an obtuse angle, so that stress concentration on the fibers constituting the sheet material can be suppressed during the welding process. As a result, edge breakage of the sheet material can be prevented or significantly suppressed. Therefore, the fixing strength of the welded portion can be further improved.

When a horn having a large number of protrusions formed on its tip surface is used, the cross section of the main welded portion can be formed into an uneven shape, as in the present invention . As a result, the surface area of the main weld can be significantly increased, which not only improves the bonding strength of the main weld, but also increases the amount of base material melted at the main weld, allowing the molten synthetic resin to It is possible to ensure that the water is swept away from the main weld part toward the cylindrical weld part and the sub-weld part. Therefore, the formation of the cylindrical welded portion and the sub-welded portion can be ensured, and the joint strength can be ensured to be improved.

Now, regarding chairs, for example, centering on rotating chairs that are often used for office purposes, the backrest and seat are made of a frame material covered with mesh material, which is an example of sheet material. This type of backrest and seat has the advantage of excellent breathability and cushioning properties. In some cases, mesh material is welded to the frame material, but it is difficult to say that it is widely used due to concerns about strength.

In this regard, when applied to a composite body constituting a chair as claimed in claims 2 and 4 of the present application, the mesh material can be firmly fixed to the frame material, so the structure of the backrest, seat, etc. can be simplified and costs can be reduced. Can be configured as a mesh type. Furthermore, since the fixing strength is high, it is possible to develop the tension state of the mesh material in various ways, and therefore there is an advantage that the freedom of design can be improved.

Figures illustrating an embodiment applied to a chair; (A) is a front view of the chair, (B) is a sectional view taken along line BB in (A), and (C) is a rear view taken along line CC in (B). be. It is a figure which shows the horn used for embodiment, (A) is a front view seen from the direction orthogonal to an axis, (B) is a perspective view seen from below. FIG. 3 is a longitudinal sectional front view showing a welding process. It is a sectional view of the main part after welding. FIG. 7 is a longitudinal sectional front view of the second embodiment. FIG. 7 is a longitudinal sectional front view of the third embodiment.

(1). Overview of Chair Next, embodiments of the present invention will be described based on the drawings. In this embodiment, it is applied to the backrest of a chair. That is, the backrest of a chair is used as an example of a composite body. As can be understood from FIG. 1(A), the chair is a rocking rotating chair that is often used for office use, and includes a leg device 1 equipped with casters, a seat 2 supported by the leg device 1, and a backrest 3. ing.

The backrest 3 has a structure in which a mesh material 5 is stretched over a frame material 4 having front and rear openings, and the load when a seated person places his or her body on the backrest 3 is supported by the mesh material 5. The frame material 4 is an example of the base material described in the claims, and is manufactured by injection molding using a synthetic resin such as nylon resin. The mesh material 5 is an example of a sheet material described in the claims, and has breathability that allows molten resin to enter.For example, a knitted fabric using strong synthetic resin yarn is used. Woven fabrics and pile fabrics can also be used. Moreover, the mesh material 5 may have a laminated structure.

In FIG. 1, (B) is a cross-sectional view taken along the line BB in (A), and as shown in (B), in this embodiment, the outer peripheral part 5a of the mesh material 5 is wrapped around the frame material 4 from the outside. The outer circumference 5a of the mesh material 5 is welded to the rear surface of the frame material 4 to form a welded portion 6. The outer peripheral part 5a of the mesh material 5 is covered from behind by a cover 7. In FIG. 1, (C) is a rear view taken along the line CC of (A) with the cover 7 omitted. 4 in the longitudinal direction).

The frame material 4 has vertical and longitudinal side members, and left and right longitudinal upper and lower members, and has an almost rectangular shape as a whole, but the entire circumference of the mesh material 5 is directly welded to each member. Alternatively, for example, it is also possible to directly weld the outer circumference 5s to the side member and the upper member, and attach it to the lower member via another member whose edge is welded. .

A horn 8, only the tip of which is shown in FIG. 2, is used to weld the mesh material 5. The horn 8 is circular (round bar-shaped) and includes a main pressing part 10 having a large number of protrusions 9 on its tip surface, and a ring-shaped sub-pressing part 11 stepped down from the main pressing part 10. The outer circumferential surface 10a of the main pressing section 10 is a tapered surface whose diameter increases toward the sub-pressing section 11. Therefore, the main pressing portion 10 has a trapezoidal cross section with a tapered end. Each protrusion 9 has a quadrangular pyramid shape and is arranged in alignment in orthogonal directions. In other words, they are arranged in a grid.

In addition, each protrusion 9 can be formed into a slightly flat surface without sharpening the tip (formed into a truncated pyramid shape), or formed into a pyramid shape with a rounded tip. It is. Further, although the horn 8 in the embodiment is circular, it can also be formed into a polygonal shape such as a quadrangle or a hexagon.

(2).Welding process In the welding process, the frame material 4 is held by an anvil (not shown, a jig) so as not to be displaced, and the edge 5a of the mesh material 5 is overlapped with the frame material 4, and the horn 8 The mesh material 5 is welded to the frame material 4 by pressing it against the mesh material 5 and the frame material 4 by a drive device (not shown) while vibrating in the axial direction thereof. The welding location may be moved by moving the anvil or by moving the position of the horn 8.

Welding of the mesh material 5 is performed by the mechanism shown in FIG. That is, by pressing the horn 8, the mesh material 5 is first partially crushed by the main pressing part 10 as shown in (A), and then the main pressing part 10 is crushed as shown in (B) and (C). The main pressing part 9 enters (sinks into) the frame material 4 together with the crushed mesh material 5, and the sub-pressing part 11 of the horn 8 enters the mesh material 5.

Then, when the main pressing part 10 enters the frame material 4, the surface part of the frame material 4 melts, and a part of the molten synthetic resin gets entangled with the crushed mesh material 5, while a part of the molten synthetic resin A part of it overflows from the area between the main pressing part 10 and the frame material 4, is pushed out, flows along the tapered surface 10a toward the sub-pressing part 11, and finally reaches the point shown in FIG. As shown in FIG. 3(C), the mesh material 5 is entangled with the mesh material 5 at the sub-pressing portion 11 and integrated.

Therefore, the welded part 6 formed by the resin solidifying after the horn 8 retreats overlaps the main welded part 12 that has entered the thick part of the frame material 4 and the surface of the frame material 4, as shown in FIG. It is composed of a sub-welded part 13 that is stepped up and a tapered cylindrical welded part 14 that connects the two, and the cylindrical welded part 14 also enters into the thick part of the frame material 4. Therefore, a recessed part 15 into which the main welded part 12 and the cylindrical welded part 14 enter is formed in the frame material 4, and a region surrounded by the main welded part 12, the cylindrical welded part 14, and the sub-welded part 12. has a recess of 16.

From this, the main pressing part 10 and the sub-pressing part 11 in the horn 8 are set at such a height that the main pressing part 10 fully enters the frame material 4 and the sub-pressing part 11 enters only the mesh material 5. The relationship is set. Generally, it can be said that the height difference H1 between the main pressing part 10 and the sub-pressing part 11 may be approximately the same as the thickness T of the mesh material 5. Although the sub-pressing part 11 does not enter the frame material 4, it is possible that the sub-welding part 13 partially enters into the thick part of the frame material 4.

The area of the welded part 6 of this embodiment is larger by the width of the sub-pressing part 11 compared to the conventional example in which the horn 8 is simply straight. Further, since the cylindrical welded portion 14 has a tapered shape whose diameter increases toward the surface side, the area of the cylindrical welded portion 14 is also larger than that of the conventional case. As the area of the welded portion 6 is increased in this way, the resistance to external force is significantly increased.

Further, since the sub-pressing part 11 of the horn 8 does not enter the frame material 4, the fibers of the mesh material 5 are not cut by the outer peripheral edge (edge part) of the sub-pressing part 11, and the sub-welded part 13 It is strongly connected to the outside parts. Therefore, even if the user leans against the backrest 4 and an external force is applied to the mesh material 5 to pull or tear it off, the mesh material 5 will tear along the outer periphery of the sub-welded part 13. does not occur.

On the other hand, due to the large number of protrusions 9 formed at the tip of the main pressing part 10 of the horn 8, the bonding area between the main welding part 12 and the frame material 4 is very large, so the main welding Although the part 12 is firmly fixed to the frame material 4, the sub-welded part 13 acts as a buffer and no large external force is applied to the main welded part 12 or the cylindrical welded part 14. Even if the phenomenon of edge breakage occurs in the cylindrical welded part 14, the welded part 6 as a whole maintains high fixing strength.

Furthermore, since the mesh material 5 is crushed by the sub-pressing section 11, the extrusion dimension of the mesh material 5 by the main pressing section 10 is smaller than before (the height dimension H2 of the cylindrical welded section 14 is smaller than before). are also smaller). Therefore, the tensile force acting on the mesh material 5 as the main pressing part 10 is pressed is smaller than in the past, and as a result, the phenomenon of edge breakage is less likely to occur.

Furthermore, if the outer circumferential surface 10a of the main pressing part 10 is formed into a tapered surface as in the embodiment, stress concentration on the narrow line-shaped portion of the mesh material 5 can be greatly suppressed, thereby further reducing the phenomenon of edge breakage. Can be prevented accurately.

After all, in this embodiment, the fibers are crushed without being cut and the resin is entangled at the welded portion 6, so the welded portion 6 as a whole is strong, and the main welded portion 12 is Since it is firmly fixed to the frame material 4, it fully enjoys the effect of forming a large number of protrusions 9 on the tip surface of the main pressing part 10, and exhibits high resistance to external forces such as pulling and rolling. .

(3).Other Embodiments In a second embodiment shown in FIG. 5, the sub-pressing part 11 of the horn 8 is formed into a concave surface recessed upward. When formed in this way, the sub-welded part 13 becomes thicker, so that the reinforcing effect and buffering effect of the sub-welded part 13 can be further improved.

In the third embodiment shown in FIG. 6, the sub-pressing part 11 is set as an inclined surface whose diameter increases upward. In this case, since the thickness of the sub-welded part 13 increases toward the outer periphery, the melted resin can escape easily. Therefore, it can be said that the entanglement between the mesh material 5 and the resin can be improved.

The present invention can be embodied in various other ways. For example, in the case of a horn, the protrusion may be formed into a circular shape or may be formed into a convex surface that is gently curved as a whole. It is also possible to form a tapered surface that is smoothly continuous from the outer periphery of the main pressing part 10 to the outer periphery of the sub-pressing part.

Regarding the composite body to which the present invention is applied, it is not limited to chair members, but can be widely applied to various articles such as other furniture and miscellaneous goods. The sheet material is not limited to fabrics such as mesh materials, but may also include nonwoven fabrics and papers. Note that the sheet material does not need to be made of synthetic resin, as long as it has air permeability that allows the molten synthetic resin to enter the voids. Therefore, sheet materials made of cellulose-based natural materials or metal materials can also be used.

The present invention can be embodied in ultrasonic welding technology. Therefore, it can be used industrially.

3 Chair backrest as an example of a composite 4 Frame material as an example of a base material 5 Mesh material as an example of a sheet material 6 Welded part 8 Horn 9 Projection 10 Main pressing part of the horn 10a Outer peripheral surface of the main pressing part 11 Horn Sub-pressing part 12 Main welding part 13 Sub-welding part 14 Cylindrical welding part
15 Recessed part
16 Recess

Claims (4)

A configuration in which a breathable sheet material and a synthetic resin base material overlapping the same are joined to each other at at least one welded part, and the sheet material and the base material are integrated at the welded part. And,
The welded portion includes a main welded portion that is entirely inserted into the base material, and a sub-welded portion that is formed in a ring shape surrounding the main welded portion and is joined to the surface of the base material . The main welded part and the cylindrical welded part of the sheet material are comprised of a cylindrical welded part that extends into the inside of the base material continuously from the outer periphery of the main welded part and the inner periphery of the sub-welded part. A recess surrounded by
and the main welding part is formed to have an uneven cross-sectional shape,
The cylindrical weld part is formed in a tapered part whose diameter increases from the main weld part toward the sub-weld part.
A composite of sheet material and base material. The base material is a frame material constituting a chair and has a longitudinal direction, and the frame material and the sheet material are connected to each other by a large number of welded parts scattered in the longitudinal direction of the frame material. are combined,
A composite for a chair, which is a composite of the sheet material according to claim 1 and a base material. A method for producing a composite according to claim 1 or 2 , comprising:
The method includes a pre-process of stacking the sheet material on a base material, and a welding process of pressing the sheet material and the base material while vibrating a horn, and in the welding process, the sheet material is pressed by the horn. In the configuration that becomes the welded part by being crushed and integrated with the base material,
The tip of the horn is formed with a main pressing part that is tapered and has a trapezoidal cross section, and a sub-pressing part that spreads out in an annular shape from the base end of the main pressing part, and the tip surface of the main pressing part Many protrusions are formed on the
In the welding step, the main pressing force on the horn is achieved by advancing the horn until the main pressing part enters the inside of the base material and the sub-pressing part hits the surface of the base material through the sheet. The main welded part is formed by the main welded part, and the molten synthetic resin generated at the main welded part is swept away toward the sheet material to form the cylindrical welded part and the sub-welded part . and
A method for manufacturing a composite consisting of a sheet material and a base material. The base material is a frame material constituting a chair and has a longitudinal direction, and a unit welding operation to form one welded part is repeatedly performed along the longitudinal direction of the frame material,
A method for producing a composite comprising the sheet material according to claim 3 and a base material.

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