SEAT AND METHOD FOR MANUFACTURING A SEAT

Abstract: A seat including a one piece moulded plastic part defining a seat bottom portion and a seat back portion in which the plastic part (1) is formed by blow moulding. The seat also has a reinforcement frame (2) received in formations moulded along a peripheral edge of the plastic part (1). The seat is preferably manufactured by placing a reinforcement frame (2) in a mould (A, B) and then blow moulding within the mould a one piece plastic part (1) defining a seat bottom portion and a seat back portion, thereby producing in a single operation a seat in which the frame is at least partially embedded in a peripheral edge of the plastic part.

Description: Title: "SEAT AND METHOD FOR MANUFACTURING A SEAT" The present invention refers to a seat and a method of manufacturing a seat, that is to say, seats in general and particularly seats suitable for use in automative vehicles such as buses and coaches. The invention does, however, apply to other types of seats, such as those intended for domestic use and the like. Many types of seats are known. They are made with many different types of structures and manufactured using many different types of materials, normally being developed with a view to greater practicality, low cost and acceptable mechan¬ ical strength allied with the lowest possible weight. In order to achieve the above objectives, the pres¬ ent invention provides a new seat including a one piece moulded plastic part defining a seat bottom portion and a seat back portion, in which such plastic part is formed by blow moulding, the seat further comprising a reinforcement frame received in formations moulded along a peripheral edge of the plastic part. Preferably, the formations are in the form of reentrances or claws. Equally, it is preferred that the reinforcement frame comprises a tubular peripheral structure. The fixing of the frame to the plastic part is pref- erably effected during moulding, the reentrances or claws be¬ ing moulded directly over the frame so as to surround approximately three quarters of the cross section of the tubu- lar structure of the frame. The peripheral edge of the plastic part may have cut-away areas so as to leave parts of the frame exposed which serve as hand grips for the passenger of a vehicle in which the seat is mounted. The present invention also refers to a method for manufacturing such a seat. The method comprises placing a re¬ inforcement frame in a mould and then blow moulding within the mould a one piece plastic part defining a seat bottom portion and a seat back portion, thereby producing a seat in which the frame is at least partially embedded in a peripheral edge of the plastic part. This method has been developed exclusively for the use of blow moulding techniques which are relatively recent in the plastic transformation field. In a preferred embodiment, the reinforcement frame is maintained in position in the mould by magnetic attraction produced by magnets associated with the mould. The use of such a method of manufacture in which the plastic part surrounds almost completely the cross section of the frame, eliminates the problem of cracking or splitting of the plastic part in view of the fact that there are no stress concentrations. The invention will be better understood by the fol- lowing description given by way of example and made with ref¬ erence to the accompanying drawings, in which: Figure 1 is a side elevation of a seat in accordance with the present invention; Figure 2 is a front elevation of the same seat; Figure 3 is a double seat that may be manufactured in accordance with the invention; Figure 4 is a detail of the seat with the plastic part and the frame, the plastic part being cut away longitudinally to show the fitment between its edge and the frame; Figure 5 is a sectional detail of part of the edge of the seat, showing the connection between the plastic part and the frame; Figure 6 is a schematic showing of a mould suitable for moulding the plastic part directly onto the frame. As can be seen from Figure 1, the seat is basically comprised of a one piece blow moulded plastic part 1 having a seat bottom portion and a seat back portion, the peripheral edge of such part receiving therein a metallic reinforcement frame 2. A connecting part 3, shown in more detail in Figure 4, joins two parallel horizontal sections of that part of the frame that corresponds to the seat bottom portion of the seat. Connecting part 3 serves for mounting the seat on feet or other base structure (not shown). Plastic part 1 is moulded as a single part and has a peripheral edge provided with formations in the form of reentrances or claws which receive and at least partially sur- round, for example about three quarters of the cross section of the tube that forms the peripheral structure of the frame 2. Figure 5 shows a detail of the preferred fitment between frame 2 and plastic part 1, showing how the tubular peripheral member of the frame is tightly received in a correspondingly shaped longitudinal cavity or reentrance in the edge of the plastic part. Figure 2 shows how the plastic part 1 may have one or more cut-away areas 5 so as to expose a section of the tube of the frame and thus to define a hand grip. Figure 3 shows a one piece moulding of a double seat. Naturally, longer bench type seats with any suitable number of seating places may be produced. The seat side of plastic part 1 is anatomically shaped to ensure the comfort of the user.#.illO#It should be noted that in general the frame 2 may be made from any suit¬ ably rigid and strong material to provide the support and re¬ inforcement necessary but that a metallic frame would normally be preferred. In particular, when the seat is manufactured by the preferred process of this invention, it should be made of a magnetic material as will be understood from the following description of the method. Figure 6 is a schematic showing of a blow mould for producing the seat of the present invention. The mould com¬ prises two mould halves A and B, no further description of the conventional features of the mould being given since they are nor relevant to the present invention. In order to produce the seat, the previously manufactured reinforcement frame 2 is placed within part B of the mould and maintained in position due to the magnetic attraction produced by a series of magnets 6 (also shown schematically) accociated with mould half B. The plastic blow moulding parison is then introduced into the mould which is then closed and blow moulding is carried out. The resulting product is thus obtained with the plastic part 1 of the seat moulded directly over the frame 2 in a single op¬ eration, ensuring that the frame is effectively embedded in the moulded plastic part 1 with fitments as shown in Figures 4 and 5. Finally, it will be appreciated that, although the above method is highly preferred, the plastic portion could be moulded separately with its specially formed peripheral edge and only after that the frame could be force fitted into the reentrances formed therein. Equally, the specific shape of the reentrances or claws is not limited to that shown in Figures 4 and 5, it being clear that other sectional shapes would be suitable provided that there are negative surfaces that pre¬ vent the separation of the plastic part from the frame during use.

Claims: CLAIMS 1. Seat including a one piece moulded plastic part defining a seat bottom portion and a seat back portion, characterised in that said part (1) is formed by blow moulding and in that said seat further comprises a reinforcement frame (2) received in formations moulded along a peripheral edge of said plastic part (1). 2. Seat according to claim 1, characterised in that the said formations are reentrances or claws. 3. Seat according to claim 1 or 2, characterised in that said reinforcement frame (2) comprises a tubular periph¬ eral structure. 4. Seat according to claim 2, characterised in that said reentrances or claws surround approximately three quar- ters of the cross section of the tubular structure of said frame (2). 5. Seat according to claim 1, 2, 3 or 4, characterised in that said peripheral edge of said plastic part (1) has cut-away areas (5), leaving parts of said frame exposed in said areas. 6. Method for manufacturing a seat such as claimed in any one of the preceding claims, characterised by placing a reinforcement frame in a mould and then blow moulding within the mould a one piece plastic part defining a seat bottom por- tion and a seat back portion, thereby producing a seat in which said frame is at least partially embedded in a periph¬ eral edge of said plastic part. 7. Method for manufacturing a seat such as claimed in claim 6, characterised in that said reinforcement frame is maintained in position in said mould by magnetic attraction. 8. Method for manufacturing a seat such as claimed in claim 7, characterised in that said magnetic attraction is produced by magnets associated with said mould.

Inventors: GONZALES FERNANDEZ JOSE, GONZALES FERNANDEZ, JOSE
Applicants: DAIMLER BENZ BRASIL, MERCEDES-BENZ DO BRASIL S.A.
Application year: 1991
Main classification: B29C49
IPC codes: A47C5, B29C49