GB1595572A

GB1595572A - Blow-moulded chair seats

Info

Publication number: GB1595572A
Application number: GB8458/78A
Authority: GB
Original assignee: VS SCHULMOEBEL GmbH
Current assignee: VS SCHULMOEBEL GmbH
Priority date: 1977-03-04
Filing date: 1978-03-03
Publication date: 1981-08-12
Also published as: FR2382217A1; IT7820861A0; IT1093148B; ATA140178A; DE2709542A1; AT367993B; DE2709542C2

Description

(54) IMPROVEMENTS IN BLOW-MOULDED CHAIR SEATS (71) We. VS-SCHULMÖBEL VER WALTUNGS-GMBH. a German Companv of Hochhaeuser Strasse 8. 6972 Tauberbi schofsheim, Federal Republic of germany.

do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to seats for stackable chairs as described for example in published German specification (Offenle gungsschrift) No. 2 353 341.

In accordance with one aspect of the invention a chair seat comprising a hollow shell which has been blow-moulded and whose topside forming the seat face has ventilation holes which have been formed during the blow-moulding process.

In accordance with another aspect of the invention, a stackable chair has a metal frame which comprises two runners and two rearwardly inclined lateral uprights which are attached to the runners and between which a seat support is mounted. the chair having a backrest attached to the upper ends of the frame uprights and a seat on the seat support, the seat comprising a hollow shell which has been blow-moulded and having on its topside forming the seat face, ventila tion holes which have been formed during the blow-moulding process.

The invention includes a method for blow-moulding a chair seat in the form of a hollow shell with ventilation holes in its topside forming the seat face. in which, 'during or after the blowing operation and whilst the softened blow-moulded shell is still in the blow-mould into the topside of the seat until through holes are formed.

The invention also includes blow moulding apparatus for making a chair seat in the form of a hollow shell with ventilating holes in its topside forming the seat face. in which a blow-mould member for moulding the topside of the seat has numerous pins which can be introduced into the mould interior through respective apertures in the blow-mould member during or after the blowing operation in order to pierce the topside of the seat.

It is thus possible to provide the ventilation holes immediately and concomittantly in a simple manner and without additional operating processes or additional heating or clamping of the seat, although per se mouldings of this kind are not possible by a blow-moulding method.

The invention is further described, by way of example. with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a chair having a chair seat in accordance with the invention; Figure 2 is a section through the seat along the line ll-ll in Figure 1; Figure 3 is a fragmentary plan view of the seat; Figure 4 is an end view of the seat when removed from the seat support frame; Figure 5 is a diagrammatic detailed sectional representation of a blow-mould for the production of the seat; Figure 6 is a rear view of the backrest of the chair; Figure 7 is a vertical section through the backrest: Figure 8 is a partially sectioned end view of the backrest: and Figure 9 is a horizontal detailed section through the backrest.

The chair 11 in Figures 1 to 3 includes a frame 12 of flat oval steel tubing whose cross-section comprises two semi-circular arcs joined by straight lateral walls.

A base frame 13 forms part of the frame 12 and comprises two lateral runners 14, which extend in the longitudinal direction of the chair. and a rear crosspiece 15 which joins the two runners 14 together. The U-shaped base frame is bent from one piece and the U-shape is open towards the front.

The front ends are closed by closure members 16 of plastics material which are slipped over the free ends of the runners 14 and their lower supporting faces 17 serve as slides to protect the floor from being scratched. Supporting members 18 are situated in the region of the rear corners.

The frame 12 also includes two lateral uprights 19 which are substantially straight but backwardly inclined and whose lower ends are attached at the outside to the central region (a little in front of the middle) of the runners 14 bv a welds 2() to enable the base frame of another like chair stacked on the illustrated chair to pass between the uprights 19.

At seat level the uprights 19 are joined together by means of a U-shaped seat supporting frame 21 of flat oval tubing. the U-shape being closed at the front and open at the rear. The seat supporting frame passes around the outside of the seat 22 and is inserted between the uprights 19 by means of a weld 23 in such a manner that the seat of one chair passes between the supports of an identical chair below during stacking.

The upper end portions of the uprights 19 are joined together by a backrest 31 which also serves to close the upper ends 34 of the uprights.

The seat 22 is a hollow member of plastics material which is substantially closed on all sides and is produced by means of a blowmoulding process. It has a topside 24 serving as a seat face and an underside 25 which is provided with cruciform depressions 26, which reinforce the underside of the seat, and a ventilation opening 52 at the lowest point. In the region which is enclosed by the seat supporting frame 21, the periphery of the seat has a folded-in-like recess 27 whose shape is adapted to the outer structural form of the seat supporting frame 21 and in the present example forms a groove. The rounded upper side or step of the recess or groove overlaps the seat supporting frame 21 so that a very uniform transition and moreover a good grip result.

The topside 24 of the seat has many ventilation holes Sü (Figures 2 and 3) of relatively small diameter. Thev are distributed over the seat face and pass through the topside 24 of the hollow seat mould member. Their rims are the rounded at their upper end (see Figure 5).

The recess 27 extends about the front side and the lateral edges of the seat 22 but terminates short of the rear side of the seat so that a projection 55 is formed in this region and covers the open ends of the hollow seat-supporting frame 21. Two for wardly directed projections 29 are provided in the region of the recess 27 at the front side of the seat and project into holes 58 in the seat supporting frame. The seat has two holes 32, aligned with each other, in the rear part of the sides, through which holes a tubular locking bar 35 is guided. The ends of the locking bar 35 thereby project from these holes by a small amount.The attachment of the seat 22 takes place in such a manner that the seat can be slipped in from behind and above between the uprights 19 so that the front projections 29 come to be located approximately in front of the corresponding holes 58 in the seat supporting frame 21. Then, prior to the fitting of the back support 31, the two uprights 19 are splayed outwards away from each other so that the limbs of the U-shaped seat supporting frame 21, which are welded onto the two uprights 19, are also somewhat splayed out and the laterally projecting ends of the locking bar 35 are brought into confrontation with holes 36 at the inside of the seat supporting frame 21. The supports are then released so that the locking bar ends enter these holes and secure the seat. The backrest 31 is then slipped over the uprights 19.

The seat is thus permanently secured in a most simple manner without separate attaching parts having been required.

The holes 5) in the seat topside 24 are moulded in a novel production method during the blow-moulding of the seat (Figure 5). The blow-moulding, using a blowmould 6ü is effected initially in a conventional manner. However. in the mould surface. which moulds the seat topside 24, an aperture 61 is provided for each ventilation hole 5(). Pins 62 can penetrate the apertures 61 and are attached to a common plate 67 which in Figure 5 is disposed so as to be vertically displaceable. The pins 62 each have a larger diameter shank 63 matching the diameter of the apertures 61, and a smaller diameter tip 64 which forms the ventilation holes 5). A rounded fillet 65 is provided at the junction between the two diameters but a conical shoulder will alternatively be provided.

After the actual blowing operation is carried out and the topside 24 is in abutment with the corresponding mould surface. the plate 67 having been previously moved upwards so that the pins of this plate lie outside the mould interior. is moved downwards so that it adopts the position shown in Figure 5.In so doing the shanks 63 occupy the apertures 61 adjoining the mould in interior The pins 62 press through the material of the seat. which is still soft due to its having been heated, and are constructed to be so long that the pierce the seat topside 24. The fillets 65 mould the rounded part at the openings of the ventilation holes. Vhe lengths of the shanks 63 of the pins are adapted so that the locating of the fillets 65 follow the shape of the seat topside.

As can be seen from Figures 1 and 6 to 9 the backrest 31 is also a hollow member of plastics material which is manufactured by blow-moulding and which has a front wall 70 and a rear wall 35 as well as a hand grip recess 36 which is moulded into the upper region of its rear wall but does not penetrate the seat. The backrest 31 which is moulded to the shape of the body possesses at each of its lower corners a collar 71 which projects downwards and encloses an opening which opens downwards and has the crosssectional shape of the uprights 19.This shape of the openings continues over a substantial part of the height of the backrest 31 so that a cavity 73, adapted to the upright cross-section. is formed at the sides of the back support (Figure 9) and its longitudinal extension (at right-angles to the main extent of the backrest), corresponding to the greatest cross-sectional dimensions of the uprights, has the shape of an oblong hole.

This shape is larger than the thickness of the backrest so that a rim 74 is formed at the rearside of the backrest and circumscribes by about two thirds the upright 19, slipped into this socket. The upright 19 is thus encased on its two curved sides and on one straight side, i.e. the outside. by the seat.

The cavity 73 extends along the outside of the backrest 31 but its internal dimensions diminish upwards so that the uprights 1S) inserted through the openings only penetrate the backrest 31 to a preset height. This length is preferably 1/3 to 1/2 of the height of the backrest. The backrest, which is attached by being pressed on is thus well attached to the uprights 19, although the uprights could thereby end far below the upper edge of the chair, which makes savings in material possible. Above all the collar 71 encloses the uprights completely at one point and the shape of the cavity 73 described also ensures a secure guidance.

The thickened rim portion formed by the cavity 73 can pass about the entire upper edge of the backrest to improve its strength characteristics. Any desired means of attachment can secure the backrest against being removed.

The backrest described and its mounting ensure savings in materials and assembly advantages in the production of the frame.

The upper ends of the uprights are securely joined to each other and covered and a chair is created which has a particularly harmonious exterior.

The illustrated chair is strong and robust so that it lends itself to use in schools.

Furthermore the chair is stable and possesses rigidity.

WHAT WE CLAIM IS: 1. A chair seat comprising a hollow shell which has been blow-moulded and whose topside forming the seat face has ventilation holes which have been formed during the blow-moulding process.

2. A stackable chair having a metal frame which comprises two runners and two rearwardly inclined lateral uprights which are attached to the runners and between which a seat support is mounted, the chair having a backrest attached to the upper ends of the frame uprights and a seat on the seat support, the seat comprising a hollow shell which has been blow-moulded and having on its topside forming the seat face, ventilation holes which have been formed during the blow-moulding process.

3. A chair as claimed in claim 2, in which the seat support comprises a Ushaped seat supporting frame, the U-shape being closed at the front and the seat supporting frame extending round the edge region of the seat.

4. A chair as claimed in claim 3, in which the seat has at least one projection in the region of its front side which projection projects into a correspondingly dimensioned hole in the seat supporting frame.

5. A chair as claimed in claim 2, 3 or 4 in which the backrest joins upper free ends of the uprights together so that they have a fixed lateral distance apart.

6. A chair as claimed in claim 5 when appendent to claim 3 or 4 in which the seat has at each side at least one hole and the seat supporting frame has on its inside holes which are aligned therewith and in which a locking bar is provided and projects through the lateral holes in the seat and through the holes, aligned therewith in the seat supporting frame, the ends of the locking bar being introduced into the holes in the seat supporting frame by resiliently splaying out the seat supporting frame prior to the fitting of the backrest to the uprights.

7. A chair as claimed in claim 5 or 6, in which the backrest is blow-moulded.

8. A chair as claimed in claim 7 in which the backrest is provided at its underside with openings which lead into its interior and whose shape is adapted to the cross-section of the uprights. and in which the backrest is fitted by inserting the upper ends of the uprights into such openings.

9. A chair as claimed in claim 8. in which said openings in the backrest are provided in the lower lateral corner regions thereof and are directed downwardly and in which a cavity of corresponding crosssection extends from each such opening and parallel to the external lateral edges of the backrest.

1(). A chair as claimed in claim t). in which the cavity which extends from the openings and accommodates the upper end of the uprights forms a rim-like peripheral thickened portion of the blow-moulded

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Claims

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follow the shape of the seat topside.

As can be seen from Figures 1 and 6 to 9 the backrest 31 is also a hollow member of plastics material which is manufactured by blow-moulding and which has a front wall 70 and a rear wall 35 as well as a hand grip recess 36 which is moulded into the upper region of its rear wall but does not penetrate the seat. The backrest 31 which is moulded to the shape of the body possesses at each of its lower corners a collar 71 which projects downwards and encloses an opening which opens downwards and has the crosssectional shape of the uprights 19.This shape of the openings continues over a substantial part of the height of the backrest 31 so that a cavity 73, adapted to the upright cross-section. is formed at the sides of the back support (Figure 9) and its longitudinal extension (at right-angles to the main extent of the backrest), corresponding to the greatest cross-sectional dimensions of the uprights, has the shape of an oblong hole.

This shape is larger than the thickness of the backrest so that a rim 74 is formed at the rearside of the backrest and circumscribes by about two thirds the upright 19, slipped into this socket. The upright 19 is thus encased on its two curved sides and on one straight side, i.e. the outside. by the seat.

The cavity 73 extends along the outside of the backrest 31 but its internal dimensions diminish upwards so that the uprights 1S) inserted through the openings only penetrate the backrest 31 to a preset height. This length is preferably 1/3 to 1/2 of the height of the backrest. The backrest, which is attached by being pressed on is thus well attached to the uprights 19, although the uprights could thereby end far below the upper edge of the chair, which makes savings in material possible. Above all the collar 71 encloses the uprights completely at one point and the shape of the cavity 73 described also ensures a secure guidance.

The thickened rim portion formed by the cavity 73 can pass about the entire upper edge of the backrest to improve its strength characteristics. Any desired means of attachment can secure the backrest against being removed.

The backrest described and its mounting ensure savings in materials and assembly advantages in the production of the frame.

The upper ends of the uprights are securely joined to each other and covered and a chair is created which has a particularly harmonious exterior.

The illustrated chair is strong and robust so that it lends itself to use in schools.

Furthermore the chair is stable and possesses rigidity.

WHAT WE CLAIM IS:

1. A chair seat comprising a hollow shell which has been blow-moulded and whose topside forming the seat face has ventilation holes which have been formed during the blow-moulding process.

2. A stackable chair having a metal frame which comprises two runners and two rearwardly inclined lateral uprights which are attached to the runners and between which a seat support is mounted, the chair having a backrest attached to the upper ends of the frame uprights and a seat on the seat support, the seat comprising a hollow shell which has been blow-moulded and having on its topside forming the seat face, ventilation holes which have been formed during the blow-moulding process.

3. A chair as claimed in claim 2, in which the seat support comprises a Ushaped seat supporting frame, the U-shape being closed at the front and the seat supporting frame extending round the edge region of the seat.

4. A chair as claimed in claim 3, in which the seat has at least one projection in the region of its front side which projection projects into a correspondingly dimensioned hole in the seat supporting frame.

5. A chair as claimed in claim 2, 3 or 4 in which the backrest joins upper free ends of the uprights together so that they have a fixed lateral distance apart.

6. A chair as claimed in claim 5 when appendent to claim 3 or 4 in which the seat has at each side at least one hole and the seat supporting frame has on its inside holes which are aligned therewith and in which a locking bar is provided and projects through the lateral holes in the seat and through the holes, aligned therewith in the seat supporting frame, the ends of the locking bar being introduced into the holes in the seat supporting frame by resiliently splaying out the seat supporting frame prior to the fitting of the backrest to the uprights.

7. A chair as claimed in claim 5 or 6, in which the backrest is blow-moulded.

8. A chair as claimed in claim 7 in which the backrest is provided at its underside with openings which lead into its interior and whose shape is adapted to the cross-section of the uprights. and in which the backrest is fitted by inserting the upper ends of the uprights into such openings.

9. A chair as claimed in claim 8. in which said openings in the backrest are provided in the lower lateral corner regions thereof and are directed downwardly and in which a cavity of corresponding crosssection extends from each such opening and parallel to the external lateral edges of the backrest.

1(). A chair as claimed in claim t). in which the cavity which extends from the openings and accommodates the upper end of the uprights forms a rim-like peripheral thickened portion of the blow-moulded

backrest, which portion projects beyond the rear face of the backrest.

11. A chair as claimed in claim 10, in which the peripheral thickened portion continues into the upper edge of the backrest.

12. A chair as claimed in any of claims 9 to 11. in which each opening is located in the region of a collar which projects downwardly beyond the lower edge of the backrest and embraces the upper end of the respective upright in the region of the opening.

13. A chair as claimed in any of claims 9 to 12. in which the portions of the backrest which define each cavity which accommodates the upper end of the respective uprights circumscribe them by about twothirds.

14. A chair as claimed in any of claims 7 to 13 in which the length of the end regions of the uprights which are inserted in the blow-moulded backrest is substantially no more than half the height of the backrest.

15. A chair seat constructed substantially as herein described with reference to and as illustrated in Figures 2. 3 and 4 of the accompanying drawings.

16. A chair seat as claimed in claim 15 when made by the blow-moulding apparatus herein described with reference to and as illustrated in Figure 5 of the accompanying drawings.

17. A chair constructed substantially as herein described with reference to and as illustrated in Figures I to 4 of the accompanying drawings.

18. A chair as claimed in claim 17 having a backrest constructed substantially as herein described with reference to and as illustrated in Figures 6 to 9 of the accompanying drawings.

19. A method of blow-moulding a chair seat in the form of a hollow shell with ventilation holes in its topside forming the seat face, in which, during or after the blowing operation and whilst the softened blow-moulded shell is still in the blowmould, numerous pins are pressed through respective apertures in one side of the blow-mould into the topside of the seat until through holes are formed.

20. Blow-moulding apparatus for making a chair seat in the form of a hollow shell with ventilating holes in its topside forming the seat face, in which a blow-mould member for moulding the topside of the seat has numerous pins which can be introduced into the mould interior through respective apertures in the blow-mould member during or after the blowing operation in order to pierce the topside of the seat.

21. Apparatus as claimed in claim 2(), in which the pins are dimensioned and arranged according to the seat shape and are disposed on a common plate.

22. Apparatus as claimed in claim 2() or 21, in which the pins each have a larger diameter shank corresponding to the diameter of the apertures and a smaller diameter tip which is joined thereto at either a fillet or a conical shoulder which lies in the region of the mould surface when the pins extend into the mould interior.

23. A method of blow-moulding a chair seat substantially as herein described with reference to Figure 5 of the accompanying drawings.

24. Chair seat blow-moulding apparatus constructed and adapted to operate substantially as herein described with reference to and as illustrated in Figure 5 of the accompanying drawings.