WO1997010138A1

WO1997010138A1 - Vehicle cab and method for assembling such a cab by welding

Info

Publication number: WO1997010138A1
Application number: PCT/SE1996/001138
Authority: WO
Inventors: Yngve Ahl; Nils Norlin; Staffan Sjöström
Original assignee: Scania Cv Aktiebolag
Priority date: 1995-09-14
Filing date: 1996-09-12
Publication date: 1997-03-20
Also published as: BR9606644A; SE504608C2; SE9503172D0; SE9503172L; DE19680916T1

Abstract

Vehicle cab incorporating a cab frame (4) with a welded roof structure (6). The roof structure comprises partly a roof middle section (26) and partly a pair of roof side sections (28) which are welded to opposite edge portions of the roof middle section (26). The welded connections between the roof middle section and the roof side sections from sheet metal flange joints between sheet metal flanges (26', 28') (which are connected to one another and are directed outwards) of the roof middle section and the respective adjacent roof side sections. The invention also concerns a method of erecting and assembling the aforesaid type of vehicle cab. The roof middle section (26) is first positioned on top of the frame (4) and is welded in a front edge region (36) and in a rear edge region (38). Necessary supplementary welding of the cab frame can be done via the still incomplete roof areas and only thereafter are a pair of roof side sections (28) welded to opposite sides of the roof middle section (26).

Description

Vehicle cab and method for assembling such a cab by welding

The present invention relates partly to a vehicle cab of the kind indicated in the preamble to patent claim 1 and partly to a method of the kind indicated in the preamble to claim 3.

A vehicle cab of the kind in question incorporates a cab frame and a roof structure which is fastened to the cab frame and which comprises sheetmetal units and/or sheetmetal panels and sheets of metal welded together. The cab frame is made up of the primary structural components whose purpose is to absorb and distribute the loading forces and moments to which the cab may be subjected during normal operation and in an accident situation such as a vehicle collision. These structural components consist inter alia of various types of hollow sheetmetal members and reinforced sheetmetal panels.

State of the art

Technical problems of manufacture arise particularly in the production of cabs for trucks and other commercial utility vehicles, inter alia because the width of the cab may be greater than the maximum width of sheetmetal available for the purpose.

Sheetmetal of the kind used in the manufacture of vehicle cabs can at present be supplied in a maximum width of 2500 mm. This means that in the manufacture of vehicle cabs which have roofs of this width or a greater width it is necessary to join sheets of metal in the roof structure. The same also applies if the roof structure is, for example, provided with a heightened portion. The most usual practice in both cases is for the sheets to be joined in such a way that the joint is concealed as seen from outside. Such joints are made by welding on the inside of the cab roof, i.e. from within the cab. In this context it may be noted that cab roofs for trucks almost without exception (for traditional reasons?) have been designed so that any joints are not visible from outside. Joining such roof sheets by welding on the inside of the roof results in problems in the case of automated welding (robot welding) because of difficulties in reaching the welding points concerned.

The technique hitherto applied of welding on the inside of the cab roof, i.e. welding from within the cab, has therefore come to be a prevalant standard method in truck cab production, but this method has the clear disadvantage that manufacture/welding involves special time-consuming and expensive operations arising from the aforesaid difficulties in reaching the relevant welding points in a rational manner.

Another known practice in the production of vehicle cabs has been to manufacture the whole roof structure separately so that it can thereafter be welded as a complete unit to the cab frame. The disadvantage of this procedure is that when the welding has been done the whole cab roof is complete and in subsequent welding work within the cab it is only possible to introduce the welding robot used into the cab via the windscreen aperture or one of the door apertures.

Another factor in a known vehicle cab design with a roof structure which includes two roof members running in the longitudinal direction of the vehicle (the direction of vehicle movement) is that the front ends of these members have to be fitted into individual fastening recesses in the windscreen member. This constructional arrangement means that accurate fitting of the front ends of the roof members is required at the time of assembling/welding together the cab and the relating roof structure.

Objects of the invention

The primary object of the invention is to create a vehicle cab which has a roof structure such that the latter's middle section (roof centre section) can without difficulty be welded to the cab frame and that the roof middle section thus welded in will not cause any hindrance to access for carrying out subsequent automated welding work inside the cab, regardless of whether the welds are on the cab frame itself or on the roof middle section.

With such a roof middle section welded in, it will be easy for the interior of the cab to be reached from the outside (e.g. by a pair of welding tongs belonging to a welding robot) not only via the windscreen aperture and the door apertures but also via the still incomplete side areas of the cab roof, i.e. the open spaces on either side of the roof middle section (roof centre section). The roof members belonging to the roof middle section (roof centre section) will also be easy to reach for welding to a windscreen member and to a loadbearing section of a rear element of the cab frame. This will not require any accurate fitting of the front ends of the roof members into recesses in the windscreen member.

Another object of the invention is that the vehicle cab roof structure should be composed of the aforesaid roof middle section (roof centre section) and a pair of roof side sections weldable from the outside (the top) of the roof to the respective side edge portions of the roof middle section (roof centre section).

A further object of the invention is to provide a method which can be used in erecting and assembling a vehicle cab of the kind intended according to the invention.

Description of the invention

The aforesaid objects concerning vehicle cab construction are achieved according to the invention by cabs of the kind indicated in patent claim 1 exhibiting the features indicated in the characterising part of that claim.

Vehicle cabs according to the invention may additionally exhibit the further developing features which are indicated in claim 2.

The fundamental idea of the invention is that the vehicle cab roof structure should consist partly of a preferably centrally positioned roof middle section incoφorating roof members and partly of a pair of roof side sections which are welded to opposite side edge portions of the roof middle section by welded connections penetrating into sheetmetal flange joints which extend in the longitudinal direction of the cab and embrace sheetmetal flanges (which are directed outwards and are welded to one another) of the roof middle section and the respective adjacent roof side section. In this roof structure the front edge region of the roof middle section is welded to a windscreen member incoφorated in the cab frame, and the rear edge region of the roof middle section is welded to a loadbearing section of a rear element of the cab frame. The fact that the roof middle section is united with the two roof side sections adjacent to it by welded connections arranged in sheetmetal flanges directed outwards of the roof middle section and the adjacent roof side sections makes it very easy to execute the welding from the outside of the roof, thereby making it very easy to reach the sheetmetal flange joint, e.g. for spot welding by means of an automatically controlled pair of welding tongs of a welding robot.

The external appearance disadvantage of welded sheetmetal flange joints of the roof structure being visible on the outside of the roof can easily be remedied by the sheetmetal flanges welded together being provided with longitudinal cover strips which embrace the flanges and perform the double function of providing corrosion protection and concealing the actual joints.

The aforesaid object of the method according to the invention is achieved by the method being characterised by the operations indicated in the characterising part of patent claim 3.

Further developing features of this method are also indicated in claims 4 and 5.

The fundamental idea of the method according to the invention is that a roof middle section which is to form part of the roof structure is positioned preferably centrally on top of the frame and is welded to the latter by a front edge region of the middle section being welded to a windscreen member incoφorated in the frame, while a rear edge region of the middle section is welded to a loadbearing rear element of the cab frame. A welding robot is thereafter introduced into the space within the cab via the still open spaces at and inside the side edge portions of the roof middle section and is then used to carry out necessary supplementary welding work on both the cab frame and the roof middle section. This welding may, for example, include welding roof members incoφorated in the middle section to the windscreen member. To this end, the roof members are quite simply placed in position with their end surfaces in contact respectively with the top of the windscreen member and with an upper transverse member which supports the roof and is situated in the rear part of the cab frame. This does not require any accurate fitting of the front ends of the roof members into recesses in the windscreen member. When the supplementary welding work has been completed in the space within the cab, a pair of roof side sections are welded to opposite side edge portions of the roof middle section by sheetmetal flanges directed outwards of the roof middle section and the adjacent roof side sections being welded together from outside, thereby forming external sheetmetal flange joints directed outwards on the outside of the roof structure.

Before the roof side sections are welded to the side edge portions of the roof middle section, a welding robot may be used via the still open spaces at7inside the side edge portions of the middle section to weld further panels and/or sheets of metal to the cab frame, e.g. cab sidewall panels.

It is advantageous to provide the welded sheetmetal flange joints directed outwards between the roof middle section and the roof side sections with longitudinal cover strips made of non-rusting material, such as a suitable plastic material, which embrace the flanges.

It is advantageous to use for welding roof members incoφorated in the middle section of the roof structure to the windscreen member a welding robot which has the two arms of its pair of welding tongs inserted through puφose-made access apertures in the sidewalls (which face towards the interior of the cab) of, on the one hand, the windscreen member, which takes the form of a hollow sheetmetal member, and, on the other hand, the adjacent end portion of the longitudinal roof member, which likewise takes the form of a hollow sheetmetal member.

Brief description of the drawings

The invention will now be described and explained further below with reference to the attached drawings which show parts of a vehicle cab according to the invention, as follows: Fig. 1 shows in perspective and in partially exploded view a vehicle cab according to the invention;

Fig. 2 is a schematic cross-section through the sheetmetal flange joint between the roof middle section and one of the roof side sections welded to it, shown on a larger scale; Fig. 3 is a schematic X-ray depiction of one half of a roof structure for a vehicle cab according to the invention; and

Fig. 4 is a very schematic depiction on a larger scale of the connection point between the windscreen member and the longitudinal roof member at section IV-IV in Fig. 3, showing how a pair of welding tongs may be applied to and engaged with relevant parts in this welded connection region.

Description of an embodiment

Fig. 1 shows somewhat schematically a perspective view of a vehicle cab 2 according to the invention. This vehicle cab is intended for a freight vehicle not otherwise depicted. The vehicle cab is composed of a cab frame 4 and a roof structure 6 which is fastened to the upper part of the frame. The roof structure comprises sheetmetal units and/or sheetmetal panels and sheets of metal welded together. The cab frame 4 is conventionally composed of a multiplicity of horizontal and vertical members and cab pillars. The cab frame thus includes two cab front pillars 8, two cab middle pillars 10 and two cab rear pillars 12. The cab front pillars 8 are joined together at the top by a horizontal windscreen member 14, and the cab rear pillars 12 are connected together at the top by a transverse rear wall member 16. The cab rear wall structure also includes further members such as the members 18, 20 and 22 shown in the drawings. Longitudinal sill members 24 connecting the cab front, middle and rear pillars are situated conventionally below the door apertures in the cab frame sidewall structures. The members and pillars incoφorated in the cab frame are conventionally connected to one another primarily by welded connections.

The roof structure 6 comprises partly a centrally positioned roof middle section 26 and partly a pair of roof side sections 28 adjacent to opposite side edge portions of the roof middle section 26. Fig. 1 shows an exploded view of only one of these two roof side sections 28, viz. that which is intended to be welded above the vehicle cab left door aperture 30. It also shows, immediately below the roof side section 28, a sidewall panel 32 belonging to the vehicle cab sidewall structure. Not only the roof middle section 26 but also the sidewall panel 32 and the vehicle cab floor structure with the quite general notation 34 may conventionally incoφorate strengthening elements, e.g. in the form of members which absorb forces and moments.

The bent-downwards front edge region 36 of the roof middle section 26 is welded to the windscreen member 14 incoφorated in the cab frame 4. The likewise bent-downwards rear edge region 38 of the roof middle section 26 is welded to the upper member 16 incoφorated in the vehicle cab rear wall.

As described above, the roof structure 6 also includes the two roof side sections 28, only one of which is depicted in Fig. 1, viz. that which is intended for the vehicle cab left side. This roof side section 28 is shown separated from the side edge portion of the roof middle section 26 so that internals of the cab frame may be visible in the drawing. The two roof side sections 28 belonging to the roof structure are nevertheless intended to be welded to opposite side edge portions of the roof middle section 26. The edge region 40 on the opposite side of the roof side section 28 from the roof middle section is intended to be welded to the sidewall member 42 which delineates the top of the door aperture 30.

The welded connections between the roof middle section 26 and the two roof side sections 28 penetrate into and form sheetmetal flange joints which extend in the longitudinal direction of the vehicle cab, i.e. the vehicle movement direction. It is in principle advantageous that these two sheetmetal flange joints be executed in the manner indicated in the schematic cross-section in Fig. 2. As may be seen in Fig. 2, both the roof middle section 26 and the adjacent roof side section 28 have in the joint region a sheetmetal edge portion or sheetmetal flange 26' and 28' respectively which are bent upwards, i.e. directed outwards from the interior of the vehicle cab. These mutually adjacent sheetmetal flanges 26' and 28' are welded together preferably by means of spot welds 44 and thereby form protruding joint regions on the outside of the roof structure 6. The puφose of this type of sheetmetal joint is specifically to provide a joint which is readily accessible for welding in that it can be welded from the outside of the vehicle cab and the roof structure. This makes it possible to join together the parts which form the external sheetmetal portions of the roof structure much more easily than is possible by internal welding within the vehicle cab. In practice it is probably advantageous to provide the two welded sheetmetal flange joints 26', 44,28' directed outwards with longitudinal cover strips 46 which form corrosion protection concealing the joints. It is advantageous that these cover strips 46 be designed to engage over and about the outer parts of the sheetmetal flanges 26' and 28', e.g. in the manner schematically depicted in Fig. 2. The cover strips 46, which may for example be made of a suitable plastic, form corrosion protection which effectively conceals the external sheetmetal flange joints running in the longitudinal direction of the vehicle cab.

The fact that the vehicle cab is constructed in the manner depicted in Fig.1 makes it possible to apply a very rational method in erecting and assembling the vehicle cab. According to this method, the roof middle section 26 is first positioned on top of the cab frame 4 and is then welded to it partly by welding the front edge region 36 to the windscreen member 14 and partly by welding the rear edge region 38 to the rear wall member 16.

The thus freely accessible spaces in the regions between the members 42 and the side edge portions of the roof middle section make it possible for welding robots to be introduced therein or to reach into the vehicle cab in order to carry out any necessary supplementary welding work on the vehicle frame 4 and the roof middle section 26. This may for example involve welding of longitudinal roof members belonging to the roof middle section 26 which extend between the windscreen member 14 and the member 16.

When this necessary supplementary welding work has been completed, the two roof side sections 28 are then welded to the respective opposite side edge portions of the roof middle section 26 by the sheetmetal flanges 26' and 28' directed outwards of the roof middle section and the respective adjacent roof side sections 28 being welded together from outside in order to form the aforesaid external sheetmetal flange joints running in the longitudinal direction of the vehicle on the outside of the roof structure 6.

Before the two roof side sections 28 are welded to the side edge portions of the roof middle section 26, welding robots may also be used via the aforesaid still open spaces in the regions outside the side edge portions of the middle section to weld further panels and/or sheets of metal to the cab frame 4, e.g. the sidewall panels 32 on opposite sides of the cab frame 4.

The procedure described above of welding the respective roof side sections 28 in as complete units to the roof middle section 26 and the sidewall panel 32, which is also welded to the cab frame 4 during the erection of the frame, provides good accessibility for welding the joints in the regions notated A, B, C and D in Fig.l. The fact that according to the invention spaces are kept open as long as possible to allow welding robots to be introduced into the interior of the cab frame makes it possible by robot welding to reach from outside the relevant welding areas of the front portion, roof middle section, floor structure and side sections of the cab frame.

The mode of construction and the welding method which are subject matter of the present invention thus afford substantial structural design advantages over the known technique whereby it is usual from the very beginning to join together the whole roof structure and weld it to the cab frame. The fact that in that case the whole roof is complete from the very beginning means that there are no openings or spaces to make it possible rationally to reach relevant welding points of the cab frame. Consequently, when welding has to be carried out within the cab, welding robots can only be introduced into the cab via the windscreen aperture or the door apertures. This inevitably means substantially more difficult and more time-consuming patterns of movement for the respective welding robots than those which are possible according to the present invention.

Reference is now made to Fig. 3 which is a perspective view showing how easy it is to place a longitudinal roof member 48 belonging to the roof middle section 26 in position between the windscreen member 14 and the rear member 16 before welding it in between these two members. The fact that in this case the roof side section 28 has not yet been welded to the roof middle section 26 and the member 42 makes it easy to use a pair of welding tongs from outside to weld the ends of the roof member 48 to the members 14 and 16.

As an example of this welding in of the ends of the member 48, reference is made to Fig. 4 which shows extremely schematically how such welding by welding tongs can be executed at the hollow front end of the roof member 48 at section IV-IV in Fig. 3. The roof member 48, which takes the form of a hollow sheetmetal member, has in this case an access aperture 50 on the underside of the member 48 facing towards the interior of the vehicle cab. Correspondingly, the inside of the windscreen member 14, which likewise takes the form of a hollow sheetmetal member, has an access aperture 52 for carrying out spot welding. It is advantageous for this spot welding of the front end of the roof member 48 to the windscreen member to be executed by means of a pair of welding tongs 54 which is operated by a welding robot and which has its lower arm 56 introduced through the aperture 52 and its upper arm 58 introduced through the aperture 50 in the roof member 48. The welding tongs 54 can thus be introduced into the vehicle cab via the in this case still open roof side regions which are only closed later by the two roof side sections 28. This takes place at a later stage of the frame erection and the roof welding. Fig. 4 also depicts schematically an outer roof cover sheet 60. The lower edge region 62 of this cover sheet is intended to be welded to a downward extension 64 of the front sheetmetal wall of the windscreen member 14. The outer contour of this outer roof cover sheet 60 is also suggested in Fig. 3 by the contour line 60'.

Claims

Patent claims

1. Vehicle cab incoφorating a cab frame (4) and a roof structure (6) which is fastened to the frame and which comprises sheetmetal units and/or sheetmetal panels and sheets of metal welded together, characterised in that the roof structure (6) comprises partly a preferably centrally positioned roof middle section (26) with a front edge region (36) welded to a windscreen member (14) incoφorated in the cab frame and a rear edge region (38) welded to a loadbearing section (16) of a rear element of the cab frame, and partly a pair of roof side sections (28) which are welded to opposite side edge portions of the roof middle section (26), and that the welded connections between the roof middle section (26) and the roof side sections (28) penetrate into and form sheetmetal flange joints which run in the longitudinal direction of the cab (i.e. the vehicle movement direction) and which embrace sheetmetal flanges (26',28') of the roof middle section, which are welded to one another and directed outwards, and the respective adjacent roof side sections.

2. Vehicle cab according to claim 1 , characterised in that the two welded sheetmetal flange joints directed outwards at opposite side edge portions of the roof middle section are provided with longitudinal cover strips (46) which embrace the flanges (26',28') and which form corrosion protection concealing the joints.

3. Method for erecting and assembling a vehicle cab by a roof structure (6) which comprises sheetmetal units and/or sheetmetal panels and sheets of metal welded together being welded to a cab frame (4), characterised in that a roof middle section (26) which is to form part of the roof structure is positioned preferably centrally on top of the frame (4) and is welded to the latter by a front edge region (36) of the middle section (26) being welded to a windscreen member (14) incoφorated in the frame and by a rear edge region (38) of the middle section being welded to a loadbearing rear element ( 16) of the frame, that one or more welding robots are wholly or partly introduced into the space within the cab via the open spaces at and inside the side edge portions of the roof middle section in order to carry out any necessary supplementary welding work on the cab frame (4) and the roof middle section (26), e.g. welding of roof members (48) incoφorated in the middle section to the windscreen member (14), that a pair of roof side sections (28) are thereafter welded to opposite side edge portions of the roof middle section (26) by sheetmetal flanges (26',28') directed outwards of the roof middle section and the respective adjacent roof side sections being welded together from outside in order to form external sheetmetal flange joints running in the longitudinal direction of the cab (i.e. the vehicle movement direction) on the outside of the roof structure.

4. Method according to claim 3, characterised in that before the roof side sections (28) are welded to the side edge portions of the roof middle section (26), the relevant welding robot or robots are also used via the open spaces at/inside the side edge portions of the middle section to weld further panels and or sheets of metal to the cab frame, e.g. cab sidewall panels.

5. Method according to claim 3 or 4, characterised in that the two welded sheetmetal flange joints (26',28') directed outwards at the opposite side edge portions of the roof middle section (26) are provided with longitudinal cover strips (46) which embrace the flanges and which form corrosion protection concealing the joints.