Patent Publication Number: US-2003222087-A1

Title: Base pan for a safety workbench

Description:
[0001] The invention pertains to a base pan for placement in the lower section of the workspace of a safety workbench.  
       [0002] Base pans for safety workbenches are needed for the collection of quantities of material, such as liquids, from the workspace. These quantities of material move from the work plate in the workspace via air intake slots or slits in the work plate area into the base pan.  
       [0003] The disadvantage of these base pans is that small quantities of material that collect in the base pan do not flow by themselves into a collection area. By forming a dished area in the base pan, a drain direction can be created for the quantities of material. This carving of the base pan requires additional, complex work steps which are associated with additional expense and time. Also, the achieved results with regard to the running off of liquids are not satisfactory. Moreover, due to the dishing, stresses appear in the component which result in undefined “bending states” of the base pan.  
       [0004] Another possibility for the manufacture of base pans with a defined collection area is the deep drawing of sheet metal. These deep-drawn sheet metal base pans are very expensive in small quantities, and the large expenses for machine tools and machinery are not economically feasible.  
       [0005] Accordingly, the problem of the invention is to design a base pan for safety workbenches with a defined collection area which can be manufactured at low cost in small quantities. The manufacture should involve as few additional and expensive work steps as possible.  
       [0006] The solution to this problem is obtained for the base pan according to claim 1 and the method of manufacture according to claim 12. The preferred embodiments and process variants are indicated in the specific subordinate claims.  
       [0007] The base pan according to the present invention features a bottom area surrounded by side walls, in the lowest region of which there is a collection area, such that the bottom area is sloped downward, at least in part, in the direction of the collection area and that the height of the side walls running toward the collection area increases in the direction of the collection area.  
       [0008] The bottom area of a base pan according to the invention can thus also have horizontally running sections of the bottom area. At least one section of the bottom area is sloped in the direction of the collection area. The bottom area can also be of stepped design.  
       [0009] In order to ensure a uniform run-off of the quantities of material, it is preferred that the entire surface of the bottom area be essentially at a decline to the collection area; preferably it will decline in a continuous manner. The height of the side walls thus will increase continuously toward the collection area. In this case, the collection area is located preferably in one corner of the bottom area. The collected liquid can be removed quite easily from this collection area. The liquid can be removed manually from the collection area, or the liquid can leave the collection area through a drain with an opening in the bottom area. The drain opening can have various forms. It can be in the form of an elongated hole or it can be circular or it can have any other possible shape. In addition, a closable flow-off line can be provided at the drain.  
       [0010] In another embodiment according to the present invention, the bottom area can be sloped in the direction of one of its lateral edges or a portion of its lateral edges. Preferably, the slope is also continuous here. The collection area in this case is then located in the area of one edge of the bottom area of the base pan.  
       [0011] The collection area can also be located essentially in the middle of one lateral edge of the bottom area. The side wall neighboring the collection area is then divided into two side wall sections, each of which can run from the corners of the side wall to the collection area. In this embodiment form, the height of the side wall sections increases in the direction of the collection area. Preferably the slope is again continuous, so that the height of the side wall sections also increase continuously. The maximum height of the side wall is thus located in the middle, where the side wall sections abut each other, while the minimum height of the side wall is formed at its side ends.  
       [0012] As described above, according to the invention, the height of the side walls increases toward the collection area. Thus, not all side walls of the base pan need have a changing height. Accordingly, it is possible that at least one side wall or one section of a side wall has an essentially constant height across its length. It is then expedient to place the section of the bottom area adjoining this side wall in a horizontal plane.  
       [0013] In order to save space and material, the bottom area may be sloped in the horizontal direction only as much as necessary to ensure a sufficient run-off of liquid. An angle of slope between 0.5° and 10°, in particular between 1-3°, is recommended. The side walls can enclose an angle from 90-150° to the bottom area, and an angle of between 120-140° is preferred.  
       [0014] The mounting of the base pan in a safety workbench can occur essentially by any means of the prior art. Accordingly, the upper edges of the side walls bending away from the bottom area run preferably essentially in a plane, in particular, in an essentially horizontal plane.  
       [0015] The bottom pan seals the working space on the bottom. For sealing the bottom pan in the safety workbench, it is preferable to use conventional sealing materials.  
       [0016] In order to seal the corners of the base pan, the front edges of mutually adjoining side walls or sections of side walls are joined together, preferably by welding.  
       [0017] The invention also pertains to a method for the manufacture of a base pan. In this regard, it is produced by bending of the side walls from a piece of sheet metal in such a way that the bent edges, which correspond to the lateral edges of the bottom area of the base pan, run at an angle to the upper edges of the side walls, so that during bending, the side walls or sections of side walls surrounding the bottom area are produced with an increasing height in the direction of the collection area.  
       [0018] With regard to the manufacturing method, the advantage is that only simple and low-cost tools and machinery are required. Starting with the sheet metal, the angled base pan can be cut out from a single piece according to the present invention. The cutting of the sheet metal can be handled either by punching or by today&#39;s very low cost and flexible laser cutting methods, for example. Laser cutting is particularly suitable for the manufacture of small quantities since no additional tool costs are incurred, in contrast to punching. The bending or folding can be handled with a conventional folding or bending press.  
       [0019] Base pans according to the present invention can thus be manufactured in small quantities at low cost and in a simple manner.  
       [0020] In order to conserve materials, the pattern of the base can be cut from an essentially rectangular piece of sheet metal. Preferably, a slightly trapezoidal piece of sheet metal is used as starting material for the method of the invention.  
       [0021] In order to simplify the manufacturing method for the base pan according to the present invention, before the folding of the side walls, cut-outs (hereinafter called wedges) are cut from the sheet metal in the vicinity of mutually adjoining side walls or sections of side walls. The wedges are located basically in the corners of the base pan. If the collection area is located in the region between two sections of the side walls, then the wedges can also be cut in the middle region of side walls. The collection area of the finished base pan is then located accordingly in the middle region of the corresponding lateral edge of the bottom area.  
       [0022] Preferably the side walls run at an angle of 90-150°, in particular 120-140°, with respect to the bottom area. The reasons for this, among others, are that the quantities of material can be more easily collected and can thus be guided more easily to the collection area.  
       [0023] The upper region of the base pan is configured preferably as in conventional base pans, in order to fit it into state-of-the-art safety workbenches. Therefore, the sheet metal in the region of the upper side walls of the base pan along the upper edges of the base pan slants outwardly with respect to the bottom area.  
       [0024] As one of the final work steps, the sheet metal edges of neighboring side walls and/or of outward angled sheet metal areas are joined together, preferably by welding. 
     
    
    
     [0025] The invention will be explained in greater detail below with reference to the drawing.  
     [0026]FIG. 1 shows a schematic side view of a safety workbench with a built-in base pan according to the present invention.  
     [0027]FIG. 2 shows a schematic developed top view of the base pan of FIG. 1 according to the present invention, after it has been cut out from the sheet metal.  
     [0028]FIG. 3 shows a schematic oblique view of the base pan of FIG. 1 according to the present invention.  
     [0029]FIG. 4 shows a schematic front view of the base pan of FIG. 1 according to the present invention.  
     [0030]FIG. 5 shows a schematic side view of the base pan of FIG. 1 according to the present invention.  
     [0031]FIG. 6 shows a schematic top view of the base pan of FIG. 1 according to the present invention. 
    
    
     [0032] The safety workbench  1  illustrated in FIG. 1 corresponds essentially to a conventional safety workbench  1 , like that described in DE 44 41 784 C2, for example. A frame  2  encloses a workspace  3  in which samples can be processed. On the front side of the safety workbench  1  (the left side in the figure) the workspace  3  is accessible through a work opening, which can be sealed off with a front plate. During the processing of the samples in the workspace  3  and for cleaning of the work plate  4 , small quantities of material can fall or flow through air intake slots  5  in the work plate  4  or slits between sections of the work plate into the base pan  6  located underneath. The air intake slots  5  are necessary to allow air to circulate within the workbench. The base pan  6  has dimensions so that it can fit into the frame  2 . In this regard it is important that the base pan  6  seal off the work space  3  from below, so that no materials can escape from the safety workbench  1 . Preferably the collection area  9  of the base pan  6  is located at the longitudinal side of the work opening, so that, if necessary, residual material can be pushed along by hand to the collection area  9 . The top edges  11  of the side walls  8  are located in a horizontal plane, so that the work plate  4  can be set flat onto the base pan  6 . The barrier  16  of the base pan  6  fits flushly against the work plate  4 , as illustrated in FIG. 1, and in accordance with the state of the art.  
     [0033] The starting point for the manufacture of the base pan  6  is a corrosion-resistant piece of sheet metal, and a polished stainless steel type is recommended. The advantage of this type of sheet metal is that it allows liquids and quantities of material collected in the base pan  6  to flow off easily. The sheet metal also has a film coating to protect it during processing. The film can be entirely removed only after completion of manufacture of the base pan  6 .  
     [0034] A flat template of the base pan  6  of the invention is cut out from the sheet metal, as is illustrated in FIG. 2. Preferably the template is cut from the sheet metal by using a laser. This method is low in cost for small quantities manufactured and is very flexible with regard to the shapes to be cut.  
     [0035] Therefore, laser cutting is an excellent method for forming the required cut-outs, each of differing size, from the corners of the flat template of the base pan  6 . These cut-outs, hereinafter called wedges  12 , are formed so that when bending the side walls  8 , the sheet metal material does not overlap at the front of the side walls  8 , and thereby produces flush weld at the front of the side walls  8 . The lengths of the front sides of the side walls  8  thus correspond essentially to the lengths of the sides of the wedges  12 . The length of the front sides of the side walls  8  is determined first by the height of the side walls  8 , and second by the angle to be cut between the bottom area  7  and the side walls  8 . The height of the side walls  8  running to the drain increases in the direction of the collection area  9 , so that the collection area  9  is located at the lowest point of the bottom area  7 . In this case, the result is that the front sides of the side walls  8  are longest in the close vicinity of the collection area  9 , and the front sides of the side walls  8  that are farthest from the collection area  9  are the shortest. The smallest wedges  12  are thus farthest from the collection area  9  and the largest are closest to the collection area  9 . From the requirement for continuously increasing height of the side walls  8  in the direction of the collection area  9 , in the present example, the result is that the bending edges  10 —which correspond to the lateral edges of the bottom area  7  of the base pan  6 —separate at an angle toward the subsequent upper edges  11  of the side walls  8 .  
     [0036] At each side wall  8  there is at least two additional rectangular shoulders, which are produced by additional bending. Thus, they are basically not visible at all on the angled, punched sheet metal, as is indicated in FIG. 2, but rather are combined into a single rectangular shoulder. The first rectangular shoulder is used to produce a horizontal frame with horizontal frame surfaces  13  around the pan. The second rectangular shoulder  14 , which is bent at a right angle to the horizontal frame surface  13 , is used to join the base pan  6  flush to the frame  2  of the safety workbench  1 . Two additional right-angle shoulders adjoin the vertical shoulder  14  on what will be rear side wall  8  of the base pan  6 ; once bent, these shoulders form a type of hook. Four additional right-angle shoulders adjoin what will be front side wall  8  at the shoulder for the horizontal frame surface  13 ; after these additional shoulders are bent, they produce a barrier  16  with a terminating fold for hook engagement. This barrier  16  prevents fluids from easily escaping from the workspace  3 . This barrier  16  is visible as a U-shaped shoulder in FIG. 5. The last bent surface of the barrier  16  (which forms a closed folding border) can be used for hooking and for sealing of the base pan  6  in the safety workbench  1 .  
     [0037] For better understanding, the edges which are bent over are indicated by a dashed line in FIG. 2.  
     [0038] In order to attach the base pan  6  to the frame  2  of the safety workbench  1 , holes  15  are drilled in the shoulder for the vertical side wall  14 , through which suitable fasteners can be installed. The vertical side walls  14  have lower sealing edges which run essentially horizontal in the finished base pan  6 .  
     [0039] The front sides of the neighboring, right-angled shoulders are then welded together at the corners.  
     [0040] A larger drilled hole serving as collection area  9  is located on the imaginary line running to the peak of the largest wedge  12 , that is, in one of the corners of the bottom area  7  of the finished base pan  6 .  
     [0041]FIG. 3 provides an oblique view of the base pan  6  according to the present invention, in the final assembled state. The base pan  6  has a collection area  9 , which is designed here as a drain with a hole-like opening, in the front left corner with respect to the working opening of the safety workbench  1 . As can be seen in the left side wall  8  and in the rear side wall in FIG. 3, the bending edges  10  run at an angle to the top edges  11  of the side walls  8 . The horizontal frame surfaces  13  are presented here as thinner at the front sides of the base pan  6  than at the longitudinal sides. Overall, the frame surface  13  has an essentially rectangular profile, as do conventional base pans.  
     [0042]FIGS. 4 and 5 show the different angles of gradient of the bottom area  7  with respect to the horizontal, in the longitudinal and transverse direction of the base pan  6 .  
     [0043] Once again, FIG. 6 clearly shows the bottom area  7  with the bending edges  10  running at an angle to the upper edges  11  of the side walls  8 . The essentially rectangular profile of the frame surface is clearly portrayed in this view.  
     LIST OF REFERENCE SYMBOLS  
     [0044] 1  Safety workbench  
     [0045] 2  Frame  
     [0046] 3  Workspace  
     [0047] 4  Work plate  
     [0048] 5  Air intake slot  
     [0049] 6  Base pan  
     [0050] 7  Bottom area  
     [0051] 8  Side wall  
     [0052] 9  Collection area  
     [0053] 10  Bent edge  
     [0054] 11  Top edge of side wall  
     [0055] 12  Wedge  
     [0056] 13  Horizontal frame surface  
     [0057] 14  Vertical side wall  
     [0058] 15  Drilled hole  
     [0059] 16  Barrier