Abstract:
A carriage drawing machine having a horizontal carriage driven along a horizontal slide rail support and carrying a vertical slide rail support. The vertical slide rail support and the horizontal carriage are coupled and are mutually tensioned by means of an interlocking mechanism.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to carriage drawing machines and more particularly concerns interlocking mechanism to positively couple the vertical slide rail support to the horizontal carriage. 
     DISCUSSION OF THE PRIOR ART 
     With known carriage drawing machines, the vertical sliding carriage support is screwed and additionally glued together with a support frame. The latter extends over the drawing board. At its rear end it is pivotably mounted on the horizontal carriage. In this way, the drawing machine can be flipped up from the drawing board. This connection between the vertical slide rail support and the support frame is expensive to manufacture. Nevertheless, this connection is unavoidably loosened somewhat under constant use, thus considerably impairing the accuracy of the drawing. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to avoid the above stated disadvantage and to create a connection between the horizontal carriage and the vertical slide rail support which connection guarantees a permanent, absolutely rigid tensioning. 
     A horizontal carriage is driven along a horizontal slide rail support and carries a vertical slide rail support. An interlocking mechanism provides mutual tensioning between the vertical slide rail support and the horizontal carriage to provide a positive coupling therebetween. This tensioning by means of an interlocking mechanism creates a connection through the intermeshing of the two parts. This connection is so solid that it can certainly not loosen unintentionally during running use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The objects, advantages and features of this invention will be easily understood from the following description when read in conjunction with the accompanying drawing in which: 
     FIG. 1 is a partial top view of the carriage drawing machine of this invention mounted on a drawing board; 
     FIG. 2 is a partial sectional rear view of the support frame with the mounted vertical slide rail support taken along plane 2--2 of FIG. 1; 
     FIG. 3 is a top view of the support frame; 
     FIG. 4 is a fragmentary view of the rear side of the end piece of the vertical slide rail support; and 
     FIG. 5 is a is a fragmentary view showing the interlocked teeth 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference now to the drawing and more particularly to FIG. 1 thereof, there is shown the carriage drawing machine of this invention wherein a horizontal slide rail support 2 is connected with a drawing board 1. A horizontal carriage 3 is guided along the slide rail support 2 and a support frame 6 is pivotably mounted in lateral projections 5 of the horizontal carriage 3. A vertical slide rail support 4 for a vertical carriage 7 is affixed to the support frame 6. The carriage 7 carries a drawing head 8. 
     As is shown in FIG. 2, the vertical slide rail support 4 is formed with a hollow section. At the side facing the drawing board it has two brackets 9 with projections 10 extending inwardly. At the end edges of the brackets 9 in the area of the connection point with the support frame 6 is formed an interlock 11a in the form of teeth and grooves (see FIG. 4). The teeth of this interlock constrict from the fase of the tooth outward, whereby the flanks of each tooth enclose an angle of about 30° (FIG. 5). It has been determined that four interlocking teeth are sufficient to secure the connection. 
     The corresponding counter-interlock element is provided in a forwardly protruding arm 13 of the support frame 6 as shown in FIGS. 2 and 3. The support frame 6 is pivotably mounted in the horizontal carriage 3 and the end surfaces of the support arms 13 point outward. These end surfaces are stepped and include fitting surfaces 14(a), 14(b) and 14(c), and an outermost portion which contains the interlock 11b. Its function is to accept the projections 10 of the brackets 9 of the vertical slide rail support 4. Proceeding further inwardly, there follows another surface 14b (FIG. 2) which again protrudes somewhat. The stepped fitting surface is terminated by a protruding strip 14c which serves as a support for a bracket 16. The design of the interlock 11b on the support arms 13 corresponds to the interlock 11a on the vertical slide rail support 4. 
     Screws 15 serve for mutual tensioning and they engage the brackets 16 shown in FIG. 2. Brackets 16 extend behind the projections 10 on vertical slide rail support 4. When the screws 15 are pulled tight, the interlocks 11a and 11b respectively are mutually tensioned on the slide rail support 4 and on the support frame 6, whereby the size of the teeth is mutually coordinated so that, even after a tight tensioning, there still remains some distance between the front surface of each tooth of one interlock and the corresponding tooth base of the other interlock. 
     In view of the above description, it is likely that modifications and improvements will occur to those skilled in the art which are within the scope of this invention.