COMPASS

Abstract: The compass according to the invention comprises a compass top and two compass legs (1, 2) mounted rotatably in the compass top, the compass top comprising two top-halves (3, 4). Provided in each compass-top half is a bearing pivot (19) for respectively bearing a compass leg, as well as a counter-core (20) which, in the assembled state, engages in the bearing pivot of the corresponding compass-top half. A permanent and even radial frictional clamping is thus produced. At the same time, the counter-cores bring about a limitation to the opening of the compass due to corresponding in the compass legs.

Description: COMPASS The invention relates to a compass according to the preamble of Patent Claim 1. So-called single-journal compasses are known from DE-C 29 11 015 and GB-C 1,170,243. In these single-journal compasses having a compass top in which the compass legs rotate together about a pivot formed as a screw, the screw causes axial frictional clamping at the apex of the connected compass legs, in that, in interaction with a counter-nut or with a counter-thread, the friction surfaces of the legs are squeezed together. Both the previously known compasses require the use of relatively expensive metal screws. Additionally, the two previously known compasses do not have straight guiding of the compass top; the compass top thus assumes different angles relative to the drawing plane depending on the angle of opening of the compass legs. This lack of straight guiding makes use of the compass difficult since the compass top constantly has to be positioned during use. A drawing instrument, in particular a drawing compass or dividers or callipers, is known from DE-C 27 33 978. In this case, an axial frictional clamping is likewise produced by a large-area leg top and by a screw with a counter-nut. Furthermore, an additional punching plate made of steel is provided for the straight guiding of the compass top. The three parts mentioned, screw, counter-nut and punching plate, make the compass expensive and lead to complicated assembly of the individual parts of the compass. Apart from the three parts mentioned which consist of metal, the compass legs must also be made of metal since the compass legs are of narrow design; the use of plastic material for the compass legs is virtually ruled out since these would bend in a non-permissible manner during use. A compass is already known from DE-C 25 23 046, in which two tightening screws each form a pivot for each of the two compass arms . Compasses, whose top and legs are attached using a screw, are known from the following publications: DE-A 1411830, DE-C 243002, DD 280072, DE-A 4201854, DE-U 1863371, US Patent 4,858,326, DE-A 2922999. The use of screws for attaching the compass leg and the compass top firstly entails the disadvantage of the relatively high cost of the screws. Moreover, when using screws, the axial frictional clamping they cause can only be adjusted or readjusted with difficulty. Moreover, there is the risk that compasses with self-tapping screws without a counter-nut become overturned, thus losing the required frictional clamping and becoming unusable. Setting out from this prior art, the invention is based on the technical problem of providing a compass of simple construction which can be both manufactured and operated in a simple manner. This technical problem is solved by a compass as is defined in the patent claims. The compass according to the invention can be manufactured without the use of screws and counter-nuts or counter-threads. Readjustment of the frictional clamping during use of the compass is not required owing to its construction. In particular, in the compass according to the invention, an essentially radial frictional clamping is formed between the compass legs and the compass top, while an axial component of the frictional clamping formed is of only subsidiary importance. In particular, the bearing pivots of the compass top are of slightly conical design so that, when the compass legs are mounted on the compass top, the bearing pivots engage with slight press- fitting in the corresponding bores of the compass legs. The conical design of the bearing pivots also facilitates the manufacture of the compass top by the injection moulding method. According to the invention, (first) spreading cores can be introduced into the counter-cores which engage in the bearing pivots and additionally spread the latter apart in the end position of the bearing pivots in the counter-cores so that the connection is non-releasable. A further advantageous embodiment is characterized in that, in the region of the compass-top half, the width of each compass leg is such that it essentially corresponds to the width of the compass- top half. Bending of the compass legs is avoided or reduced due to this relatively wide design of the legs. According to a further advantageous embodiment, the compass leg has, in the region of the respective counter-core, an opening which is shaped such that it defines the angular adjustment of the compass leg. According to a further advantageous embodiment, each compass leg has a toothing in the region of an opening which receives the bearing pivot, the teeth of the two compass legs meshing with one another and, in this way, guide the compass top in a straight manner. According to a further advantageous embodiment of the invention, corresponding centring elements are provided in the compass-top half and in the compass legs. As a result, lateral bending which occure during loading of the leg is absorbed. According to a further advantageous embodiment of the invention, the tightening tongs which receive a compass point or a writing element are opened laterally so that the compass point and the writing element can be introduced into the tightening tongs or removed from the tightening tongs in a simple manner. In this regard, a tubular piece can also be provided, which is received by the tightening tongs and which, in turn, receives a writing element or a point. This considerably extends the range of application of the compass; the compass can also be used as dividers or callipers. Further advantageous embodiments of the invention are characterized in the further claims. Exemplary embodiments of the invention are now described in greater detail with reference to the following drawings, in which: Figure 1 shows the front view of an exemplary embodiment of a compass in the closed state according to the present invention; Figure 2 shows the side view of the same compass; Figure 3 shows a horizontal section along the line A-A in Figure 1; Figure 4 shows a front view of the same compass in the maximum opened state; Figure 5 shows a view of the outer side of a compass leg; Figure 6 shows a side view with a partial section along the line A-A in figure 7; Figure 7 shows a view of the inner side of the compass leg according to Figure 5; Figure 8 shows a horizontal longitudinal section along the line B-B in Figure 5; Figure 9 shows a partial section along the line C-C in Figure 5; Figure 10 shows a view of an insertion part which may be a constituent part of a compass leg according to Figure 5; Figure 11 shows the side view of the insertion part according to Figure 10; Figure 12 shows a cross-section along the line D-D in Figure 10; Figure 13 shows a section along the line B-B of the compass-top halves shown in Figure 14 and the upper region of the compass legs; Figure 14 shows a cross-section along the line A-A in Figure 13; Figure 15 shows a horizontal section along the line C-C in Figure 13; Figure 16 shows a horizontal section along the line D-D in Figure 13; Figure 17 shows a section similar to Figure 13, the compass legs being shown in the maximum opened state; Figure 18 shows an extract enlargement of a detail of Figure 14; Figure 19 shows a perspective view which shows the complete assembly of the two compass-top halves with the compass legs, a first leg already having been fitted onto a compass-top half, and another leg being shown in a position prior to its assembly on the other compass-top half; Figure 20 shows a partial section of tightening tongs with a graphite insert of a compass leg according to the present invention; Figure 21 shows a section along the line A-A in Figure 20; Figure 22 shows a partial section of the tightening tongs with a compass point of a compass leg according to the present invention; Figure 23 shows a section along the line B-B in Figure 22; Figure 24 shows a partial section of tightening tongs of a compass leg with a compass point held in a tubular piece according to the present invention; and Figure 25 shows a section along the line C-C in Figure 24. As can be seen from Figures 1 to 4, the compass comprises the following main constituent parts: a compass top which is composed of two halves 3 and 4, and a first and a second compass leg 1 and 2 which are both attached in the compass top and are mounted rotatably. A gripping portion 5 is formed on the compass top. The legs are made, in particular, of plastic material and can be reinforced with a profiled insertion part 6 made of steel sheet. Located at the lower end of the first compass leg 1, that is to say in the region of the foot, are tightening tongs 25 (Figures 5, 6, 7 and 9) and a threaded sleeve 7 (Figures 1, 2), which together clamp, for example, a graphite insert 8 or another type of writing element such as, for example, a ball-point pen insert, an ink pen or felt pen, etc. Likewise located at the lower end of the second compass leg 2 are tightening tongs 29 (Figure 22) and a threaded sleeve 9, which together hold, for example, a compass point 10. Figure 19 shows the design of the compass-top halves 3 and 4 and of the two compass legs 1 and 2 in their top region as well as their assembly. The compass top comprises two compass-top halves 3 and 4. 96/22889 c A bearing pivot 19', 19 (concealed in Figure 19) and a counter-core 20', 20 are provided in each compass-top half 3, 4. Provision may be made for either a bearing pivot or a counter-core to be present in each of the two compass-top halves. With the compass legs which are arranged on the same bearing pivot, these compass-top halves designed in this manner form a single-journal compass. These compass legs do not have teeth 16, 16' which are described below in conjunction with the compass legs of a two- journal compass. The bearing pivots 19', 19 engage in the counter-cores 20', 20 of the respective other compass leg, preferably with press-fitting, and, in the assembled state, form a virtually non-releasable connection. The two legs 1 and 2 are arranged relative to one another as shown in Figure 15. In this case, they come into engagement with their toothing 16 and 16' . The toothing, which has yet to be described, serves for the straight guiding of the compass top. The compass-top halves 3 and 4 are mutually fitted together for assembly. In this case, the bearing pivot 19 of the compass-top half 4 is fitted through an opening (bore) 13 in the upper part of the leg 1 and pressed onto the counter-core 20'of the opposite compass-top half 3. In this position, the counter-core 20 of the compass-top half 4 is passed through an opening 14 in the leg 1 (Figure 19) . This opening is shaped such that it defines the angular adjustment of the respective leg. The bearing pivot 19'of the compass-top half 3 is likewise fitted through the bore 13' in the upper section of the leg 2 and pressed onto the counter-core 20 of the opposite compass-top half 4. The counter-core 20' is passed through an opening 14' in the leg 2. An additional (first) spreading core 21 (Figure 18), which is located in the internal bore of the bearing pivot 19 of the compass-top half 4, enters into the counter-core 20' of the compass-top half 3 and spreads it apart to form a non-releasable connection of the two compass-top halves 3 and 4. A further (first) spreading core 21' in the bearing pivot 19' also brings about the connection of the two compass-top halves in the same manner. Instead of the spreading cores or even in addition to the spreading cores, provision may be made for the counter-core and bearing pivot to be bonded or welded to one another, for example, thus forming a non-releasable connection. Owing to the design of the bearing pivot, the counter-core and the spreading core, as described, the two legs 1 and 2 are held so as to be movable without play between the two compass-top halves 3 and 4. An axial frictional clamping is produced between the outer surfaces of the legs and the inner surfaces of the compass-top halves, the absence of play being important for reducing the bending of the legs in the working position. The axial frictional clamping occurring, however, is of secondary importance for the function of the compass according to the invention. Of primary importance in the compass according to the invention is a radial frictional clamping, as will also be described below. The inner and outer surfaces of the bearing pivots 19, 19', the bores 13, 13' in the legs 1 and 2 and the counter-cores 20, 20' are of slightly conical design. During manufacture, this allows, on the one hand, reliable demoulding of the parts from the injection mould and, on the other hand, assembly which is easy to automate, there being no problem concerning the tolerances required for injection moulding to produce the different diameters of the plug connection. Furthermore, by this design of the said parts, press-fitting between the bearing pivot and the counter-core and slight press- fitting between the bearing pivot and the compass leg are formed. In the case of the press-fitting between the bearing pivot 19 and the counter-core 20' , a first tension is built up between the inside wall of the bearing pivot 19 and the outside wall of the counter-core 20' (depicted by the pair of arrows on the right in Figure 18) and a second tension is built up between the outside wall of the spreading core 21 and the inside wall of the counter- core 20' (depicted by the pair of arrows on the left in Figure 18) . The two tensions are superimposed and act on the wall of the bore 13 of the leg 1. On these surfaces, a particularly permanent and even radial frictional clamping is thus produced, which guarantees secure working an all angular settings of the compass. In the compass according to the invention, a permanent, radial frictional clamping is thus formed by elements which, on the one hand, connect the compass-top halves to one another and which, on the other hand, hold the compass legs in the compass-top halves. When preferably using self-lubricating plastic materials for the compass-top halves, at least for the outside walls of the bearing pivots on the one hand and/or the inside wall of the bores 13, 13' of the compass legs on the other hand, premature wear is avoided and good handling and a long service life are thus guaranteed. An exemplary embodiment of the compass leg 1 with a plastic- sheathed, for example, metal insertion part 6 is illustrated, in particular, in Figures 5 to 12. The insertion part 6 (Figures 10 to 12) is profiled (profile 11) and thus gives the plastic legs a particular strength. Insertion parts 6 are provided, in particular, in the region of the leg top and/or in the region between the leg top and the foot. Connection holes 12 in the insertion part 6 receive the plastic material and thus additionally increase the rigidity of the legs. The bore 13 in the compass leg 1, as already described, is provided for receiving a bearing pivot 19, while an opening 14 which is, for example, partially circular (whose associated centre-point forms the bearing pivot 19) serves to guide a counter-core 20 and thus defines the angular adjustment of the leg. The inside wall of the bore 13 can be of conical design, as already described. Figure 17 shows that, in the case of maximum opening of the compass, the counter-core 20 strikes against the opening 14 and thus prevents further opening of the leg 1 and, in interaction with the teeth 16, 16', also of the leg 2. A secure working range of the compass is guaranteed by this simple and, at the same time, sturdy arrangement. The compass legs 1 and 2 illustrated in the figures have, on the inner side and outer side, a plurality of cutouts 15 which are caused by cores of the injection moulds. These cores hold the insertion part 6 centrally during sheathing and also allow it to become partially visible so that the visual effect of the metal remains intact. On the inner side of the upper end, the leg 1 is fitted with a projecting toothing 16 (Figure 13) and, on the outer side of the upper end, with a centring projection 17 (Figure 14) which engages in a corresponding depression 18 (Figure 18) in the top-half 4 (Figures 13 to 18). The centring projection 17 of the leg 1, which projection is passed into the corresponding depression 18 of the compass-top half 4, prevents bending of the bearing pivot 19 and of the corresponding counter-core 20' since lateral bending of the centring projection 17 occurring during loading of the leg 1 is absorbed. It is true in general that corresponding centring elements are provided in the compass-top halves and in the compass legs, which elements prevent bending of the legs. In particular, the centring elements in the compass-top halves are designed as depressions 18, 18' and the centring elements in the compass legs are designed as centring projections 17, 17' . The depressions and centring projections are of circular design. In order to avoid or reduce bending of the compass legs, the legs are designed to be relatively wide, it being possible for the width of the legs to correspond in their upper section to the width of the compass top. In order to reinforce the connection of the two compass-top halves, two further attachments are provided, as illustrated in Figures 13, 14, 16 and 19. These are, for example, journals, in particular hollow journals 22, 22' and receiving elements 23, 23' for the journals 22, 22' (Figures 16, 19) . The hollow journal 22' of the compass-top half 3 is pressed into the corresponding receiving element (bore) 23 of the compass-top half 4. Additionally, a second spreading core 24 of the compass-top half 4 is inserted into the inner bore of the hollow journal 22', the second spreading core 24 spreading the journal 22' apart to form a non-releasable connection. The journal 22, a bore 23' and a second spreading core 24' interact in an analogous manner (Figure 16). As illustrated in Figures 5 to 9, tightening tongs 25 with a slot 26 for receiving, for example, a graphite insert 8 are located in the region of the foot,that is to say at the lower end of the leg 1. The tightening tongs 25 are arranged so as to be slightly sloping relative to the leg. This results in a setting angle 27 of about 53° at the maximum opening of the compass. In total, reliable working throughout the entire working range of the compass is guaranteed by this arrangement (Figure 4). Figures 20, 21 show that the tightening tongs 25 are open on one side due to a longitudinal groove 28. A section of the open longitudinal groove is illustrated in Figure 9. In conjuction with the threaded sleeve 7 which, when screwed closed, closes the tightening tongs 25 which have a slot 26, the graphite insert 8 is clamped. The lateral opening in the tightening tongs has the advantage that the user of the compass has easy access, for example when exchanging a broken graphite insert. This is not the case in the otherwise customary tightening tongs which have blind bores and are closed continuously at the side. The front bore (= bore which is disposed downwards during use of the compass) of the threaded sleeve 7 centres the graphite insert when the tightening tongs 25 are closed. The opening width of the longitudinal groove 28 is at least equal to the outside diameter of the graphite insert 8 or the writing element. The tightening tongs 29 for the compass point 10 shown in Figures 22 and 23 likewise has an open longitudinal groove 30 and a slot 31 which, together with the threaded sleeve 9, clamps the compass point 10 when screwed closed and holds it centrally. Moreover, the arrangement of the open longitudinal grooves 28 and 30 also has the important advantage, in terms of manufacture, of a considerable simplification of the injection mould for the legs 1 and 2 since no complicated lateral slide constructions are necessary. Owing to the fact that, as is otherwise customary, the compass point does not have to be inserted into the extension of the compass leg from the front, but can be inserted laterally via the open longitudinal groove, it is possible to use a commercially available pin with a head as the compass point. The arrangement of the tightening tongs and the threaded sleeve provided according to the invention allows a short projection over the tip both of the graphite insert and of the compass point. In the case of the graphite insert, this leads to a lesser risk of breakage and, in the case of the compass point, a considerably reduced risk of injury. The arrangements of the tightening tongs illustrated in Figures 24 and 25 is identical to that shown in Figures 20 and 21. Instead of the graphite insert, a pin with a tubular piece 32 is used, the tubular piece having the same outside diameter as the graphite insert. The compass can thus also be used as dividers or callipers. Provision may also be made for the tightening tongs to have an inside diameter which is larger than the outside diameter of customary graphite inserts or customary compass points. The inside diameter of the tightening tongs can be designed for tubular pieces of larger outside diameter, the said tubular pieces receiving compass tips or writing elements (graphite inserts, ballpoint pen inserts, etc. ) . The legs can be produced, for example, from a metal alloy based on zinc (e.g. dye-casting zinc alloy "Zamak") which is suitable for dye casting. The compass according to the invention can also be designed with identical teeth and tightening tongs on both legs, thus enabling the production process to be less expensive. In the case of an identical design of the legs, the two bearing pivots in the compass-top halves are offset in such a way that two sets of teeth engage in one another. Items: 1 First leg 2 Second leg 3 First compass-top half 4 Second compass-top half 5 Gripping portion on compass top 6 Insertion part 7 Threaded sleeve in leg 1 8 Graphite insert/writing element 9 Threaded sleeve in leg 2 10 Compass point 11 Profile 12 Connection holes 13, 13' First opening 14, 14' Second opening 15 Cutouts 16, 16' Toothing 17, 17' Centring projection 18, 18' Depression 19, 19' Bearing pivot 20, 20' Counter-core 21, 21' First spreading core 22, 22' Hollow journal 23, 23' Bore 24, 24' Second spreading core 25 Tightening tongs for graphite insert/writing element 26 Slot in leg 1 27 Setting angle 28 Longitudinal groove in leg 1 29 Tightening tongs for compass point 30 Longitudinal groove in leg 2 31 Slot in leg 2 32 Tubular piece

Claims: CLAIMS 1. - Compas comprising a compass top and two compass legs (1, 2)mounted rotably in the compass top, the compass top comprising a first and a second compass-top half (3, 4), characterized in that a bearing pivot (19, 19') for bearing in each case a compass leg (1, 2) and a counter-core (20, 20') is provided im each case in the first and in the second compass-top half (3, 4), in that the counter-core of the first compass-top half (3) engages in the assembled state in the bearing pivot of the second compass-top half (4) and is connected non-releasably to this bearing pivot, and in that the counter-core of the second compass- top half (4) engagesin the assembled state in the bearing pivot of the first compass-top half (3) and is connected non-releasably to this bearing pivot. 2. - Compass comprising a compass top and two compass legs (1, 2) mounted rotably in the compass top, the compass top comprising a first and a second compass-top half (3, 4), characterized in that a bearing pivot for bearing the compass legs (1, 2) is provided in the first compass-top half (3), and in that a counter-core is provided in the second compass-top half (4), which counter-core engages in the assembled strate in the bearing pivot of the first compass-top half (3) and is connected non-releasably to this bearing pivot. 3. - Compass according to Claim 1 or 2, characterized in that the non-releasably connection is formed by a first spreading core (21, 21') introduced into the counter-core (20, 20') . 4. - Compass according to one of the preceding claims, characterized in that the counter-core (20, 20') and the bearing pivot (19, 19') are bonded or weldet to one another. 5. - Compass according to one of the preceding claims, characterized in that directly adjacent walls of the bearing pivots (19, 19') and of the respective counter-core are of correspondingly conical design. 6. - Compass according to one of the preceding claims, characterized in that, in the region of the compass-top half, the width of each compass leg is such that it essentially corresponds to the width of the compass-top half. 7. - Compass according to Claim 6, characterized in that the compass leg (1, 2) has, in the region of the counter-core (20, 20') an opening (14, 14') which is shaped such that it defines the angular adjustment of the compass leg (1, 2) . 8. - Compass according to one of the preceding claims, characterized in that each compass leg (1, 2) has a toothing (16, 16') in the region of an opening (13, 13') which receives the bearing pivot, the teeth of the two compass legs (1, 2) meshing with one another. 9. - Compass according to one of the preceding claims, characterized in that the opening (13, 13'), receiving the bearing pivot (19, 19*), in the compass leg (1, 2) consists of self- lubricating plastic material on its inside wall, and/or the bearing pivot (19, 19') consists of self-lubricating plastic material on its outside wall in the region of the opening (13, 13'). 10. - Compass according to one of the preceding claims, characterized in that corresponding centring elements are provided in the compass-top half and in the compass legs. 11. - Compass according to Claim 10, characterized in that a depression (18, 18') is provided in the compass-top half and a centering projection (17, 17') is provided respectively in the compass legs. 12. - Compass according to one of the preceding claims, characterized in that the compass-top halfes have further attachments (22, 22'). 13. - Compass according to Claim 12, characterized in that each compass-top half has a journal (22, 22') and a receiving element (23, 23') for the journal of the respective other compass- top half. 14. - Compass according to Claim 13, characterized in that a second spreading core (24, 24') can be introduced into an internal bore of the journal (22, 22') . 15. - Compass comprising two compass legs consisting of plastic material, characterized in that the compass legs furthermore have at least one metal part (6) in the region of the leg top and/or in the region between the leg top and the foot. 16. - Compass according to Claim 15, characterized in that the metal part (6) is designed as an insertion part. 17. - Compass according to Claim 16, characterized in that the insertion part has through-holes (12) for receiving the plastic material. 18. - Compass-top half for a compass according to one of the preceding claims. 19. - Compass leg for a compass according to one of Claim 1 to 17. 20. - Compass according to one of the preceding claims, having compass legs, tightening tongs (25, 29) for receiving a compass point or a writing element being arranged in the region of the foot, characterized in that, to receive the compass point (10) or the writing element (8), the tightening tongs (25, 29) have a longitudinal groove (28, 30) whose opening width is at least equal to the outside diameter of the compass point (10) or the writing element (8) . 21. - Compass according to Claim 20, characterized in that the compass point is formed by a commercially available pin. 22. - Tubular piece as an a receptacle in the foot of a compass according to one of the preceding claims, characterized in that the tubular piece (32) has an outside diameter which is equal to the outside diameter of a writing element which can be introduced into the foot or of a compass point which can be introduced into the foot. 23. - Tubular piece according to Claim 22, characterized in that the tubular piece (32) receives a compass point or a writing element. 24. - Tubular piece according to claim 23, characterized in that the compass point is formed by a commercially available pin.

Inventors: BUSCHLE RICHARD DIETER, BUSCHLE, RICHARD, DIETER
Applicants: BUSCHLE RICHARD DIETER, BUSCHLE, RICHARD, DIETER
Application year: 1996
Main classification: B43L9
IPC codes: B43L9