US3479763A

US3479763A - Assembly kit having dovetail connection with reduced contact area

Info

Publication number: US3479763A
Application number: US514165A
Authority: US
Inventors: Artur Fischer
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-11-13
Filing date: 1965-11-08
Publication date: 1969-11-25
Anticipated expiration: 1986-11-25
Also published as: FI43278B; BE671742A; CH438122A; IL24566A; NL6513348A; CS156403B2; NO118425B; SE327937B

Description

Nov. 25. 1969 A. FISCHER 3,479,763

ASSEMBLY KIT HAVING DOVETAIL CONNECTION WITH REDUCED CONTACT AREA Filed Nov. 8, 1965 2 Sheets-Sheet 1 Fig. 4

I N VEN TOR.

ARTUR FISCHER BY Nov. 25, 1969 Filed NOV. 3, 1965 A. FISCHER ASSEMBLY KIT HAVING DOVETAIL CONNECTION WITH REDUCED CONTACT AREA 2 Sheets-Sheet 2 IN V EN TOR.

ARTUR FISCHER BY United States Patent US. Cl. 4625 7 Claims ABSTRACT OF TIE DISCLOSURE In a toy building kit a socket member has a first exposed surface which is provided with a groove of undercut configuration having an outer portion adjacent to the exposed surface and an inner portion bounded by an interior surface and increasing in width in a direction inwardly away from the outer portion. A plug member is provided having a second exposed surface from which a connecting projection extends which is adapted to be received in the groove. The projection includes a neck por tion which is to be received in the outer portion of the groove and a head which is to be slidably received in the inner portion of the groove and which has a crosssectional area smaller than that of the inner portion so that the projection will be in engagement with the interior surface only in the region adjacent the outer portion of the groove.

The present invention relates to an assembly kit. More specifically, the invention relates to a kit of the type with which various structures can be assembled from building blocks provided in the kit. Still more specifically, the invention relates to a kit of the above type in which the building blocks are connected together by way of connecting formations respectively provided on the building blocks themselves or in the form of separate members.

Assembly kits utilizing building blocks of the type mentioned above are known. There are, for example, disclosed in my copending application Ser. No. 492,646, filed on Oct. 4, 1965, building blocks from which models and toy structures may be assembled. In such assembly kits the basic building blocks are provided with grooves which extend inwardly of one or more exposed faces of the blocks and Whose cross-sectional area increases in the direction inwardly away from such exposed faces. Thus, at the surface the area is narrower than inwardly thereof, whereby a slot is defined in the surface. Heads or connecting members of a configuration substantially similar to the cross-sectional area of the grooves are provided on other blocks or in the form of separate connecting members, and these connecting members or heads are receivable in the grooves. They are joined to necks which are only as wide or just slightly wider than the slots and which extend outwardly through such slots so as to connect additional elements to the first building block. 7

This system of connecting together the blocks has been found to be highly successful since it requires no manipulations, requiring manual dexterity, such as the use of screws which frequently are undesirable, particularly if the kit is to be used by a child. However, it has been found that a difiiculty does exist with this system in that the manufacturer is frequently unable to maintain the relatively close tolerances which are required if the connecting means are to be received and manipulated with ease within the grooves. This is the case regardless of whether the blocks and the connecting means are provided, as is preferred, from a plastic or from any other material. If the fit of the connecting means in the grooves is too tight, then adjustment of the connecting means relative to the building blocks in which the respective groove 3,479,763 Patented Nov. 25, 1969 is provided, becomes too difiicult. Conversely, if the fit is too loose, then the connection is not proper and is likely to come apart. It will be understood that in a construction such as that set forth in the above-mentioned copending application it is desirable that the connections established be firm, but yet that the individual elements, such as blocks and connecting means, he movable relative to each other with reasonable ease.

Accordingly, it is a general object of the present invention to overcome these disadvantages arising from such manufacturing difficulties.

A more specific object of the present invention is to provide a connecting system as has been outlined above, in which allowance is made for the almost inevitable tolerance variations which occur during manufacturing of building blocks and connecting means, so that tight connections are achieved with the above system while yet the respective members are movable relative to one another with reasonable case.

In accordance with one feature of my invention I provide, in an assembly kit, a combination of a socket member which has an exposed surface provided with a groove. This groove has a portion adjacent to the exposed surface and increases in width in a direction away from said surface. I further provide a plug member having a connecting means, including a connecting portion which slidably extends into the groove so as to at least partially fill the same, and a neck portion on the connecting portion and received in said portion of the groove. Finally, I provide means for enhancing the flexibility of that part of the socket member which surrounds the groove so that, upon insertion of the connecting means into the groove, the surrounding part of the socket member can yield to pressure exerted by the connecting means.

The novel features which are considered as charac teristic'for the invention are set forth in particular in the appended claims. The invention itself however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which,

FIG. 1 is an end view of a building block embodying the invention in one example;

FIG. 2 shows a modified embodiment of the invention in a partial end view;

FIG. 3 shows yet a further modification of this invention in a view similar to that of FIG. 2;

FIG. 4 is a top-plan view of a structural member embodying the invention;

FIG. 5 is an end view, partly in section, of yet a further embodiment of the invention;

FIGS. 6-8 show a building block embodying a modification of the invention in a top-plan view, a side view and a bottom view, and

FIG. 9 shows the components of FIG. 8 separated for clarity of explanation.

Turning now to the drawing, and firstly to FIG. 1 thereof, it will be seen that I have provided a building block such as disclosed in my above-mentioned copending application. This building block is designated with reference numeral 1. It is provided with the grooves 2 which are narrow adjacent the exposed surfaces of the building block and widen in their cross-sectional area inwardly of these exposed surfaces. One end face of the building block shown in FIG. 1 is provided with a cylindrical connecting member or head 3 which is joined to the building block by means of a narrow neck portion 15a (see FIG. 5). The other end face may also be provided with a connecting member or head 3, but I prefer to provide it instead with crossed grooves 2 (not shown).

In order to enhance the flexibility of that part of the building block, which latter may also be considered a member, which surrounds the grooves, so that upon insertion of the head 3 into the grooves 2 the surrounding part of the socket member can yield to the pressure exerted by the head 3, I provide in the embodiment shown in FIG. 1 a slot 4 which extends parallel to the respective groove 2 with slight spacing therefrom. It will be obvious that this will make the lip portions 1a, that is the portions which define the slot leading from the wider portion of the grooves 2 to the exposed surfaces of the socket member 1, more flexible and will enable them to yield to pressure when the heads 3 of adjoining building blocks or socket members 1 are inserted into the grooves 2. Of course, it is possible to use the slots 4 additionally for the purpose of disposing thin plate-like members therein and thereby connecting them to the respective socket members 1. Such plate-like members may be small pieces of clear plastic which may serve as windows in a structure built from the present assembly kit.

FIG. 2 shows a modification of the embodiment in FIG. 1. The grooves 2a are not of substantially cylindrical cross section as in FIG. 1, but are rather of the dove-tail type. The resiliency-promoting slots are indicated with reference numeral 4a and extend again parallel to the grooves 2a; furthermore, they are slanted at the same angle at which the respective side walls of the grooves 2a are slanted.

Turning to FIG. 3, it will be seen that the grooves provided in the socket member 5 are designated with reference numeral 212 and are of substantially rectangular cross-section. The lip portions, that is the portions which define the area of narrow cross-section adjacent the exposed surface of the socket member 5, are formed by projections 5a which project from either side of the grooves 2b towards the center, but do not meet. Again, slots 4 extend parallel to the grooves 2b with slight spacing therefrom. It will be seen that in the embodiments of FIGS. 2 and 3 such slots extend on either side of grooves 2a and 2b; however, this is of course not necessary and it is possible to provide slots only on one side as is clearly indicated in the embodiment of FIG. 1. FIG. 4 is a topplan view of the embodiment shown in FIG. 3 and it will be seen from this embodiment that projections 5a are elongated, but are shorter than the grooves 2b. Thus, the projections 5a terminate short of the respective ends of the grooves 2b by a distance which corresponds to the axial length of the head or connecting member 3, so that in this Way the connecting member 3 may be inserted transversely of the axial extension of the grooves 2b if for some reason an axial insertion is impossible or not desired. The socket member 5 is further provided with a bore, as shown in FIG. 4, which is designated with reference numeral 6 and is preferably centrally located. The bore 6 receives an auxiliary rnmeber, such as a cylindrical rod which may serve as an axle, a pivot point or for similar purposes.

The embodiments described with reference to the preceding figures have dealt with providing a firm reception of the connecting member 3 in the

respective grooves

2, 2a or 2b. At the same time they have been intended to prevent binding of this head or connecting member 3 in such grooves. However, to some extent the movement of the head 3 in the respective groove will still be relatively stiif and this is as it should be under ordinary circumstances, to prevent separation of the members from which a structure has been built. The exception to this occurs if the kit is to be used by children for whom this stiffness might present certain problems. To overcome it in such cases, that is to make it still easier to insert the head into the respective groove and to move it therein, there is provided in the embodiment of FIG. 5 an arrangement, whereby the cross-section of the head will not be entirely complementary to the cross-section of the groove. In other words, the head will be so shaped that it will engage the surrounding wall of the groove only over part of its own surface, while the rest is spaced from the wall. At the same time, some of the tightness which is relinquished by this arrangement, is restored by making the neck 15a just slightly wider than the slot defined by the lips 12a. This is shown in FIG. 5 where the socket member is designated with reference numeral 11 and in FIG. 9 where the width a of the neck exceeds the width b of the slot between the lips bounding the latter. This socket member 11 is provided with a groove 12 similar to the groove 2 shown in the embodiment of FIG. 1. It will be understood, of course, that this groove could also have crosssections different from the areas shown. At the point at which the groove communicates with an exposed surface of member 11, there are provided lips 12a on either side of the slot. These lips are made more elastic by the provision of at least one additional slot 13 which extends parallel to the groove 12 'as described with reference to the embodiment of FIG. 1.

A second socket member or building block 14 is provided with a head or conecting member 15 of complementary-in this case circularcross-section which is secured to the socket member 14 by means of a narrow neck 15a. The cylindrical connecting member 15 is not quite complementary to the cross-section of the groove 12 so that, when it is received, its longitudinal axis is slightly offset from the longitudinal axis of groove 12 in the direction toward the lips 12a. Thus, the connecting member 15 will engage the wall surrounding groove 12 only over part of its surface inwardly adjacent the lips 12a. The neck 15a is slightly wider than the spacing of the lips 12a so that there is a resilient deflection of the surrounding material of member 11 which is made possible by provision of the slot 13. It will be understood that the fact that the connecting member 15 does not engage the surrounding wall of groove 12 over its entire surface area, makes it much more easy to insert and slide the head or connecting member 15 within the groove 12.

At the same time, it will be clear that, if the neck 15a is slightly shorter than the depth of the lips 12a, as seen looking into the groove 12 transversely of its longitudinal axis, when the engagement of the surface portions of the head 15 with the Wall directly inwardly of the lips 12a will also serve to bias the member on which the head 15 is provided against the exposed surface of the socket member 11, which again assures a tight connection between the members.

The embodiment of FIGS. 68 shows that it is also possible to dispense with the parallel slot 13 and to provide instead a slot which may be formed at the bottom of groove 12 and extends inwardly toward the center of the respective member 11. This is also shown in FIG. 9, where the dimension 0 of the neck is slightly shorter than the dimension d. In the embodiment of FIGS. 6-8 the socket member 11 is provided with the usual grooves 12. one in each longitudinal surface, and is thus divided into four segments 11a. The provision of the slots 13' at the bottom of the respective grooves 12 imparts increased flexibility to the respective segments 11a. The effect is the same as with the provision of the grooves 13 along and parallel to the grooves 12 as shown in the other figures.

The members in accordance with the invention are preferably provided from a plastic material, of which polyamide has been found particularlysuitable because of its toughness and resiliency. However, other materials may be used.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of assembly kits diifering from the types described above.

While the invention has been illustrated and described as embodied in assembly kits, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an assembly kit, the combination of a socket member having a first exposed surface provided with a groove, said groove having an outer portion adjacent to said exposed surface and an inner portion bounded by an interior surface and increasing in width in a direction inwardly away from said first surface and from said outer portion; and a plug member having a second exposed surface provided with a projecting connecting means adapted to be received in said groove, said connecting means including a neck portion adapted to be received in said outer portion of said groove and a connecting portion adapted to slidably extend into said inner portion of said groove, said neck portion having a length which is less than the depth of said outer portion of said groove so that when said connecting means is received in said groove said first and second surfaces will be biased against one another, and said conecting portions of said connecting means having a cross-sectional area smaller than that of said inner portion of said groove and a height which is smaller than the depth of said inner portion so that when said connecting means is received in said groove said connecting portion frictionally engages said interior surface of said inner portion only in the region adjacent to said outer portion while being spaced from the remainder of said interior surface of said inner portion, said connecting means being operative for firmly connecting said members against separation in a direction transversely of the elongation of said groove by the frictional engagement of said members in the region adjacent to said outer portion of said groove, but for admitting of sliding displacement of said members relative to one another longitudinally of said groove due to their spacing along said remainder of said interior surface of said inner portion of said groove, with said first and second surfaces remaining in abutment with each other.

2. In an assembly kit as defined in claim 1; said socket member further comprising slot means extending adjacent to said groove for enhancing the flexibility of said socket member in the region of said groove.

3. An assembly kit as defined in claim 2, wherein said slot means extends laterally of said groove,

4. An assembly kit as defined in claim 2, wherein said slot means extends parallel to said groove.

5. An assembly kit as defined in claim 2, wherein said slot means is provided in the bottom of said groove and extends inwardly into the socket member.

6. An assembly kit as defined in claim 1, 'wherein at least one of said members is made from synthetic plastic material.

7. An assembly kit as defined in claim 1, wherein said neck portion is wider than said outer portion of the groove so that, when said connecting means is inserted into said groove, said neck portion will tend to enlarge the cross-sectional area of said outer portion of the groove.

References Cited UNITED STATES PATENTS 1,092,591 4/1914 Pajeau 4616 1,863,995 6/1932 Ponstingl 4625 X 1,985,992 1/1935 Hayman 4626 2,493,285 1/1950 Granat 63--15.3 2,662,335 12/ 1953 Oalverley 4629 3,032,919 5/ 1962 Amsler 4626 3,154,281 10/1964 Frank.

FOREIGN PATENTS 240,361 8/ 1962 Australia.

883,574 7/ 1953 Germany.

332,469 11/ 1935 Italy.

586,630 12/1958 Italy.

F. BARRY SHAY, Primary Examiner