US1394137A - Composite-joint construction - Google Patents

Description

UNITED STATES ROBERT S. BLAIR, OF SOUND BEACH, CONNECTICUT.

COMPOSITE-JOINT CONSTRUCTION.

Specification or' Letters Patent.

Patented Oct. 18, 1921.

Application led. December 23, 1915. Serial No. 68,339.

To @ZZ wwm t may concern Be it known that I, ROBERT S. BLAIR, a citizen of the United States, and resident of Sound Beach, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Composite- Joint Construction, of which the following is a specication.

This invention relates to jointvconstruction. One of the objects thereof is to provide a strong, rigid, practical joint which shall be durable under varying conditions of use. Another object is to provide joint construction of the above type in which the parts are readily assembled or taken apart. Another object is to provide a practical and convenient art for making a joint of the above type. Other objects will be obvious or pointed out'hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts and in the several steps and relation and order of such steps, all of which will be exemplified in the matter hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of the various possible embodiments of the mechanical features of the invention- Figure l is a side elevation of a member having a tenon formed thereon.

Fig. 2 is a longitudinal section through a portion of a member having a mortise adapted to receive a tenon of the above form.

Fig. 3 is a similar section taken through a completed joint, substantially along theine B-B of Fig. 5. Y

Fig. 4 is a similar view taken through the same joint along theline C-C of Fig. 5.

Fig. 5 is a sectional view taken along the line A-A of Fig. 3.

Fig. 6 is a sectional view on a smaller scale showing one of the steps in the art of forming a joint of this nature.

Similar reference characters 'refer to similarparts throughout the several views of the drawing.

Referring now to Fig. 1 of the drawing there is shown a member 1 provided with a tenon 2, this member being preferably of wood, and it may here be noted that the term wood is used in a broad sense to denote any organic, fibrous material. The tenon 2 is provided with the grooves 3, 4 and 5 with grooves 8, 9, and 10, although each of which extends entirely about the tenon, that is it traverses its entire circumference in a plane transverse thereof. These grooves are preferably shaped as shown with a more abrupt lower face 7. The grooves moreover increase in depth and width toward the lower end of the tenon, that is, the groove 4 is larger than the groove 3 and the groove 5 larger than the groove 4, in the preferred embodiment of this invention. The various groves are connected with one another by the longitudinal grooves 8 and groove 5 is connected by the longitudinal groove 9 with the end of the tenon. In like Vmanner the groove 3 is connected by a the memgroove 10 with the shoulder 11 on ber l.

It is to be understood that the longitudinal grooves 8, 9, and 10 are preferably duplicated on each face of the tenon as indicated by the dotted lines 12.

In Fig. 2 of the drawing is shown the remaining member 13 of the joint. This member is provided'with a mortise 14 and it is to be understood that the terms mortise and tenon areused in their usual broad sense. The walls of the mortise 14 are preferably provided with grooves l5, 16, and 17 which are so positioned as to register respectively with'the grooves 3, 4, and 5 and are similar in size and shape except that each of these mortise grooves has its most abruptly inclined face 18 at the upper side and its less inclined face 19 beneath or toward the bottom of the mortise. The walls of the niortise are also preferably provided with longitudinal grooves 2O registering these are not essential, if the grooves of the tenon are properly formed and disposed. There '1s provided at the bottom or end wall of the mortise 14 a transverse groove 21 which leads to a recess 22 each of the side walls of vwhich are undercut.

t may also be noted that there is provided at the lower end of the tenon 2 an undercut recess 28 positioned` to register with the recess 22 when the parts are assembled.

The following method is preferably employedin assembling the joint. The mem- Vbers are preferably first heated up to a pointv just below their scorching point and it may be noted by the latter term is meant that temperature at which the surface of the wood is softened or otherwise injured by heat.

Of course in this heating of the wood care should be taken that the exterior surface of the parts are not heated to such an extent as to injure their finish. With the members thus heated there is poured into the mortise in melted condition a metallic alloy. This alloy should be of such nature as to flow readily and completely at a point below the scorching point of the wood and, for example, a suitable alloy may be made of cadmium l part, tin 1 part and bismuth 2 parts. This alloy is not only melted but is preferably raised to a temperature materially above its melting point and then a small quantity introduced into the heated mortise'14.

The quantity of the material thus introduced is not more than a fraction of the total depth of the inortise, and depends on the volume of the spaces which are to be filled thereby, as hereinafter described, in the coinpleted joint.

As the tenon is forced downwardly into this molten metal, the latter is displaced upwardly and fiows readily through the several grooves 8, 9 and 10 and the registering parts in the mortise 14 until the tenon is forced home. The metal fills all of the recesses between the grooves 3, 4 and 5 and the registering grooves in the mortise, and also fills the spaces 22 and 23. The excess of metal, if there be any, may pass off between tlie shoulder 11 and the opposite portion of the member 13 and the parts are preferably so formed as to provide a slight crevice 24 within which a film of metal may be formed. This crevice may be made by slightly undercutting the shoulder.

In the above vaction it is to be noted that the heating of the wood before the metal is brought in contact therewith tends to cause the metal to enter into the minute pores of the wood and thus impregnate the portion of the wood adjacent the metal and better adapt it to withstand pressure. To achieve the latter results properly the metal should be superheated, that is heated above its meltino` point, so that it will still remain fluid if it be slightly cooled as it ends to enter into the pores of the wood.

In the above process the metal is forced into every minute crevice between the surface of the tenon and the opposite surface of the mortise, and an eiiicient joint is thus assured. It may here be noted that the term forced as used herein in connection with the fluid metal is employed in a broad sense to denote the application of a positive force and distinguish from the ordinary action of gravity, and it may also be noted that this force may be attained in other ways than by displacing the metal, as the latter may be forcibly injected in fluid form through a suitable small opening with a vent, or even atmospheric pressure may be utilized by suction of the air from the interstices be tween the tenon and mortise with the parts in assembled condition. There are however certain advantages inherent in the method first above described, although certain broad features of this invention may be otherwise carried on as herein indicated. l

After the joint is permitted to cool it takes the form indicated in Figs. 3, 4 and 5 of the drawings.

Fig. 4 which is taken through the longitudinal passages 8, 9 and l0 shows clearly the metal at 25 resting within the undercut recesses 22 and 23 thus Arigidly anchoring the tenon at its end. The various transverse or circumferential grooves in the mortise and tenon provide the -rings of metal 26, 27 and 28 which extend entirely about the tenon as indicated in F igs. 3 and 5 and which together with the longitudinal grooves form a grid of metal on each of thewalls of the tenon, securely interlocking it with the entire walls of the mortise. The rings 26, 27 and 28 increase in cross section in the above order and thus interlock to an increasing dcgree with the parts against which they rest, this arrangement giving a maximum interlocking with a minimum weakening of the tenon at the point at which it is exposed to the greatest bendingy stress. Also the inclination of the walls of the various circumferential grooves is most abrupt in the direction in which it is called on to resist pressure. For example, in the metal ring 2S, the walls 29 and 30 are those which are exposed to pressure whenever there is any tendency for the tenon to be pulled out of the mortise. The metal in the crevice 23 provides a rigid bearing between the parts at this point whenever there is any tendency of the member l to rock with respect to the member 13. It is to be undestood that by the term scorching point .is meant such teinperature as will 'substantially affect the surface of wood within the time required for the metal to cool. Y

There is thus provided a joint which is extremely rigid and is substantially unaffected by moisture. Also, no auxiliary devices such as nails or screws are required to complete the joint. n

If it is desired to take the members apart it is necessary only to heat the wood to such a temperature as will melt the metal whereupon the tenon is readily removed from the mortise, and the metal may be saved for the reassembling of the joint. It may also be noted at this point that in certain fusibleV alloys like the above the inetal upon solidiicati'on expands instead of contracts and thus fits more tightly.

As various changes may be made in the above construction and as the above described art may be carried on in other ways it is to be understood rthat all matter herein lli described and all matter shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Having described this invention, I claim- 1. In joint construction, lin combination a member provided with a tenon, a member provided with a mortise, in which said tenon lies, one of said members being wooden, and a member interlocking with said tenon and the walls of said mortise and formed of a metallic alloy fusible at a temperature below the scorching point of the wood.

2. In joint construction, in combination a wooden member provided with a tenon, a wooden member provided with a mortise in which said tenon lies and a member extending between said tenon and the walls of said mortise and interlocking with the surfaces of both of the same, said latter member being formed of a metallic alloy fusible at a temperature below the scorching point of the Wood.

3. In joint construction, in combination a wooden member provided with a tenon, a wooden member provided with a mortise in which said tenon lies and a member extending between the tenon and the walls of said mortise interlocking with the surfaces of both of the same, said latter member being formed of a metallic alloy constituted to tend to expand upon solidication.

4. In joint construction, in combination, a wooden member provided with a tenon, a wooden member provided with a mortise in which said tenon lies and a member extending between the tenon and the walls of said mortise interlocking with the surfaces of both of the same, said last member being formed of a metal fusible at a low temperature and shaped to' enter and interlock with the pores of the wood.

5. In joint construction, in combination a wooden member provided with a tenon, a wooden member provided with a mortise in which said tenon lies and a metal member fusible at a low temperature and extending between said tenon and said mortise, said member being shaped to enter the pores of the wood with which it contacts.

6. In joint construction, in combination, a wooden member having a mortise formed therein, a second wooden member having a tenon resting within said mortise, said parts being so formed as to provide a passage extending from the lower to the upper portion of said mortise with said tenon positioned therein, and a retaining member formed of a metallic alloy fusible through wood interposed between said tenon and the walls of said mortise.

7. In joint construction, in combination, a pair of wooden members in one of which is a recess and the other of which fits in said recess, substantially registering grooves formed in the walls of said recess, and in the outer surface of the member therein and holding means formed of an alloy fusible through wood resting within said registering vgrooves and locking said members in an assembled relation.

8. In joint construction, in combination, a pair of members, one of which is recessed a-nd the other of which fits within said recess, one of said members being provided with a transverse groove opposite which the other member rests, said groove being formed to provide a more abrupt surface in one direction than in the other, and holding means formed of an alloy fusible at a low temerature cast within said groove and tending to hold said members together.

9. In oint construction, in combination, a pair of members one 'of which is recessed and the other of which fits within said recess, grooves extending about the walls of said recess transverse to its depth and each having a more abrupt surface in the direction toward the open end of the said recess than in the reverse direction, said second member being provided with grooves substantially registered with said first grooves with the parts in assembled relation, said last each having a surface toward the bottom of the recess; more abrupt than that toward the top, and holding means formed of a metallic alloy fusible at a low temperature cast within said grooves.

10. In joint construction, in combination, a member provided with a recess, a second member fitted within said recess, said rst member having a series of grooves extending about the walls of said recess and said second member having a series of substantially registering grooves and holding means formed of a metallic alloy fusible at low temperature fitted within said grooves, said several grooves being of increasing depth in a direction toward the bottom of said recess.

l1. In joint construction, in combination a member provided with a recess, a second member fitting said recess, a series of grooves extending about the surface of one of said members at a point opposite the surface of the other of said members within said recess and holding means formed of a metal fusible through wood cast within said grooves, said grooves being shaped to comprise portions extending toward the open end of the recesses whereby said metal may flow toward said end.

12. In joint construction, in combination, a wooden member provided withxa mortise, a wooden member provided with a tenon, a series of substantially registering grooves formed in the outer surface of said tenon and the walls of said mortise and extending about said mortise whereby there is provided a series of circumferential passages about said tenon and entering into said tenon and the walls of said mortise and holding means formed of an alloy fusible through wood cast within said passage.

13. In joint construction, in combination, a pair of wooden members forming a mortise and tenon and holding means formed of an alloy fusible through wood, interposed between said tenon and mortise and provided with outer inclined surfaces upon opposite sides of said tenon interlocking with the walls of said mortise.

14;. In joint construction, in combination, a wooden member provided with a mortise, a wooden member provlded with a tenon Vresting within said mortise, and a shoulder awooden member provided with a tenon .fitting within said mortise, and a member formed of an alloy fusible through wood, entering into the end of said tenon and the bottom wall of said mortise.

16. In joint construction, in combination, a pair of wooden members, one of which has a mortise formed therein, and the other of which has a tenon fitting within said mortise, and a member formed of an alloy fusible through wood and shaped to lock together said mortise and tenon.

17. The art which comprises forming a mortise with undercut walls in a wooden -member, forming Ia tenon upon a second wooden member7 heating said mortise and tenon, placing a molten metallic alloy fusible at low temperature within said mortise,

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