The present invention concerns the joinery field and deals with a steady pin in order to joint more members together to obtain a particular resistance to stress; it concerns also the process of the jointing by using the steady pin.

The invention can be particularly applied to joint members of wood of house furniture such as chairs, tables, chest of drawers.

In the joinery field, it is necessary to joint stiles and cross members together, as well as heartwood members jointed together by the side or by right angle, as well as members jointed by chamfering; usually in order to replace the traditional jointing processes by tenon and mortise or by dovetail- joint, almost cylindrical wood steady pins are being used having side surfaces conveniently fluted, which are inserted by clamping them into special cylindrical cavities present on the two members to be jointed; in order to fasten the joint it is necessary to make use of special glues.

The joints carried out using traditional steady pins present the incovenience to be particularly weak if carried out without using glue, whereas making use of said co po- nents, the leak of the liquid from its seat may often occur, causing aesthetical and manufacturing inconveniences in case of further working processes; in particular the removal of the glue in excess adds additional handwork and affects the total cost of manufacturing process, whereas the painting results to be difficult being the chemical composition of the glues incompatible to restrain the substances of the paints usually available on the market.

A further inconvenience is that the mechanical resistance of the joint is limited and frequently the two parts, stressing or under the shrinkiage of the wood fibers due to

the ageing of the wood, remove from each other or cracks may occur on the joints.

A first aim of the present invention is to carry out a steady pin which is able to carry out joints by high mechanical resistance also without making use of glues or adhesives.

A further aim is to carry out a steady pin and a jointing process which allows irreversible joints also when a structural modification of the fibres of the parts to be jointed may occur. A further aim is to carry out a steady pin and a process for jointing which makes easy the assembling steps being based on the industrialized manufacturing of the parts to be jointed.

Last but not least aim is to obtain a steady pin and its corresponding using process which is easy and inexpensive and obtained without specialized handwork or sophistica¬ ted technologies.

These and further aims are been achieved by a steady pin for jointing wood parts characterized by a cylindri- cai steady pin body provided on each of its terminal portions with a housing fit for receiving inside a whole member which warps said terminal portions and having a first cylindrical portion and a second truncated-cone portion arising from said first portion starting from the minor base, said steady pin fit for being inserted into hollow seats carried out inside the parts to be jointed countershaped according to the profile obtained by the warping of said terminal portions which is caused by inserting said members into the corresponding housings.

Further features and advantages will more clearly arise from the description of preferred embodiment but not exclusive of the steady pin shown only by way of example but not exclusive in the enclosed drawings where:

- figure 1 shows an assonometric view of one of the terminal parts of the steady pin;

- figure 2 shows a detail of an assonometric and exploded view of a joint with the steady pin between cross member and a chair leg;

- figure 3 shows the cross section of a joint with the steady pin before being forced into its corresponding hollow seat carried out on the part;

- figure 4 shows the cross section of a joint with the steady pin after being forced into the corresponding hollow seat carried out on the part;

- figure 5 shows a section of an alternative shape of the wedge; - figure 6 shows the tip of a tool suitable to carry out the hollow seats inside the parts to be jointed;

- figure 7 shows a hollow seat carried out with the tip of the tool;

- figure 8 shows a corner joint carried out by using the steady pin;

- figures from 9 to 13 show different alternative embodiments of the steady pin.

The steady pin of this invention presents a steady pin body 1, which in the preferred embodiment is of a cylindrical shape, having in each terminal portions 2 and 3, respectively a hollow seat 4 and a hollow seat 5 both cylindrical and coaxial according to said steady pin body 1.

The dimension of each section of said hollow seats are about equal to those of a first portion 8 of a wedge 6; referring to figure 1 said wedge presents a first portion 8 whose side surface 12 is provided with a plurality of parallel annular grooves and a second truncated-cone portion 10 which arises from said first portion starting from the minor base 13.

When the invention has to be used, a hollow housing 14 is present having a first cylindrical portion 18 which arises radially into a second and adjacent truncated-cone portion 20, said two portions having the same circumference 22; in the same way on the other member to be jointed, an identical housing arising from the hollow seats 15 will be obtained resulting half from a first cylindrical portion 19 and half from a second trunca¬ ted-cone portion 21 having the same circumference 23.

The terminal portions 2 and 3 of the steady pin body 1 with the wedges 6 and 7 respectively inserted inside the hollow seats 4 and 5 will be housed into the housings 14 and 15 obtained on the parts to be jointed as represented as an example in figure 2 and showing a chair leg 17 and a cross member 16. The hollow seats as represented in figure 2 and pointed out by numbers 14 and 15 or according to the embodiments previously descripted, are obtained by means of a tip of a tool 50 having a body 51 whose terminal part 52 has a truncated-cone shape 53 provided with at least a first main cutting-edge 54 and of a second cutting-edge 55.

The hollow seat 58 showed in figure 7 is carried out during following working steps, the first of which foresees the tip of the tool 50 moving forward into the part 59 according to a vertical rectilineal direction corresponding to axis 60, carrying out the material removal; the second step foresees the motion of translation of said tool tip according to a radial direction towards outside according to direction 61 and a further and third step which completes the working process and foresees the tool pin 50 working according to an annular direction 62.

Each working step foresees a radial motion of translation of the tool tip 50 according to direction 61 of variable lenght such to allow to obtain a hollow seat 58 correspon¬ ding to the dimensions required, whereas the horizontal section of said hollow seat will arise from the direction which said tool tip will take simply varying the direction 62, according to the suitable embodiments for each use of the invention.

In order to use the steady pin of the present invention, a first insertion of the wedges 6 and 7 with the first portions 8 and 9 respectively into the hollows seats 4 and 5 is foreseen, adding if necessary a small quantity of glue in said hoi low seats.

Afterwards the terminal portions 2 and 3 of the steady pin body 1 with the respective wedges 6 and 7 are

inserted respectively into the hollow seats 14 and 15 of the parts 16 and 17 to joint.

A clamping strenght is being applied in order to draw near the two parts 16 and 17 determining the full insertion of the wedges 6 and 7 into the respective hollow seats 4 and 5 and causing the consequent warping of the terminal portions 2 and 3 of the steady pin body 1; said terminal portions fit in the shape of said hollow seats 14 and 15 obtaining the joint.

When some glue is been used, as previously mentioned, it is useful to use an alternative shape of the wedges 6 and 7; as described in figure 5 said wedge 6 is provided to the bases 56 and 57 respectively with a hollow seat 66 and 67 fit for receiving the quantity of glue in excess which otherwise would come out or cause some thickness; moreover along the whole side surface 65 of said wedge a plurality of annular grooves are carried out.

In alternative to the preferred and described embodiment, the steady pin of the present invention will be carried out in various and different shapes as showed in figures from 9 to 13. A first alternative embodiment comprises the replacement of the steady pin body having a circular section with a steady pin body 25 having a rectangular section and rounded minor sides, said body provided with two hollow seats 26 and 27 of a similar shape carried out in the respective terminal portions 28 and 29 and with two wedges 30 and 31 also having a rectangular section with rounded minor sides and shaped in a way similar to the main embodiment previously described.

A second alternative embodiment presents a different shape of the hollow seat carried out in a steady pin body having a circular section 40; said hollow seat can be simply obtained by carrying out a carving 41 where a fox-wedge 42 can be housed; said cross-shaped hollow seat 43 obtained by two orthogonal carvings and housing a cross-shaped wedge 44 also foresees in a different embodiment a steady pin body 32 carried out from a single

block with element 33 which has to be joint and that a terminal portion 34, a hollow seat 35 and the corresponding wedge 36 are according to at least one of embodiment previously described.

Further to the described embodiments, others can be consi erated also by combination of them, according to the type of joint to obtain and according to the working processes which have to be carried out; as showed in figure 13 the steady pin body 25 can alternatively be provided in its terminal portion 28 with a carving 38 which is fit for housing the fox-wedge 37 obtaining in such a way a combination among the alternative versions described in figures 9 and 10.

As previously mentioned, also the types of joints can be various, depending on the parts which have to be jointed; in figure 2 is described a joint obtained by drawing near a head of a horizonthal member to the side of a vertical member, whereas in figure 8 a joint obtained by chamfering locked by a pin is shown, where the terminal parts 45 and 46 of the parts are chamfered according to a determined angle carrying out on faces 47 and 48 at least one of the type of hollow seat previously showed housing the corresponding steady pins 39 and 49 according to the invention.

The invention so conceived is susceptile to various modifications and variations, all within the same inventive concept; furthermore all the details can be substituted with others technically equivalent.