US2947849A - Apparatus and method for constructing pivotal connections - Google Patents

Description

1960 o. T. woon 2,947,849

. APPARATUS AND METHOD FOR CONSTRUCTING PIVOTAL CONNECTIONS Filed March 5, 1957 2 Sheets-Sheet l INVENTOR.

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0. T. WOOD APPARATUS AND METHOD FOR CONSTRUCTING PIVOTAL CONNECTIONS Filed March 5, 1957 2 Sheets-Sheet 2 INVENTOR. Orville ZZZ/00d, BY

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United States Patent Ollice 2,947,849 Patented Aug. 2, 1960 APPARATUS AND METHOD FOR CONSTRUCTING PIVOTAL CONNECTIONS Orville T. Wood, Essex, Cnn., assignor to Pratt, Read and Co., Incorporated, Ivoryton, 'Conn., a corporation of Connecticut Filed Mar. 5, 1957, Ser. No. 644,153

9 Claims. (Cl. 219150) be made so that there are little or no frictional or knocking noises arising from contact between the moving parts of the action. It has been standard practice in the past to use wooden parts in piano actions and to provide bearings in such actions wherein holes are drilled in the wooden parts and lined with felt or other material to provide a smooth, noiseless movement. The parts are connected by wires or pins which are positioned in the lined holes in the wooden members to provide quietly operated pivotal connections. Although such connections have been generally used, and have provided quiet, eflicient operation when new, the felt lining material tends to absorb moisture and is subject to wear. Accordingly, the operating characteristics of such actions change with changes in humidity, and also change as a result of wearing of the felt or other lining material with extended periods of use. In the past it has been proposed to use other types of pivotal connections for piano actions but no satisfactory solution was found which could be constructed inexpensively so that the action using such connection could be manufactured at reasonable cost.

In the copending application of Paul F. Murdock and Charles M. Pratt, Serial No. 581,747, filed April 30, 1956, now Patent No. 2,877,537, and entitled Method of Constructing a Piano Action, there is described a piano action having an improved pivotal connection. In the piano action described in that application, a wood hammer butt is pivotally mounted on a plastic flange using a metal pin. The metal pin is slightly larger than the holes in the plastic flange and in the hammer butt and forms a wedge fit in both members. The metal pin is heated electrically after insertion through the flange and hammer butt and causes the plastic in the flange around the pin to fuse and provide a smooth bearing surface for the rotation of the pin with the piano hammer In order to prepare this piano action economically, it is desirable that there be provided a suitable method and apparatus for assembling the piano actions rapidly and efliciently.

It is therefore one object of this invention to provide an improved method and apparatus for assembling piano actions having a simple and improved pivotal connection.

Another object of this invention is to provide an improved method and apparatus for preparing an effective pivotal connection between a plastic member and a member made of wood.

Another object of this invention is to provide an improved apparatus for making a pivotal connection between a plastic flange and a wooden hammer butt in a piano action.

A further object of this invention is to provide an improved apparatus for making pivotal connections between plastic flanges and wooden hammer butts in piano actions rapidly and economically.

' A feature of this invention is the provision of an apparatus for inserting a pin through a plastic flange and wooden hammer butt of a piano action and electrically heating the pin to form a smooth bearing for a rotary movement of the pin and hammer.

Another feature of this invention is the provision of a method for making a pivotal connection for a wooden hammer butt and plastic flange of a piano action having a means to feed connection pins in rapid succession and a means to insert the pins into successive flanges and hammer butts.

A further feature of this invention is the provision of an apparatus for making a pivotal connection between a wooden hammer butt and a plastic flange in a piano action in which a metal pin is inserted through the flange and hammer butt and heated by an electrical induction coil to fuse or soften the plastic around the pin to provide a smooth bearing.

A further feature of this invention isthe provision of a method for making a pivotal connection between a wood member and a plastic member wherein the wood member has a hole with a liner of a plastic material therein and the size of the liner hole and the hole in the plastic member is smaller than the pivot pin, and a pivot pin is inserted through said holes to compress the mau terial about the openings and is then heated to a temperature which softens or fuses the plastic member to provide a smooth bearing and which fuses the plastic lining to form a tight connection between the wooden member and the pin.

Further objects, features and advantages of this in vention will be apparent from time to time throughout the specifications and claims as hereafter related. In the accompanying drawings, to be taken as part of this specification, there are clearly and fully illustrated a preferred embodiment and several modifications of this invention, in which drawings;

Fig. 1 shows a pivotal mounting for a hammer of a piano action;

Fig. 2 is a cross-section taken on the line 2-2 of Fig. l and shows the pivotal connection between the wooden hammer butt and the plastic supporting flange;

Fig. 3 is a diagrammatic view of an apparatus for feeding and positioning pivot pins in the flange-hammer butt joint of a piano action and having an electrical induction heating coil therefor;

Fig. 4 is a diagrammatic view illustrating a process of assembling a pivotal connection for a wooden hammer butt and a plastic flange of a piano action using a rod which is scored to be broken into lengths corresponding to a pivot pin and having an electric induction coil for heating the pin prior to insertion into the joint of the piano action;

Fig. 5 is a detail view of part of the apparatus shown in Fig. 3 in which the Wooden hammer butt has a plastic lining in the pivot hole therein which is adapted to be fused to the wood and to the pivot pin;

Fig. 6 is an enlarged sectional view of the pivotal connection for the piano action shown in Fig. 5 subsequent to the application of heat to the pivot pin;

Fig. 7 is a diagrammatic view of an apparatus similar to that disclosed in Fig. 3 for assembling pivot pins in a piano action and having electrical resistance heaters for heating the pivot pin prior to and during its insertion into the piano action; and

Fig. 8 is a diagrammatic view of an apparatus similar to that shown in Fig. 7 arranged to automatically complete a circuit through the pivot pin upon its insertion through the parts which are joined thereby to cause the pin to berheated and thus form a smooth plastic bearing for the action.

In this invention there is provided an apparatus for forming a pivotal connection between a plastic member, such as a plastic flange, and a wood member, such as the wooden butt of a piano hammer, by insertion of a pivot pin therein. The wood and plastic members are provided with openings which are smaller than the diameter of the pin and with the opening of the wood member being preferably smaller than the opening in the plastic member. The pin is preferably made of metal and upon insertion through the openings in the wood and plastic members compresses the material about the openings. The apparatus includes a hopper and flexible feeding tube for supplying pins to a guide member aligned with the wood and plastic members which are to be connected together. A mechanically actuated ram forces the pin through the openings in the wood and plastic members.

After the pin is driven through the openings in the wood and plastic members it is heated electrically to soften the compressed plastic material so that it fuses and flows suificiently to relieve the pressure on the pin and to provide a smooth bearing surface about the pin. The pin, during the electrical heating, is held at a temperature which is suificiently high to cause the plastic to soften but which is sutficiently low that the wood is not charred by the heat from the pin. The temperatures in the range from 150 to 225 F. may be suitable for this purpose. The term fuse or fusing of plastic as used herein includes the mere softening of the plastic with heating so that it flows. The electrical heating means for heating the pivot pin may involve the use of the pin as an electrical resistor by passing electrical current directly therethrough. The pin may also be heated by induction heating produced by an electrical induction coil held in close proximity thereto. In one modification of the invention the pivot pin is electrically heated before it is inserted through the openings in the plastic and wood members. In another modification of the invention the aperture or opening in the wood member is provided with a plastic lining which upon being heated by the pin is fused and provides a tight connection between the pin and the wood member. In this modification of the invention the pin may having a knurled surface to produce a tighter connection with the plastic linmg.

Referring to the drawings by numerals of reference and more particularly to Fig. 1 there is shown a piano action which includes a hammer having a striking head 11 and a supporting butt 12 which is pivotally mounted to a flange 13. The supporting flange I3 is preferably formed of a thermoplastic material having a relatively low softening point and may be secured to a fixed rail structure of the piano action. A catcher '14 is secured to the hammer butt l2 and a buckskin with felt undercloth is provided thereon for engagement by a fly-jack operated by the keys of the piano. The construction of the hammer itself is Well known and there is not need for further description.

As previously indicated it is essential to have a smooth operating pivotal bearing connection between the flange 13 and the hammer butt 12. The connection must be free of vibrational and frictional noise and must provide a straight line movement with no lateral play in the movement of the hammer butt 12. The hammer butt 12 is made of wood as in the conventional construction generally in use. The flange member 13 is of a molded plastic material, preferably a thermoplastic, which may be easily molded in large quantities at very small unit expense.

In Fig. 2 there is shown in cross-section the pivotal connection between the hammer butt 12 formed of wood and the flange 13 of plastic. The pivotal connection is 4 i 7 provided by a metal pin 16 which passes through openings in the two spaced support arms '17 of the flange 13 and in the pivot bearing portion 18 of the hammer butt 12. The openings in the plastic flange 13 and in the wood hammer butt bearing portion 18 are preferably of smaller diameter than the diameter of the metal pin 16 which is inserted therein. Thus when the pin is positioned in the openings the material adjacent thereto is compressed and very tight fit is provided both in the plastic flange and in the wood hammer butt. When the pin 16 is heated to a temperature above the softening point of the plastic material of the flange 13 (about to 225 F.) the plastic material around the pin softens or fuses and provides a very smooth bearing contact with the pin which permits the pin to turn within the flange and provides a pivot bearing. As long as the temperature is held below about 225 F. the moisture in the Wood absorbs the heat and no charring eifect on the wood hammer butt is produced. Accordingly, the tight connection between the pin and the wood hammer butt is retained so that the pin moves with the hammer butt while the plastic softens and forms a smooth bearing in which the pin may turn.

In a number of operating tests cellulose acetatebutyrate,

ethyl cellulose, and polyethylene have been found to besatisfactory materials for the manufacture of plastic flanges for piano actions made in the above described manner. The openings in the plastic flanges are formed by drilling to a selected diameter, e.g., .046 inch. These holes are then reamed to a selected final diameter, e.g. .049 to .050 inch. The holes in the wooden bearing portion of the hammer butt 12 are preferably slightly smaller than those in the plastic flange member, e.g., .0475 to .0495 inch. When using plastic flanges and wood butts having holes of the above specified sizes the metal pins which are used have a slightly larger diameter, preferably about .05075 to .05100 inch. The metal pin 16 is preferably formed of a metal wire or rod having a high electrical resistance e.g. 8% 'ckel silver, so that it may be heated easily by passing an electric current there through.

In Fig. 3 there is shown diagrammatically an apparatus for assembling a plastic-wood pivotal joint in the manner above described. In this apparatus there is provided a hopper 29 for containing a plurality of pivot pins and having a flexible supply tube 22. At the lower end of the flexible supply tube 22 there is provided a guide block 24 having a guide passage 25 therein and arranged for lateral movement by a suitable moving means such as a hydraulic cylinder and piston arrangement 23. Positioned below the movable guide block 26 there is located a fixed guide block 3%) having a guide passage 32 therethrough. Below the fixed guide block 30 there is positioned a fixed supporting base 34 and an electric induction heater coil 36 for heating the pivot pins which are inserted in the hinge assembly. Above the fixed guide block 30 there is positioned a ram 38 having an end portion 40 aligned with and reciprocally movable into and out of the guide passage 32. The ram 38 may be actuated by any suitable actuating means such as a hydraulic cylinder arrangement 42.

In the operation of this apparatus a wooden hammer butt 12 is positioned with its pivotal supporting portion 18 located between the supporting arms 17 of a plastic flange 13. The assembled flange and hammer butt are positioned with their pivot apertures aligned with the 1 guide aperture 32 in the guide-block 30. The actuating member 28 is then operated to move the guide block 24 and flexible supply tube 22 into position with the aperture 26 aligned with the guide passage 32. In this position one of the guide pins 16 is dropped into the guide passage 32. The actuating cylindef 28 then moves the guide block 24 and flexible supply tube 22 away from the fixed guide block 36) to the position indicated by the dotted lines in Fig. 3. The actuating cylinder/42 is then actuated to move the ram 38 to drive its end portion 40 into the guide passage 32 to drive the pin 16 through the aligned apertures in the flange 13 and hammer butt 12. When the pin 16 is driven into position to connect the plastic flange 13 to the wooden hammer butt 12 the electrical induction coil 36 is energized to heat the pin 16 by a high frequency induction current. When the pin 16 is thus heated the plastic around the pin will fuse in the manner previously described to provide a smooth bearing for rotation of the pin 16 and the hammer butt 12.

The sequence of operation thus described may obviously be performed by suitable automatic equipment. Thus the hammer butt 12 and flange 13 may be assembled and fed into position by a suitable conveyer means. A suitable timing sequence mechanism can be used to actuate the cylinder 28 to feed metal pins to the guide passage 32 in the guide block 30. Similarly automatic equipment may be used to actuate the ram 38 and to turn on the induction heating coil 36. While it is preferred to turn on the induction coil 36 to heat the pin 16 after insertion through the flange 13 and hammer butt 12 this heater coil could be energized to heat the pin prior to insertion if desired.

In Fig. 4 there is shown a slightly modified form of this invention. In this modification the actuating and guide means are not shown. In this method and apparatus for assembling plastic to wood pivotal joints the pivot pins are supplied in the form of a long thin rod or wire 116 which is scored at selected points along its length so that it may be broken into separate pivot pins 16. The rod 116 is passed through an induction heating coil 36 and heated to a selected temperature above the softening point of the plastic flange 16. The heated rod is inserted through the aligned apertures in the plastic flange 13 and the hammer butt 12. As the heated rod passes through the apertures in the plastic flange 13, the material of the plastic flange will soften and form a smooth joint for the pivot pin While the pin will make a tight compressive joint in the wooden hammer butt 12. When the pin is inserted in the joint the pivotal assembly may be twisted to a position indicated by the dotted lines in Fig. 4 to break off the pivot pins 16 at one of the scored points on the rod 116. The method of assembly may be carried out using the same automatic feeding and ramming apparatus disclosed in Fig. 3. The twisting of the pivotal assembly to break off the pivot pin 16 could be done either manually or by a pivoted supporting base arrangement.

In Figs. 5 and 6 there is shown a modified method for assembly of a pivotal joint for a piano action using the same apparatus disclosed and described in connection with Fig. 3. In Figs. 5 and 6 only a portion of the apparatus is shown and the various parts have the same reference numerals as in Fig. 3. In this method of assembly the pivot pins 16 are provided With a knurled center section 46 which is of the same width as the pivotal supporting portion 18 of the wooden hammer butt 12. The aperture or passage through the supporting portion 18 of the hammer butt 12 is slightly enlarged and is provided with a thermoplastic insert or liner 44. The method of operation of the apparatus is the same as in Fig. 3. However, the pin 16 is positioned with a tight fit in the supporting legs 17 of the plastic flange '13 and in the plastic liner 44 in the supporting portion 18 of the wood hammer butt 12. When the pin 16 is heated, by the induction heating coil 36 or by any other heating means, the plastic liner 44 is fused to form a tight bond with the wood supporting portion 18 of the hammer butt 12 and flows into and around the knurled portion 40 of the pin 16 to provide a tight connection thereto. In Fig. 6 the joint is shown in section in the condition produced after the heating of the pivot pin 16. In this condition the hammer butt 12 is tightly and non-rotatably secured to the knurled portion 46 of the pin 16 and the pin 16 is provided with a smooth plastic bearing for rotation in the supporting portion 17 of the plastic flange 13.

In Fig. 7 there is shown a further modification of the apparatus described in connection with Fig. 3 in which the induction heating coil is replaced with a system of electrical resistance heaters. In this apparatus there is provided a hopper '20 and a flexible supply tube 22 leading to a movable guide block 24 having a passage 26 therein. There is also provided a fixed guide block having a guide passage 32 which is adapted to be aligned with the guide passage 26 in the movable guide block 24 to receive a pivot pin 16 fed therethrough. As in the other forms of the invention the plastic flange 13 and wood butt 12 are supported on a fixed surface 34 with the pivot apertures aligned with the passages 32 in the guide block 30. The movable guide block 24 and flexible supply tube 22 are moved back and forth by an actuating means such as a control cylinder 28. The pivot pins 16 which are dropped into the guide passage 32 by the hopper and feed arrangement are driven into the aligned apertures in the plastic flange 13 and wooden hammer butt 12 by a ram member 38 having an end portion 40 aligned with and movable into the guide passage 32 by a suitable actuating means such as a control cylinder 42. The hopper 20 in which the pivot pins 16 are stored is provided with an electrical resistance heater 50 which is energized from a power source 52. The movable guide block 24 is heated by an electrical resistor 54 which is connected by extensible conductors 56 to the power source 52. The fixed guide block 30 is heated with a resistance heater 58 which is connected to the power source 52. The ram member 38 is also connected by extensible conductors 60 and 62 to the power source 52 and is heated by the passage of electric current therethrough. In this form of the invention the pivot pins 16 are heated in the hopper and maintained in a heated condition by the electric resistance heater for the movable guide block 24 and fixed guide block 30 and by the heated ram 38 so that the pins are at a sufli ciently high temperature to cause the plastic of the flange 13 to soften as they are driven through the apertures. This provides a smooth bearing surface for the pivot pins 16 as in the other embodiments of the invention.

In Fig. 8 there is shown a further embodiment of this apparatus in which there is provided a means for heating the pivot pins v16 by passing an electric current therethrough simultaneously with the insertion of the pin in the apertures in the plastic flangeand wooden hammer butt. In this apparatus there is provided a storage hopper 20 for the pivot pins 16 having a flexible supply conduit 22 which is connected to a movable guide block 24 having a guide passage 26 therein. The movable guide block 24 is arranged for actuation by a suitable actuating means 28 which may be a hydraulic cylinder or the like. The movable guide block 24 is arranged to be aligned with a fixed guide block having a guide aperture 32 therein. The plastic flange 13 and wooden hammer butt 12 are arranged to be supported on a supporting block member 66 having an aperture therethrough with a movable metal pin 68 therein which is urged upwardly by a spring member 70. The pins 16 which are fed from the hopper 20 through the flexible supply tube 22 and movable guide block 24 are rammed into the aligned apertures of the plastic flange :13 and wooden hammer butt 12 by a ram member 38 having a ramming portion 40 of reduced diameter and arranged for actuation by a suitable actuating means such as a hydraulic cylinder 42. The ram portion 40 is connected as at 76 to an extensible lead 74 from a power source 72. The pin 68 in the supporting block 66 is connected as at 80 to a power source 72 by an extensible electric conductor 78.

In the operation of this apparatus the hopper 20, flexible tube 22, guide block 24, and actuator 28 function as in the previous embodiments of the invention to supply pivot pins 16 to the fixed guide block 30. The actuating means or cylinder 4-2 movesthe end portion 40 of the ram 38 into the guide passage 32 in the fixed guide block 30 to ram the pivot pin 16 throughthe aligned apertures in the flange 13 and wooden hammer butt 12. When the end portion 40 of the ram 38 drives the pivot pin 16 into engagement with the pin 68 an electric circuit is completed through the pivot pin 16. This causes the pivot pin 16 to be heated to fuse the plastic in the apertures in the flange 13 to provide the smooth plastic bearing desired for this pivotal connection. The spring 70 in back of the pin 68 permits a slight overtravel of the ram 38 without damage to the pivot pin. In this embodiment of the invention the pivot pin 16 is automatically heated as soon as it is driven through the members for which it is to provide a pivotal connection and the electrical resistance circuit is automatically deenergized upon retraction of the ram 38.

I claim:

1. Apparatus for assembling the parts forming a pivotal joint which includes a first plastic member, a second member, and a metal pin positioned in apertures in the members, including in combination, guide means having an aperture therein for receiving a metal pin, means to support the first and second members with the apertures aligned with said aperture of said guide means, means to feed metal pivot pins to said guide means, ram means to drive a metal pivot pin in said guide means into the aligned apertures of the first and second members positioned in said support means, and electrical means to heat the metal pivot pin to cause the plastic of the first member to fuse thereabout and form a smooth plastic bearing therewith.

Z. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members, including in combination, guide means for a metal pivot pin, means to support a wooden member and a plastic member with apertures aligned with said guide means, means to feed a metal rod having sections forming pivot pins to said guide means, ram means to drive the metal rod in said guide means, whereby the pivot pin formed by the end section of the rod is inserted into the aligned apertures of a wooden member and a plastic member positioned thereunder, and an electrical induction heating coil arranged to heat the metal pivot pin to cause the plastic to fuse thereabout and form a smooth bearing therefor, said support means being pivotally mounted to bend the metal rod and thereby sever therefrom the pivot pin section inserted in the members.

3. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members including in combination, guide means for receiving a metal pivot pin, means to support a wooden member and a plastic member with apertures aligned with said guide means, means for individually feeding metal pivot pins to said guide means, ram means to drive a metal pivot pin in said guide means into the aligned apertures of a wooden member and a plastic member positioned thereunder, and electrical resistance heater means associated with said guide means to heat the metal pivot pin prior to insertion into said plastic member and said wooden member to cause the plastic in contact therewith to fuse thereabout and form a smooth plastic bearing therefor.

4. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members, including in combination, guide means for a metal pivot pin, means to support a wooden member and a plastic member with apertures aligned with said guide means, means to feed metal pivot pins to said guide means, ram means to drive a metal pivot pin in said guide means into the aligned apertures of a wooden plastic in contact with said pin to fuse thereabout and form a smooth plastic bearing therefor.

5. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members, including in combination, a fixed guide member, means to support a wooden member and a plastic member with apertures aligned with said guide member, a hopper for metal pivot pins, flexible supply conduit means connected to said hopper, means to move said conduit means to supply successive pivot pins to said guide member, ram means movable into said guide member to drive a pivot pin through the aligned apertures of a wooden member and plastic member positioned thereunder, and an electrical induction heating coil positioned to heat the metal pivot pin after insertion into said wooden and plastic members to cause the plastic in contact with the pin to fuse and form a smooth plastic bearing therefor.

6. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures and said members, including in combination, a fixed guide member having a guide aperture therein, a supporting base positioned to support a wooden member and a plastic member with apertures aligned with said guide aperture, a hopper for metal pivot pins, a movable guide member having a guide aperture therein, a flexible supply conduit connected to said hopper and to said movable guide member, means to move said conduit and said movable guide member to and from a position with said guide apertures in alignment to supply a pivot pin to said fixed guide member, ram means movable into the aperture in said fixed guide member upon movement of said movable guide member away from said fixed guide member to drive a pivot pin through the aligned apertures of a wooden member and a plastic member positioned thereunder, and an electrical induction heating coil positioned to heat the metal pivot pin after insertion into said wooden and plastic members to cause the plastic in contact with the pin to fuse and form a smooth plastic bearing therefor.

7. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members, including in combination, a fixed guide member having a guide aperture therein, a supporting base positioned to support a wooden member and a plastic member with apertures aligned with said guide aperture, a hopper for metal pivot pins, a movable guide member having a guide aperture therein, a flexible supply conduit connected to said hopper and to said movable guide member, means to move said conduit and said movable guide member to and from a position with said guide apertures in alignment to supply a pivot pin to said fixed guide member, ram means movable into the aperture in said fixed guide member upon movement of said movable guide member away from said fixed guide member to drive a pivot pin through the aligned apertures of a wooden member and a plastic member positioned thereunder, and a plurality of electrical resistors positioned to heat said hopper, said ram means, and said guide members to maintain said pivot pins at a sufiicient temperature prior to insertion into said wooden and plastic members to cause the plastic in contact with the pin to fuse and form a smooth plastic bearing therefor.

8. An apparatus for making a pivotal connection between a plastic member and a wooden member by driving a metal pin through aligned apertures in said members including in combination, a fixed guide member having a guide aperture therein, a supporting base positioned to support the wooden member and a plastic member with apertures aligned with said guide aperture, a hopper for metal pivot pins, a movable guide member having a guide aperture therein, a flexible supply conduit connected to said hopper and to said movable guide member, means to move said conduit and said movable guide member to and from a position with said guide apertures in alignment to supply a pivot pin to said fixed guide member, ram means movable into the aperture in said fixed guide member upon movement of said movable guide member away from said fixed guide memher to drive a pivot pin through the aligned apertures of a wooden member and a plastic member positioned thereunder, and means including electrical connection to said ram means and to said supporting base to pass an electric current through the pivot pin after said pin is driven through said wooden and plastic members into contact with said supporting base and thereby heating said pin to cause the plastic in contact with the pin to fuse and form a smooth plastic bearing therefor.

9. Apparatus for making a pivotal connection between a first plastic member and a second member by inserting a metal pin formed by a section of a scored metal rod through aligned apertures in the members, said apparatus including in combination, guide means for the metal rod, means to support the first plastic member and the second member with the apertures therein aligned with the rod in said guide means, ram means for moving the metal rod through said guide means, whereby the pin formed by the end section of the rod is inserted into the aligned apertures of the first plastic member and the second member positioned thereunder, and electrical means adapted to be coupled to the metal rod to heat the same so that the plastic of the first member fuses thereabout and forms a smooth bearing therefor, said support means being mounted for movement to bend the metal rod and thereby sever therefrom the pivot pin section inserted in the members.

References Cited in the file of this patent UNITED STATES PATENTS

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