Apparatus for joining fusible elements

An apparatus is provided for joining first and second fusible elements. The apparatus includes apparatus for controllably heating the first element to a temperature sufficient for forming a bond with the second element and apparatus for controllably moving the heating apparatus relative to the first element.

BACKGROUND OF THE INVENTION 
Machine parts are often made by investment casting in which molten metal is 
cast in ceramic molds. The ceramic molds are made by coating wax models of 
the finished parts and melting the wax to leave the mold. These wax models 
are sometimes small and several are grouped on a wax support to save 
space. The wax models are dipped in melted wax and are joined to the 
support by hand. Sometimes a joint has air pockets or other cavities which 
are thereafter eliminated by melting the wax in the joint manually with a 
soldering iron. This is a time consuming operation but it must be done to 
prevent imperfect finished machine parts which cannot be used. Time spent 
in wax welding with a soldering iron and reworking imperfect joints and 
parts is a very large portion of the total time required to produce the 
machine parts. It is desirable to obtain a joint which is acceptable 
without manually soldering with a hand held soldering iron. It is 
desirable to join the wax models to the support in an efficient manner. 
SUMMARY OF THE INVENTION 
The present invention is directed to overcoming one or more of the problems 
as set forth above. 
According to the present invention, apparatus is provided for joining first 
and second fusible elements. The apparatus includes apparatus for 
controllably heating the first element to a temperature sufficient for 
forming a bond with the second element. The apparatus also includes 
apparatus for controllably moving the heating apparatus along the first 
element in a preselected pathway.

DETAILED DESCRIPTION 
Referring to FIG. 1, apparatus 10 is provided for joining first and second 
fusible elements 12, 14, such as first and second wax elements, for 
example. The first element 12 preferably has a groove 16 and the second 
element preferably has a tongue 18 mateable with the groove 16 (FIG. 3). 
Other arrangements such as holes and mateable dowels are used where 
appropriate to mount the second element 14 on the first element 12. The 
groove 16 or holes form a pathway 20 along which the elements 12, 14 are 
joined to form a unitary structure 21. The first element 12 is supported 
by a pair of generally upright support members 22, 24 each having 
removably mounted end portions 26, 28 respectively. The end portions 26, 
28 have a size and configuration sufficient for supporting the first 
element 12. 
The apparatus includes means for controllably heating selected portions of 
the first element 12, such as a heating element 30, and means for 
controllably moving the heating element 30 along the pathway 20. The 
heating element 30 is electromagnetically heated, preferably by current 
flow through the heating element 30, and heats first element 12 to a 
temperature sufficient for melting the first element 12 and subsequently 
forming a bond with the second element 14. The heating element 30 has a 
tip 32 which is preferably removably mounted, and is of a size and 
configuration sufficient for heating selected portions of the first 
element 12. For example, the tip 32 would have a tongue 34 to extend into 
the groove 16 of the first element 12. 
Referring to FIGS. 1-3, the moving means includes a support assembly 36 so 
constructed and arranged that the heating element 30 is supported by the 
support assembly 36 and movable in three mutually generally perpendicular 
planes. The heating element 30 is preferably moved by electric stepping 
motors 38 (FIG. 5), but other motors, such as pneumatic or hydraulic 
motors for example, can be used. The heating element 30 is movable along 
the pathway 20 at a preselected attitude relative to the first element 12. 
It should be understood that the pathway of movement can be other than 
linear and the attitude can be in contact with the first element 12, 
spaced a preselected distance from said first element 12 or a combination 
thereof for melting, for example, spaced preselected portions of said 
first element 12. 
Referring to FIGS. 1-3 and 5, the moving means includes first, second, and 
third support assemblies 40, 42, 44. The first assembly 40 is connected to 
the heating element 30 and moves the heating element 30 generally 
vertically to a preselected attitude relative to the first element 12. The 
first assembly 40 includes a base 46 having generally horizontal and 
vertical openings 48, 50 therein, an elongated generally upright member 52 
and a bracket 54. The elongated member 52 is movably mounted on the base 
40 and the bracket 54 which holds the heating element 30 is mounted on the 
elongated member 52. 
The second support assembly 42 is movably connected to the first support 
assembly 40 and moves the heating element 30 generally laterally in 
substantially a straight path, east-west for example. The second assembly 
42 includes a base plate 56 and braces 57 which support a pair of 
spaced-apart, generally upright supports 58, 60 and one or more, 
preferably two, elongated cross members 62 connected to the upright 
supports 58, 60 in opposed relation to the base plate 56. The cross 
members 62 are disposed in the horizontal openings 48 of the base 46 to 
the first assembly 40. The first assembly 40 moves along the cross members 
62. 
The third support assembly 44 is movably connected to the second support 
assembly 42 and moves the heating element 30 generally laterally in 
substantially a straight path, north-south for example, which is generally 
perpendicular to the path of the first and second assemblies 40, 42. The 
third assembly 44 includes a base plate 64 which supports a pair of 
spacedapart elongated members 66, 68. The second assembly 42 rides on the 
base plate 64 between the elongated members 66, 68. 
Referring to FIGS. 1 and 2, pneumatic motors, such as double acting air 
cylinders 70, 72 and 74, are conveniently mounted on the support assembly 
36 and control the movement of the first, second and third assemblies 40, 
42 and 44. 
Referring to FIG. 4, each of the air cylinders 70, 72 and 74 are 
controllably connected to an air supply 76 by levers 80, 82 and 84, 
respectively. The air cylinder 70 is equipped with a check valve 86 and a 
gauge 88 for each air line 90 for measuring speed or pressure. The other 
cylinders 72, 74 are similarly equipped. The check valve 86 allows air 
flow in a preselected direction when the lever 80 is operated by hand or 
preferably by foot. 
Referring to FIG. 5, the air cylinders 70, 72 and 74 are replaced by the 
preferred electric stepping motor 38. The electric stepping motor 38 is 
preferred since it more precisely controls movement and it is readily 
adaptable for use with automatic control systems. The support assembly 36 
can have notched surfaces wherein the notches are compatible with 
individual steps of the stepping motor 38. 
In operation, the heating element 30 is passed along the preselected 
pathway 20 at a preselected attitude relative to the first element 12. The 
rate of movement is controlled by the stepping motors 38 so that 
preselected portions of the first element 12 are melted. Selected portions 
of the second element 14 can be dipped in melted wax and urged against the 
first element 14 at a preselected location while selected portions of each 
element 12, 14 are in a fluid condition. This forms a unitary structure 21 
which is substantially free of voids between the first and second 
elements. An operator can control the rate of movement with his feet while 
leaving his hands free to urge the elements 12, 14 together. The 
preselected pathway can also be controlled to provide an infinite number 
of melted portions of an infinite number of different configurations and 
locations. 
Other aspects, objects and advantages will become apparent from a study of 
the specification, drawings and appended claims.