Automatic apparatus for induction hardening

Automatic apparatus for the induction hardening of parts of track links includes a frame for supporting the inductors which can oscillate in a horizontal plane above the links so as to enable the induction hardening of links of different shapes and dimensions, by alteration of the oscillating travel of the frame. A completely automatic system is also provided for locking the links in correspondence with the inductors, which is programmable in dependence on the shape and dimensions of the track links supplied to the hardening apparatus. '

The present invention relates to automatic apparatus for the induction 
hardening of parts of metal objects, particularly parts of track links, of 
the type comprising a fixed structure, inductor means, stepwise conveyor 
means for the objects, and rapid cooling means for the objects downstream 
of the inductor means. 
Known apparatus of the type indicated above enables the hardening of 
objects which are the same as each other, variation in the shape and 
dimensions of the objects necessitating stoppage of the apparatus, 
replacement of the inductor means, and manual adjustment of the relative 
distance between the inductor means and the objects in order to ensure 
effective hardending of the objects themselves. These manual adjustments 
with the apparatus stopped require lengthy downtimes and result in a 
consequent drop in productivity. 
The object of the present invention is to provide an automatic device for 
the induction hardening of parts of metal objects which does not have 
these disadvantages but is simple and cheap to operate. 
According to the invention, this object is achieved by virtue of the fact 
that the inductor means are supported by a frame which is movable in two 
directions in a horizontal plane above the parts of the objects to be 
hardened, and that the apparatus further includes means for reciprocating 
the frame in the two directions so as to impart to the inductor means a 
substantially circular movement in a horizontal plane above the parts of 
the objects to be hardened, and means for moving the frame vertically so 
as to enable adjustment of the vertical distance between the objects and 
the inductor means. 
By virtue of this characteristic, it is possible to harden objects of 
various dimensions inductively without changing the inductors and without 
the need for adjusting the apparatus in order to ensure effective 
induction heating of the objects. Indeed, with a single type of inductor 
having a substantially circular movement in a horizontal plane ensured by 
the apparatus, it is possible effectively to heat objects having a 
substantially identical shape but different dimensions, such as, for 
example, track links for earth moving equipment, etc., for which there is 
a wide range of dimensions although they are of substantially idential 
shapes. 
According to another characteristic, the apparatus further includes means 
for automatically centering and clamping the objects in correspondence 
with the inductors, the means being programmable in dependence on the 
shape and dimensions of the objects to be hardened. 
These means allow the automatic centering of the objects in correspondence 
with the inductors and effective locking thereof so as to avoid relative 
movements between the objects and the inductors during the induction 
heating, such movements possibly causing inadequate depth of hardening. 
According to another characteristic, the drive means for the frame include 
means for adjusting the travel of the frame in each of the said 
directions, the means being programmable in dependence on the shape and 
dimensions of the objects to be hardened. 
Thus, it is possible to arrange the apparatus for hardening objects of 
different dimensions simply and rapidly by operation of a simple control 
terminal.

With reference to the drawings, automatic apparatus for the induction 
hardening of track links for tracked vehicles is indicated 10. As known, 
the track links must be hardened on their backs, in correspondence with 
the parts which will slide on the track-tensioning wheel, the driving 
wheel and on the supporting rollers. 
The apparatus 10 includes a supply zone 12, an induction heating zone 14, 
and a rapid cooling zone 16. 
The supply zone 12, illustrated in detail in FIGS. 4 and 5, comprises two 
slides 17 constituted by idle rollers 18 on which right- and left- hand 
track links, indicated D and S respectively, are fed by gravity. The links 
D and S are conveyed from the slides 17 to a pair of braked-roller 
conveyors 20 which are side by side and guided laterally by fixed guides 
22 and movable guides 24. The distance between the guides 22 and 24, 
indicated d in FIG. 5, may be adjusted by means of a screw-and-nut system 
26 operated through a chain 28 by a geared motor 30. The adjustment of the 
distance d is achieved automatically according to the thickness of the 
links supplied to the device 10. 
The braked-roller belt 20 arranges the links D and S in columns, so that 
they bear against each other and against stop means 31 arranged to ensure 
the supply of one pair of links D and S at a time to the hardening zone 
14. The transfer of the links D and S from the supply zone 12 to the 
induction hardening zone 14 is achieved by means of a pick-up 32 of known 
type arranged to transfer one pair of links at a time from the supply zone 
12 to a plate conveyor 33 located in the hardening zone 14 and cooling 
zone 16. The plate conveyor 33 advances stepwise in phase with the 
movement of the pick-up 32 and is supported by a fixed structure 34 of the 
apparatus 10. 
The structure 34 has four vertical columns 35 in correspondence with which 
a frame 36 is slidable. The slidable frame 36 (FIG. 5) is rectangular in 
plan and is provided with guides 37 for its sliding on the columns 35. The 
columns 35 are fixed at their upper ends to a fixed frame 38 on which is 
mounted a geared motor 39 for driving the vertical translational movement 
of the slidable frame 36 on the columns 35. The transmission of motion 
from the geared motor 39 to the frame 36 is of a type known in itself and 
will not therefore be described. 
The frame 36 has circular cylindrical guide bars 40 located transverse the 
direction of advance of the plate conveyor 33 and fixed at 41 to the frame 
itself. Above the frame 36 is a first auxiliary frame 42 slidingly 
supported by the bars 40 of the frame 36 through guide and bearing wheels 
43. The wheels 43 are rotatably fixed to appendages 49 of the auxiliary 
frame 42. Thus, it is clear that, by virtue of the wheels 43 and the 
guides 40, the auxiliary frame 42 can slide transverse the direction of 
advance of the plate conveyor 33. 
The auxiliary frame 42 also has guide bars 44 located in the plane of the 
frame itself and disposed longitudinally relative to the direction of 
advance of the plate conveyor 33. 
Below the first auxiliary frame 42 and in substantially the same plane as 
the slidable frame 36 is a second auxiliary frame 45 slidably supported by 
the guide bars 44 through bearing and guide wheels 46. The wheels 46 are 
rotatably fixed to appendages 48 of the auxiliary frame 45. It is thus 
clear that the second auxiliary frame 45 can slide longitudinally relative 
to the first auxiliary frame 42 and transversely of the slidable frame 36 
together with the auxiliary frame 42. 
To the side of the slidable frame 36 and supported by the frame itself is a 
geared motor-oscillator unit 50 which is connected to a system comprising 
a crank 51 and connecting rods 52 articulated at 53 to the first auxiliary 
frame 42. Similarly, a geared motor-oscillator unit 56 is fixed to the 
second auxiliary frame 45 and is connected to a system comprising a crank 
56 and connecting rods 57 articulated at 58 to the auxiliary frame 42. The 
crank systems 51 and 56 have respective geared motors 60 and 61 for 
adjusting automatically the length of the crank arm and hence the travel 
of the transverse oscillation of the auxiliary frame 42 and the 
longitudinal oscillation of the auxiliary frame 45. 
The frame 45 is thus given a substantially circular movement resulting from 
the combination of the movements of the frame 42 relative to the frame 36 
and of the frame 45 itself relative to the frame 42. 
Supply sources 65 are fixed in respective spaces 63 in the frame 45 and, 
through connecting conductors 66, support inductor elements 67 located 
above the plate conveyor 33. All the supply sources 65 and their inductor 
elements 67 can thus be made to oscillate in the directions indicated by 
the arrows in FIG. 6, by means of the geared motor-oscillator unit 50 and 
55. The distance between the inductor elements 67 and the plates 33a of 
the plate conveyor 33 can be varied by means of the vertical movement of 
the frame 36 driven by the geared motor 39. 
Downstream of the inductor elements 67, in correspondence with the cooling 
zone 16, cooling showers 68 are provided which are supported by the 
slidable frame 36. Downstream of the plate conveyor 33 is an inclined 
plane 70 on which the hardened links slide under gravity and leave the 
apparatus 10. Laterally and on both sides of the plate conveyor 33 are 
means 72 for centering and clamping the links on the plates 33a in 
correspondence with the inductor elements 67. The means 72 comprise right- 
and left-hand centering tools (for an observer located laterally of the 
conveyor 33) 73 and 74 respectively, which can effect a transverse 
approach movement programmable according to the dimensions of the links D 
and S, and a longitudinal movement for taking up the links themselves. The 
centering tools 73 and 74 are V-shaped for engaging the ends of the links 
and are connected to respective shafts 75 and 76 driven for transverse 
movement, for example by pressurised-fluid actuators (not illustrated) 
having a fixed stroke. In order to adjust the transverse centered position 
of the links, rods 77 and 78 mounted within the shafts 75 and 76 are 
joined to the centering tools 73 and 74 and are driven, for example by a 
screw actuator, so as to be able to vary the distances indicated d' and 
d", in order to alter the position of centering, indicated in broken 
outline in FIG. 7, according to the different types of links on the plates 
33a. 
To advantage, the longitudinal centering movement may be achieved by means 
of a pneumatic actuator 80 which makes all the centering tools 73 and 74 
move simultaneously towards the front and rear ends of each link. 
In order to clamp the links, retaining members 82 are provided which are 
also located laterally of the plates 33a, and each of which includes (see 
FIGS. 8 and 9) a pressurised- fluid actuator 83 supported by a plate 84 
slidable on guides 85 located parallel to the direction of advance of the 
plate conveyor 33. Each actuator 83 has a shaft 86 articulated at 87 to a 
clamping tool 88 having guides with cam profiles 90 slidable relative to 
pins 91 fixed to the plate 84. The cams 90 and the pins 91 allow ends 92 
of the clamping tool 88 to travel, under the action of the fluid actuator 
83, a path of transverse translational movement and vertical displacement, 
so as to come into contact with and force the link (indicated in broken 
outline in FIG. 9) against the respective plate 33a. The plates 84 may 
slide simultaneously on the guides 85 under the action of a geared motor 
95, through, for example, a screw-and- nut mechanism (not illustrated). 
The longitudinal translational movement of the retaining members 82 is an 
automatic adjustment movement and serves to make the clamping effective 
for different types of links having different shapes, without the need to 
replace the clamping ends 92. 
The operation of the apparatus will now be described briefly. An operator 
skilled in the control of the automatic apparatus 10 sets in the data 
relating to a type of link or possibly identifies the type of link to be 
hardened by a characteristic symbol, by means of a terminal (not 
illustrated). The other adjustments effected automatically by the 
apparatus relate to the oscillating travel of the frames 42 and 45 by 
means of the geared motors 60 and 61, the distance between the inductor 
elements 67 and the plates 33a of the conveyor by means of the movement of 
the frame 36 by the geared motor 39, the adjustment of the distances d' 
and d" relating to the centered position of the centering tools 73 and 74 
and the longitudinal position of the retaining members 82 by means of an 
overall movement of the members themselves by means of the geared motor 
95. In continuing the description of the operation of the apparatus 10, 
reference will be made solely to the right-hand side and to the right-hand 
links D, the operation of the other side for hardening of the left-hand 
links S being exactly the same. 
The links D deposited on the plates 33a by the pick-up 32 as a result of 
the successive stepwise advances of the conveyor 33 come into 
correspondence with the inductor elements 67. With the conveyor 33 stopped 
and the auxiliary frames 42 and 44 stationary, the shafts 75 and 76 and 
their centering tools 73 and 74 come into operation and first move 
transversely and then longitudinally, centering each link D perfectly in 
correspondence with the respective inductor element 67. It is clear that 
the movements described for one pair of centering tools 73 and 74 are also 
identical for the other two pairs relative to each side of the apparatus 
10, in synchronism with both the pick-up 32 and the conveyor 33. 
Once centering has been effected, the retaining members 82 come into play 
and, with their ends 92, clamp each link D in contact with the respective 
plate 33a. Subsequently, the geared motor-oscillator units 50 and 55 come 
into action and the inductor elements 67 are energised. The inductor 
elements 67 are essentially U-sectioned so as to surround the upper part 
of the links D, and move towards and away from the surface of the links D 
in their circular movement, with a so-called brushing movement. During 
this brushing, the upper part of the links D are heated until they reach a 
predetermined temperature (red heat). Subsequently, the movement of the 
auxiliary frames 42 and 45 is stopped, the retaining members 82 and the 
centering tools 73 and 74 are retracted, and the conveyor 33 is advanced 
by one step. The operations described above are then repeated in exactly 
the same manner. 
At the outlet from the last inductor elements, the upper parts of the links 
D are hit by jets of water A so as to finish the hardening process. 
The choice of using several inductor elements in series results from 
reasons of increased productivity and from metallurgical reasons to 
achieve a greater depth of hardening. Indeed, in the transfer from one 
inductor element to the next, the inductance-heated surface zone (skin 
effect) transmits part of the heat obtained to the underlying metal by 
conduction so that a greater thickness of material reaches a temperature 
suitable for hardening. 
The principle of the invention remaining the same, it is understood that 
the details of realization and forms of embodiment may be varied widely, 
without thereby departing from the scope of the present invention.