Dimension indicator for sheet-metal folding or shearing machine tools

This dimension indicator for sheet-metal folding, bending or shearing machine tools comprises a measuring apparatus capable of displaying the distance from the adjustable stop member provided for positioning the workpiece to a reference plane. The device comprises structure for correcting the consequence of a displacement of the reference plane, in the form of a mechanical device coupled to the machine adjustment member and adapted to act directly or indirectly upon one of the component elements of a coupling or a data transmission disposed between the member controlling the stop member and the measuring apparatus, so as to actuate this apparatus.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to dimension indicators adapted for use in 
sheet-metal working machine tools, namely, sheet-metal shaping, folding or 
shearing machine-tools. Devices of this type comprise a measuring 
apparatus capable of displaying the distance of the adjustment stop for 
positioning the metal plate or sheet on the machine in relation to a 
reference plane such as the folding or shearing plane. 
As a rule, in a machine of the type concerned, the movement of the 
positioning stop member is controlled by a generally double screw-and-nut 
mechanism. In this case, the stop member is rigid with a pair of nuts held 
against rotation and engaged by a pair of rotary drive screws. Thus, it is 
only necessary to control the rotation of these screws in one or the other 
direction for moving the positioning stop member forwards or backwards, as 
required. To this end, one of said screws is actuatable by means of a 
drive motor or a manual control member, for example a crank handle, and 
the other screw is operatively connected to said one screw through 
suitable mechanical coupling means. 
Under these conditions, the measuring apparatus of the dimension indicator 
may consist of a mechanical or electronic counter controlling the 
movements of rotation of one of the screws driving the positioning stop 
member. In this case, the drive or transmission ratio is such that the 
data displayed by the counter show the actual value of the movement 
accomplished by the positioning stop member. Of course, a calibration is 
required, which consists in resetting the counter when the positioning 
stop member lies in the reference plane corresponding in general to the 
sheet bending or shearing plane. 
However, for technological reasons, it may become necessary to change the 
position of the reference plane afterwards, and this obviously involves 
another calibration. For instance, in plate shears the play between blades 
must be modified as a function of the thickness of the plate to be cut, 
thus making it necessary to change the position of the reference plane 
with respect to the stop position. 
Therefore, to preserve the efficiency of the dimension indicator under all 
circumstances, the operator must calibrate the machine-tool each time a 
change occurs in the play between the blades. Now, the same problem arises 
in the case of a folding machine when the setting thereof is modified. 
SUMMARY OF THE INVENTION 
It is therefore the essential object of the present invention to provide a 
dimension indicator for machine-tools of the type broadly mentioned 
hereinabove, this dimension indicator being so constructed that the data 
displayed thereby are reliable even after the position of the reference 
plane following the adjustment of the operation of the corresponding 
machine has been modified. To this end, this device is characterized 
essentially in that it comprises a system for correcting the effect 
produced by the shifting of the reference plane, this system comprising 
mechanical means coupled to the machine adjustment means and adapted to 
act directly or indirectly upon one of the elements of the coupling means 
or data transmission means provided between the positioning stop control 
member and the measuring apparatus, so as to eventually set this measuring 
apparatus. 
According to an advantageous form of embodiment of the present device, the 
correction system thereof comprises a lever pivoted about a fixed axis and 
having one end operatively connected through a link mechanism to the 
rotary shaft of the machine adjustment member, the opposite end of said 
lever being connected to the coupling means or data transmission means 
inserted between the positioning stop control member and the measuring 
apparatus. 
However, this connection system can be embodied in many different ways 
without departing from the basic principles of the invention, notably as a 
function of the type of measuring apparatus incorporated in the dimension 
indicator, this measuring apparatus consisting preferably and 
advantageously of a mechanical or electronic counter. 
Various possible forms of embodiment of the device of this invention will 
now be described by way of illustration with reference to the attached 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The plate shears illustrated in FIG. 1 are of the type in which the top 
blade supporting beam is movable in a vertical plane, the play between the 
top and bottom blade being adjustable by modifying or shifting the beam 
guide members. Otherwise, the plate shears may advantageously be similar 
to one of the many known machines of this type. 
The plate shears comprise a table 1 rigid with two opposite lateral flanges 
2 forming an integral part of the frame structure of the machine. The 
flanges 2 also carry a fixed beam 3 for supporting the fixed or bottom 
blade 4 of the machine. The other or movable top blade 5 of the machine is 
carried by a movable beam 6 driven and guided in a known fashion. 
Therefore, the movable or top blade beam 6 is carried by a pair of movable 
vertical uprights 7 underlying the two side edges of beam 6 and lying 
therefore against the flanges 2 of the frame structure. The bottom ends 8 
of these uprights bent to a "J"-like configuration are responsive to the 
outer or operative end of a control actuator or cylinder 9. 
Each lateral upright 7 is guided on one side by two pairs of rollers 10 and 
11, respectively, with the rollers of one pair underlying those of the 
other pair. On the opposite side, a simple presser roller 12 responsive to 
one or a plurality of thrust springs is provided. Each upper guide roller 
10 is rotatably mounted about an eccentric disc 13 which, when rotated 
about its axis, permits of shifting the line of contact between the guide 
roller 10 and the registering face of the corresponding upright 7. Now, it 
is this shift that enables the play existing between the two blades 4 and 
5 of the shearing machine to be adjusted as a function of the thickness of 
the plate T to be cut. 
The control eccentric 13 is rigid with a control shaft 14 provided at one 
end with a crank handle 40' or any other suitable drive member. Thus, by 
rotating the eccentric 13 about its axis the operator can adjust the play 
between the two blades 4 and 5. 
On the other hand, the machine comprises an angle-iron or like section 16 
extending horizontally behind the cutting plane of the machine and adapted 
to act as a stop member for properly positioning the plate T to be cut. 
For this purpose, this section member 16 is movable towards or away from 
the blades and its position is adjustable. To this end, the stop member 16 
carries a pair of nuts 17 held against rotation and engaged by 
corresponding rotary driving screws 18. One screw 18 is adapted to be 
rotated by means of a suitable mechanism or a motor. In the example 
illustrated, a manually operated driving mechanism is provided, which 
comprises a rotary shaft 19 provided with a control crank handle 20 and 
having its opposite end operatively connected to the corresponding screw 
18, for example through a cogged belt 21 passing over matching pulleys 22, 
23 carried by the drive shaft 19 and screw 18, respectively. 
The other screw 18 (not shown in the drawings) is operatively connected 
through a suitable coupling mechanism (not shown) to the first screw. 
Thus, rotating the shaft 19 in one or the other direction will move the 
positioning stop member 16 towards or away from the blades 4, 5. 
A dimension indicator according to this invention is associated with this 
plate positioning system and comprises a measuring apparatus capable of 
displaying the distance measured from the adjustable stop member to a 
reference plane, for example the shearing plane. 
In the example illustrated in FIG. 4, this measuring apparatus comprises a 
mechanical counter 24 having its input shaft 25 coupled to the shaft 19 
controlling the adjustable positioning stop member via a cogged belt 26 or 
a transmission chain passing over pulleys or sprockets 27, 28, rigid with 
said shafts, respectively. 
However, according to the essential object of the present invention, the 
dimension indicator comprises means for correcting the effect produced by 
the shifting of the reference plane; more particularly, in the present 
example the cutting plane will be shifted as a consequence of a change 
occurring in the play contemplated between the blades 4 and 5. To this 
end, the correcting means are adapted to shift the zero of the measuring 
counter 24 in one or the other direction, as required. 
In the example described herein, this correction system comprises a lever 
29 fulcrumed to shaft 19 and having one end operatively connected to the 
shaft 14 controlling the adjustment of play between said blades 4 and 5, 
for example through a rod 30 and a crank arm 31. The opposite end of this 
lever 29 carries a pair of pulleys 32 over which the belt 26 is passed. 
Besides, these pulleys are adapted to tension the two spans 26a and 26b of 
belt 26. 
This dimension indicator operates in the normal way. In fact, when the 
angle-iron 16 constituting the plate positioning stop member is moved by 
rotating the drive shaft 19, the input shaft 25 of the counter is rotated 
by means of said belt 26. Now the drive ratio is such that the data 
displayed by this counter correspond to the distance from the positioning 
stop member 16 to the reference plane, namely the cutting plane. 
However, if as a consequence of the change occurring in the play between 
blades 4 and 5 the position of this cutting plane were shifted, the 
correction means provided in the present device would automatically 
compensate the shift resulting therefrom. In fact, in this case the 
rotation of shaft 14 controlling the adjustment of the play between the 
shearing blades will also control the pivoting movement of lever 29 in the 
corresponding direction, thus causing the counter input shaft 25 to 
rotate. Thus, if lever 29 is caused to pivot in the direction of the arrow 
F (FIG. 4), the two belt tension pulleys 32 will move upwards and the 
upper span 26a will be elongated while reducing the length of the lower 
span 26b, so that pulley 27 and the counter input shaft 25 rigid therewith 
will rotate. 
Of course, the dimensions of the pulleys and distances between centers 
should be properly calculated so that the elongation of the upper helt 
span 26a will be equal to the reduction in length of the lower span 26b, 
in order to keep the belt 26 tight while causing a slight rotation of 
pulley 27 to ensure the desired shifting of the zero position of counter 
24. Of course, when the lever 29 is pivoted in the opposite direction the 
counter's zero is shifted similarly but in the other direction. 
Therefore, with the correction system provided in the present dimension 
indicator the operator is not compelled to calibrate the device each time 
the reference plane is shifted as a consequence of a change brought in the 
clearance between the two blades. 
FIGS. 5 and 6 illustrate two different forms of embodiment of the device of 
this invention. 
In the case illustrated in FIG. 5, the measuring apparatus of the device 
consists likewise of a mechanical counter 24a. However, this counter is 
driven through a flexible or Bowden cable 33 having its opposite end 
rigidly connected to a pinion 34 in constant meshing engagement with a 
driving pinion 35. This driving pinion 35 is carried by the screw rod 18 
the rotation of which controls the movement or shift of the plate 
positioning stop member 16 fitted to the machine. Thus, when the screw rod 
18 is rotated, the counter 24a is driven with a ratio such that the data 
displayed by the counter will correspond to the distance measured between 
the movable stop member 16 and the reference plane. 
In this specific form of embodiment of the device, the correction means 
provided for compensating the shifting of this plane comprises as in the 
preceding examples of a pivoting lever 29a having one end coupled to the 
shaft 14 controlling the adjustment of the clearance between blades 4 and 
5, this coupling consisting of a rod 30 and a crank arm 31. The lever 29a 
is fulcrumed about the screw rod 18 and its opposite end supports a pinion 
34 rigid with the Bowden or like cable 33 driving the counter 24a. 
Under these conditions, any pivotal movement of lever 29a in one or the 
other direction, as a consequence of a rotation of drive shaft 14, is 
attended by a change in the position of pinion 34 about the outer 
periphery of driving pinion 35. Now, since the two pinions are in constant 
driving engagement with each other, this movement will be attended by a 
rotation of pinion 34 in one or the other direction and therefore by a 
corresponding shifting of the zero position of counter 24a. Thus, the 
result obtained is exactly the same as in the preceding example. 
In the other modified structure illustrated in FIG. 6, the measuring 
apparatus of the dimension indicator comprises an electronic counter (not 
shown) coupled via electric conductors 36 to a pulse pick-up mounted to 
the end of the rotary screw 18 controlling the plate positioning member 
16. This pulse pick-up may consist for example of a photocell 37 
associated with a light source, these two elements being disposed on 
either side of the outer peripheral marginal portion of a disc 38 rigid 
with said screw 18 and having a circular row of apertures formed therein. 
Thus, the cell 37 will pick up the pulses delivered by this disc during 
its rotation, whereby the electronic counter will be capable of displaying 
the distance measured between the positioning stop member 16 and the 
reference plane. 
The correction means contemplated in this device comprise as in the 
preceding case a pivoting lever 29b having one end coupled through a rod 
30 and a crank arm (not shown) to shaft 14 controlling the clearance 
between the two blades of the shearing machine. This lever 29b is 
pivotally mounted on the screw rod 18 and its opposite end supports the 
cell 37 of the pulse pick-up. Therefore, this cell 37 will take different 
angular positions during the movements of lever 29b. 
Now, this pivotal movement may take place in either direction, each time 
the shaft 14 provided for adjusting the clearance between the blades 4, 5 
is actuated. Therefore, this movement is attended by a corresponding 
change in the position of cell 37, and consequently by a shift in the zero 
position of the electronic counter associated therewith. 
However, it is clear that the various forms of embodiment described 
hereinabove with reference to the attached drawings should not be 
construed as limiting the scope of the invention, since many other 
modifications may be brought thereto without departing from the basic 
principles of the invention, as will readily occur to those conversant 
with the art, notably as a function of the type of measuring apparatus 
incorporated in the device and also of the coupling means contemplated 
between this apparatus and the member controlling the movement of the 
plate positioning stop member 16. 
In these various cases, it is only necessary and sufficient that the 
kinematic transmission means provided in the correction system be 
substantially linear ones, but this requirement is easily met since the 
movements involved are extremely short. 
Besides, it will be seen that the dimension indicator according to this 
invention can be fitted to plate shearing or folding machines of various 
types. Thus, the device according to the instant invention is applicable 
to plate shears of a type other than the one shown diagrammatically in 
FIG. 1. On the other hand, FIG. 2 illustrates in fragmentary section a 
shearing machine of different construction provided with the device of 
this invention. 
In this plate shearing machine, the beam 6a supporting the movable or top 
blade 5a is guided in fixed vertical guideways 39 and the clearance 
between the pair of cooperating blades is adjusted by moving a table or 
beam 1a supporting the fixed or bottom blade 4a. To this end, the table 1a 
is mounted for horizontal forward and backward reciprocation on the fixed 
beam 3a of the plate shears and the movement thereof may be controlled by 
means of adjustment screws 40. 
The mechanism controlling the adjustable plate-positioning stop member 16a 
is the same as that incorporated in the plate shearing machine illustrated 
in FIG. 1. In fact, this stop member carries a pair of nuts 17a held 
against rotation and engaged on rotary screw rods 18a, one of which is 
rotatably driven from a motor or a suitable mechanism. In the example 
illustrated, a control mechanism comprising a shaft 19 rigid with a crank 
handle 20 and coupled to the relevant screw rod 18a by means of a belt 21 
is provided. This mechanism is associated with a dimension indicator 
proper comprising a correction system according to the present invention. 
This device may comprise one of the different forms of embodiment 
illustrated in FIGS. 4, 5 and 6. 
Therefore, in either case, the device comprises a pivoting lever 29 (or 
29a, 29b, respectively) having one end adapted, during its angular 
movement, to shift the zero position of the corresponding measuring 
apparatus. The other end of this lever is operatively connected to the 
mechanism provided for adjusting the clearance between the two blades. 
However, in the specific case of the plate shears illustrated in FIG. 2, 
the coupling means differ from those provided in the machine shown in FIG. 
1. More particularly, the relevant end of the two-armed lever 29 (or 29a, 
29b) is coupled via a pair of rods 30a, 42 to the movable table 1a to 
which the bottom or fixed blade 4a is fastened. The pair of rods 30a and 
42 themselves are interconnected by means of a bell-crank lever 41 
fulcrumed to a fixed pivot pin 46, as better seen in FIG. 7. 
Thus, any translation of table 1a in one or the other direction for 
modifying the clearance between the blades is attended by a pivotal 
movement of lever 29 (or 29a, 29b) in the corresponding direction. This 
involves automatically a shift of the zero position of the measuring 
apparatus of the dimension indicator. 
FIG. 3 illustrates another type of shears equipped with the dimension 
indicator according to this invention. In this case, the machine comprises 
a movable beam 6b provided with a pair of side flanges 43 fulcrumed to a 
pair of eccentric trunnions 44. Since the fixed blade 4b is carried by a 
beam 3b having a fixed position, the clearance between the blades can only 
be altered by rotating the trunnions 44 about their axes to move the top 
blade 5b towards or away from the fixed blade 4b. 
The mechanism controlling the positioning stop member 16b of this shearing 
machine is the same as that disclosed hereinabove. Therefore, it comprises 
a drive shaft 19 adapted to rotate one of the control screw rods 18 via a 
belt 21. 
This mechanism is associated with a dimension indicator provided with a 
correction system capable of compensating the effect produced by a shift 
of the reference plane. As in the preceding example, this correction 
system comprises a pivoting lever 29 (or 29a, 29b) having one end adapted, 
through its movement, to shift the zero position of the measuring 
apparatus of the relevant dimension indicator. The other end of lever 29 
(or 29a, 29b) is coupled to the mechanism controlling the adjustment of 
the clearance between the two blades of the machine. 
In the present case, this coupling comprises a rod 45 providing a suitable 
connection between the lever 29 and the eccentric trunnions 44 controlling 
the adjustment of the clearance between the two blades, said rod being 
operatively connected to said lever 29 by means of a bell-crank lever 41b 
fulcrumed to a fixed pivot pin 47 as better seen in FIG. 8. Thus, the 
arrangement is such that when said eccentric trunnions 44 are rotated in 
one or the other direction to change the clearance between the machine 
blades, the lever 29 is pivoted in the corresponding direction, thus 
producing the proper shift of the zero position of the measuring apparatus 
incorporated in the dimension indicator. 
But as already explained in the foregoing, the device of this invention may 
be embodied in many other ways, notably as a function of the type of 
machine to which it is to be fitted, and also of the specific nature of 
the measuring apparatus contemplated for displaying the position of the 
plate positioning stop member and also of the transmission means provided 
between the measuring apparatus and the plate positioning stop member 
control mechanism. Thus, in the case illustrated in FIG. 4, the input 
shaft of counter 24 is coupled to shaft 19 controlling the mechanism for 
moving the stop member of beam 16, but it would not constitute a departure 
from the basic object of this invention to couple said input shaft to one 
of the screw rods 18, and in this case the correction system would be 
modified accordingly. This is illustrated on the other hand in FIG. 5, 
showing that the Bowden or like cable 33 could as well be attached to the 
drive shaft 19 instead of being connected to screw rod 18. Similarly, in 
the example shown in FIG. 6, the pulse detector could be mounted on the 
shaft driving the screw 18 instead of being mounted directly on this rod 
18. 
Finally, it will readily occur to those skilled in the art that the device 
according to the instant invention could be fitted to all plate-working 
machine tools and not only to plate shears. Thus, the dimensions indicator 
of this invention could be mounted on plate shaping machines such as 
bending presses and folding presses as well.