Device for automatic adjustment of die height of a press

A device for automatically adjusting die height in a press having a plurality of dies aligned in a work transfer direction includes a load pattern setting member for inputting possible load patterns, each pattern corresponding to the number of dies under load. A correction setting member is provided for inputting an amount of correction (compensation) by which the position of the bottom of the slide in each load pattern is rectified to a basic position corresponding to a basic load pattern. A pattern identifier is provided for identifying the current load pattern when the slide is at a given position. A correction controller is provided for selecting the proper amount of correction of the position of the bottom of the slide for the identified load pattern and sending a drive control signal corresponding to this amount to a slide position adjustment unit. A slide adjustment actuator is provided for actuating the unit to automatically rectify the position of the bottom of the slide at the bottom dead center of the press cycle to the basic position.

REFERENCE TO RELATED APPLICATION 
This application claims the priority of Japanese Application Serial No. 
1-272344 filed Oct. 19, 1989. 
BACKGROUND OF THE INVENTION 
The invention relates to a device for automatically adjusting the die 
height of a press having plural dies. 
FIG. 5 shows a conventional device for automatically adjusting a slide of a 
press. In the drawing, a connecting rod 1 is connected to a crank portion 
of a press crankshaft (not shown). A slide point portion 3 of the press 
links the connecting rod 1 to a slide 8. At the slide point portion 3, 
there is provided a ball or wrist pin, not shown. The connecting rod 1 and 
the slide point portion 3 are adjustably connected by an adjustment screw 
4 which is rotated by a worm wheel 5 and a worm gear 6 to adjust the axial 
spacing of the connecting rod 1 and the slide 8. 
The worm gear 6 is rotated by a drive shaft 12a, which is connected to a 
deceleration motor 11. A slide position adjustment unit 20 comprises a 
slide position setting element or means 21, a down controller 22, a slide 
adjustment actuator (e.g. button means) 23a, an up controller 24 and a 
change-over element or means 25 by which the controllers 22, 24 are 
selected. 
A device 9 for confirming that the slide 8 has reached an upper limit is 
formed as a limit switch which operates when it contacts an operator 
member 7 projecting upward from the slide point portion 3. The device 9 
operates the up controller 24 to stop the ascending slide (closing) 8 at 
the upper limit. The device 9 responds to actuation of its limit switch to 
send a signal (SPS) to the up controller 24. A device 10 for confirming 
that the slide 8 has reached a lower limit is also formed as a limit 
switch and operates when it contacts another operator member 7a projecting 
downward from the slide point portion 3, and this device 10 is adapted to 
operate the down controller 22 to stop the descending slide 8 at the lower 
limit. The device 10 responds to actuation (closing) of its limit switch 
to send a signal (SPS) to the down controller 22. 
When the limit switch of the device 9 or 10 is closed and sends the signal 
(SPS), the slide 8 is stopped by the controller 22 or 24 at either the 
upper limit or the lower limit, respectively. 
Then, if the slide adjustment button means 23a is turned ON (actuated), the 
controller 22 or 24 operates based on the value (die height) set in the 
slide position setting means 21 (which may be formed as a digital switch), 
thereby automatically stopping the slide 8 at a position corresponding to 
the set die height. 
A detector 26 for detecting the current (instantaneous) slide position, or 
a multi-rotating absolute encoder, is adapted to rotate by a drive shaft 
12b via a gear mechanism 13 which includes gears 13a and 13b. The detector 
26 comprises a reversible counter, a display, and a switch mechanism, and 
it digitally displays the instantaneous slide position. The switch 
mechanism, in accordance with Article 31 of the Japanese standards for 
structure of power press machines, sends signals HLS and LLS to prevent 
the slide from going beyond the upper and lower limits, respectively. Each 
signal is emitted upon closing of the upper or lower limit setting means 
incorporated in the switch mechanism. 
The automatic slide adjustment device according to the prior art has the 
above-described sophisticated construction. However, it cannot satisfy 
current demands for diversification in forms of production, automatic 
speed-up and highly precise production in the case of manufacturing 
various products in small quantities by one press machine or in the case 
of forming large products. 
According to the prior art, generally while the press is stopped, the slide 
is moved up and down for adjustment to the die height desired during the 
continuous running of the press. However, in a press having a number of 
dies disposed in a direction of transfer of the workpieces through the 
press, a so-called transfer press, the change in the number of dies under 
load will inevitably cause elongation of the press frame including the 
column, thereby changing the die height at bottom dead center. Thus, the 
workpieces formed by the prior art press machine during its initial 
operation, i.e. during the transition from the start of operation to the 
continuous running condition while the number of dies under load is 
continuously changing, those articles formed just prior to the end of the 
operation, i.e during the transition from the continuous running condition 
to completion, are treated as defective products. Thus, the prior art not 
only causes waste and therefore a high production cost but also creates an 
obstacle to a speed-up of the operation due to its long starting and 
ending periods. These disadvantages are particularly serious problems for 
a large press having many dies. 
It may be possible to adjust the slide manually each time there is a change 
in the number of dies under load during successive press cycles of the 
starting and completion operations. However, because the correct operation 
of the slide position setting means 21 must rely upon the human operator's 
memory, the prior art is not only complicated in operation but also likely 
to cause human error such as a simple mistake in identifying and inputting 
data relating to the dies in use, thereby possibly resulting in a failure 
of the dies. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide a device for automatically 
adjusting the die height for a press which, by merely operating the slide 
adjustment button means when the slide is at a given position, can 
automatically adjust the slide position in accordance with changes in the 
number of dies under load so as to assure that the die height at bottom 
dead center is always the same irrespective of changes in load pattern, 
thereby producing articles of a required accuracy. 
A device for automatically adjusting die height in a press having a 
plurality of dies aligned in a work transfer direction according to the 
invention includes a load pattern setting means for setting (inputting) 
possible load patterns, each pattern corresponding to the number of dies 
under load. A correction setting means is provided for setting an amount 
of correction (compensation) by which the position of the bottom of the 
slide in each load pattern input by the load pattern setting means is 
rectified to a basic slide bottom position corresponding to a basic load 
pattern. A pattern identification means is provided for identifying the 
actual load pattern at the given slide position with one of the possible 
load patterns set by the load pattern setting means. A correction control 
means is provided for selecting the proper amount of correction of the 
position of the bottom of the slide at bottom dead center of the press 
cycle, for the identified load pattern, and sending a drive control signal 
corresponding to this amount to a slide position adjustment unit. A slide 
adjustment actuator is provided for actuating the unit to automatically 
rectify the position of the bottom of the slide at the bottom dead center 
of the press cycle to the basic slide bottom position, for the identified 
load pattern. In the above constructed device according to the invention, 
the load pattern defined by the number of dies under load and the amount 
of correction for rectifying the position of the bottom of the slide in 
each possible load pattern to the basic position are predetermined, the 
load pattern being set (input) by the pattern setting means while the 
amount of correction is set by the correction setting means. 
If the press is started and then stopped to locate the slide at the given 
position (for example, the top dead center), the pattern identification 
means then operates to identify the load pattern. Subsequently, upon 
operating the press adjustment button means, the correction control means 
emits a signal corresponding to the amount of correction to the slide 
position adjustment unit, based on the identified load pattern. 
Thus, even if the number of dies under die changes during the starting or 
stopping operation, the position of the bottom of the slide is always 
adjusted automatically to the basic position regardless of the load 
pattern, simply by alternately repeating the one-process operation (one 
cycle) of the press and the operation of the press adjustment button 
means. Consequently, it is possible to always make the die height at the 
bottom dead center constant by fixing the basic position at a given die 
height. 
In summary, the invention comprises a load pattern setting means, a 
correction setting means, a pattern identification means and a correction 
control means, wherein the press start button and the slide adjustment 
button are only pushed reciprocally, whereby the slide adjustment device 
makes constant the position of the bottom of the slide at the bottom dead 
center for each load pattern. Thus, the invention can form workpieces at 
any time in a precise manner and with reduced production cost. The 
invention is most suitable for speedily producing various articles in a 
small quantity.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, the automatic adjustment device of the invention 
comprises a load pattern setting means 32, a correction setting means 33, 
a pattern identification means 34 and a correction control means 49. When 
the slide is at a given position, i.e. top dead center, the slide 
adjustment button means 23 is turned ON (actuated) to operate a slide 
position adjustment unit 20 so as to rectify the position of the bottom of 
the slide at bottom dead center in the corresponding load pattern, thereby 
enabling an automatic adjustment of the slide to a constant die height to 
be performed. 
To expand its use, the invention further includes a die code number setting 
means 30 by which an identification signal (die code number) is set 
(input) for each of the dies or group of dies used. Also included is a 
basic die height setting means 31. Reference numeral 40 in FIG. 1 
designates a press control system for the entire machine, and its 
functions include a automatic adjustment of the die height. The press 
machine, including the slide, has the same structure as that shown in FIG. 
5. 
First, the press control system 40 will be described. CPU 41 is a central 
processing unit to which ROM 42, RAM 43, a display unit 44, input ports 
46, 47, and an output port 48 are connected via buses. In the ROM 42, a 
drive control program for the entire press machine is stored. The display 
unit 44 may be a digital display or a CRT, and it displays a basic (set) 
die height, the current die height, the position of the bottom of the 
slide and the amount of correction. If a press start button 51 is 
depressed (turned ON), the press performs one pressing process (cycle), 
and the slide stops at the given position (the top dead center in the 
preferred embodiment). This is confirmed by a rotary cam switch 52. 
The load pattern setting means 32 sets (inputs) possible load patterns in 
accordance with the number of dies under load. In the embodiment, it is 
formed as a digital switch, and the set patterns are stored in the RAM 43. 
Namely, in a press having plural dies aligned in a work transfer 
direction, the number of dies under load gradually increases during the 
starting operation (at the beginning of a run) while it gradually 
decreases during the stopping operation (at the end of the run). The 
change in the number of such dies will result in a change in the 
elongation of the press column, thereby changing the position of the slide 
at the bottom of its reciprocal movement (bottom dead center) and 
consequently the die height. Accordingly, the invention defines different 
load patterns, each corresponding to the number of dies under load, and 
sets the amount of correction for the die height in each load pattern. 
Referring to FIGS. 2 and 3, the number shown encircled in the slide 8 
represents the number of dies under load. For example, 1 indicates one die 
subject to the press load. Using four dies, seven load patterns P1 to P7 
are shown. P1 and P7 are the load patterns for one die under load during 
the starting and ending operations, respectively. Similarly, P2 and P6 are 
those for two dies, and P3 and P5 are for three. Defining the elongation 
of the unloaded press frame as .lambda. the elongation for the load 
patterns P1, P2, P3, P4 are respectively .lambda.1, .lambda.2, .lambda.3, 
.lambda.4, as shown in FIG. 2, so it is apparent that the position of the 
bottom of the slide at the bottom dead center is lowest in the load 
pattern P1 while highest in load pattern P4. 
Although the numbers of dies under load in load patterns P1, P2, P3 are 
respectively the same as the numbers of dies under load in load patterns 
P7, P6, P5, the patterns are different in the positions of such dies. 
However, for the convenience of explanation, the elongation in the load 
patterns P1, P2, P3 is assumed to be the same as that in load patterns P7, 
P6, P5, respectively. 
In the disclosed embodiment, the load pattern P4 is defined as a basic load 
pattern, and thus the corresponding position of the bottom of the slide 
(as effected by the elongation of the press during the continuous running 
of the press) is defined by a basic die height DH, the setting (inputting) 
of which is effected through the basic die height setting means 31, and 
which is stored in the RAM 43. 
The correction setting means 33, which is formed as a digital switch, is 
the means for setting the amount of correction necessary to rectify the 
position of the bottom of the slide in each of the set load patterns to 
the basic slide bottom position, that is, the position of the bottom of 
the slide in the basic load pattern P4. (Alternatively, another load 
pattern may be defined as the basic load pattern.) The amounts of 
correction for the load patterns P1 to P4 are respectively the distances 
C1 to C4 shown in FIG. 2. The amounts of correction C1 to C4 are 
calculated as follows. 
EQU C1=.lambda.4-.lambda.1 
EQU C2=.lambda.4-.lambda.2 
EQU C3=.lambda.4-.lambda.3 
EQU C4=.lambda.4-.lambda.4=0 
Upon confirming by the rotary cam switch 52 that the slide 8 is at the top 
dead center, the pattern identification means 34 identifies the current 
load pattern Pn with one of the possible load patterns P1 to P7 stored in 
RAM 43. This may be done automatically by the control program stored in 
the ROM 42. However, this embodiment uses grip-detecting limit switches 
LS1 to LS4 which are adapted to operate when the workpieces are held by 
grip fingers mounted to the feed bars for the respective dies, and the 
load pattern is determined on the basis of the combination of limit 
switches which detect the workpieces. For example, the load pattern is 
identified with P4 if all the four limit switches are closed. 
When the slide adjustment button means 23 is turned ON or actuated, the 
correction control means 49, which in this embodiment includes the CPU 41, 
selectively reads out from the RAM 43 the proper amount of correction for 
the identified load pattern, and emits a corresponding signal as a drive 
control signal to the slide position adjustment unit 20. 
Basically, the slide is controlled to move by the amount of correction Cn 
shown in FIG. 2. But because the number of dies under load gradually 
increases or decreases, the correction control means 49 is adapted to emit 
a drive control signal (U for the upward movement or D for the downward) 
corresponding to the difference between the position of the bottom of the 
slide in the current load pattern and the rectified position of the bottom 
of the slide in the former load pattern. In detail, the signal U1, 
corresponding to the load pattern P1, is the signal for moving the slide 
up by a distance equal to the amount of correction C1, as shown in FIG. 3. 
As the correction C1 is already effected, a drive control signal D2, 
corresponding to the load pattern P2, for moving the slide down by the 
amount C2-C1 (.lambda.1-.lambda.2) will be sufficient to correct the slide 
position for the load pattern P2. Consequently, in response to the signal 
D2, the slide position adjustment unit 20 should move the slide down by 
the distance corresponding to the difference between C2 and C1 (C1-C2). 
Similarly, signals D3 and D4 are provided for signaling the unit 20 to 
move the slide down by distances corresponding to the differences (C2-C3) 
and (C3-C4), respectively. For the same reason, the load patterns P5 to P7 
during the ending operation will lead to signals U5 to U7, respectively, 
for moving the slide upward. 
Referring to FIG. 3 illustrating the starting to ending operations, the 
dotted line indicates the uncorrected position of the bottom of the slide 
at bottom dead center while the full line indicates the corrected one. As 
is the case with FIG. 2, the number of dies under load is proportional to 
the elongation as follows: 
EQU .lambda..sub.2 =2.lambda..sub.1 
EQU .lambda..sub.3 =3.lambda..sub.1 
EQU .lambda..sub.4 =4.lambda..sub.1 
As is described above, the correction control means 49 reads from the RAM 
43 the amount of correction C1 to C4 set (input) by the means 33 and 
performs arithmetic calculations based on the program stored in the ROM 42 
to emit signals U1, D2, D3, D4, U5, U6 and U7 at the appropriate times 
following corresponding pressing cycles. It may be possible, however, to 
pre-calculate the substantial distances of slide movement corresponding to 
said signals, input the distances through the correction setting means 
based on such calculations, and output the calculated amounts of 
correction (U1, D2, D3, D4, U5, U6, U7). 
Although the slide position adjustment unit 20 of the invention is 
basically the same as the structure shown in FIG. 5, it further includes a 
select switch, not shown, and is controlled by the signals (Un, Dn) from 
the correction control means 49 if the switch is selected for automatic 
adjustment. In other words, the slide adjustment button means 23a in FIG. 
5 showing the prior art is for manual adjustment while that of the present 
invention is for automatic adjustment. The slide adjustment button means 
23 of the invention may be also used for manual adjustment. 
As shown in FIG. 1, the slide adjustment button means (actuation means) 2 
of the embodiment comprises an up button 231 and a down button 232, each 
incorporating a lamp (lamp 233 and lamp 234, respectively). When it is 
confirmed by the signal from the rotary cam switch 52 that the slide is at 
the given position, the CPU 41 lights the lamp 233 if the processed signal 
is for the upward signal Un, while it lights the lamp 234 in case of the 
downward signal Dn. Namely, before the automatic adjustment of the slide, 
the lighted lamp makes the operator aware again of whether an upward or 
downward movement is required and informs him which button should be 
pushed to actuate the slide position adjustment unit 20. The lamp flickers 
when the corresponding switch is in an operable condition, and it turns 
full on when the slide adjustment is completed. The slide adjustment 
button means 23 may be used also for manual adjustment as aforementioned 
or may omit the flickering operation. The program for automatic adjustment 
of the die height, as shown in FIG. 4, is stored in the ROM 42. 
Further, in the illustrated embodiment the die number setting means 
provides means to cope with a change in the basic die height at a time of 
exchanging one group of dies for another corresponding to a change in the 
type of products to be formed. In other words, each group of dies used 
simultaneously, for which the basic die height, the load patterns and 
corresponding amount of correction are defined, has the same die number 
(identification number). 
Next, the operation of the apparatus according to the invention will be 
described. Firstly, the setting (inputting) of data will be described. The 
die number (identification number) for the dies to be simultaneously used 
is set (input) in the die number setting means 30, and the basic die 
height is set (input) in the basic die height setting means 31. The die 
height for the load pattern P4, which has the greatest number of dies 
under load, is defined as the basic die height DH. 
Subsequently, the pattern P1 is set (input) in the load pattern setting 
means 32, and then the corresponding amount of correction C1 is set 
(input) in the correction setting means 33. For patterns P2 and P3, the 
setting of the amount C2 and C3 is similarly effected. The correction for 
pattern P4 is zero. The correction data C5, C6, C7 stored for patterns P5, 
P6, P7 is automatically effected based on the data input for patterns P1, 
P2, P3. 
The automatic adjustment of the die height will now be described with 
reference to FIGS. 1 and 4. A start button 51 for the press is pushed ON, 
whereupon the press performs a one-process operation (one cycle 
corresponding to, for example, a single reciprocal movement of the press), 
and the slide stops at the top dead center. Completion of the one-process 
operation is confirmed by a signal from the rotary cam switch 52 (see FIG. 
4, Step 10). During this one-process operation, one workpiece is fed in 
the transfer direction to the first die. This workpiece is held by grip 
fingers mounted to a feed bar (not show in the figures). 
Thus, the grip-detecting limits switch LS1 turns ON, whereby the change in 
the load pattern is detected (Step 12). Subsequently, the load pattern 
identification means 34 identifies the load pattern to be pattern P1 (Step 
14). 
At this time, the CPU 41 of the control system 40 reads out the correction 
C1 for the load pattern P1 based on the program for automatic adjustment 
of the die height stored in the ROM 42 (Step 16), and, at the same time, 
the CPU 41 processes the data in RAM 43 to calculate the distance by which 
the position of the bottom of the slide is to be rectified and outputs the 
corresponding signal U1. Then it flickers the lamp 233 so as to inform the 
operator of the direction which the slide must be adjusted and also that 
the slide is now ready to be adjusted. Thereafter, the slide adjustment 
button means 23 (231) is turned ON by the operator (Step 18), whereupon 
the signal U1 is sent via the output port 48 to the slide adjustment unit 
20 (Step 20). 
Then, the slide adjustment unit 20 moves the slide from the condition 
indicated by the dotted line to that shown by the full line in the 
position of FIG. 3 corresponding to the load pattern P1. Consequently, the 
die height for the pattern P1 has been automatically adjusted so that at 
bottom dead center, the slide bottom will reach the basic die height DH, 
whereupon the flickering lamp simultaneously adopts a fully lighted 
condition to indicate completion of the adjustment. 
Thereafter, if all adjustments to the position of the bottom of the slide 
required during a run of workpieces have been made, the procedure ends 
(Step 22). Otherwise, the procedure will start again from the Step 10, 
followed by the pushing by the operator of the press start button 51 and 
the slide adjustment button 23 231, 232), whereby the position of the 
bottom of the slide at bottom dead center (the die height) is adjusted for 
the load patterns P2, P3, P4 and similarly for the load patterns P5, P6, 
P7 which belong to the ending operation of the press. 
The embodiment comprises the pattern setting means 32, the correction 
setting means 33, the pattern identification means 34 and the correction 
control means 49 (including the CPU 41), wherein, upon operating the slide 
adjustment button means 23 (231, 232), the position of the bottom of the 
slide at the bottom dead center in each load pattern is automatically 
rectified to the basic die height by the slide position adjustment unit 
20. Thus, even the workpieces run through the press during the starting 
and stopping operations can be formed into highly precise products, 
thereby reducing the production cost. This will directly speed up the 
process and improve productivity. The invention is very useful for a press 
by which a small quantity of various workpieces are pressed (inevitably, 
this type of press must often repeat the starting and stopping operations) 
or a press by which large-sized workpieces are pressed. 
Other advantages of the invention are that the correction control means 49 
may also serve for controlling the press drive, and that the slide 
position adjustment unit 20 does not require much modification from the 
conventional structure. Further, the load pattern identification means 34 
comprises such grip-detecting limit switches LS that are in any case 
structurally required for the transfer press. Thus, the present invention 
will produce low-cost but high-precision articles. 
Because the slide adjustment button means 23 has two buttons 231 and 232 
for actuating upward and downward movement and comprises lamps 233 and 234 
to inform the operator of the current condition, much safer and surer 
operations can be performed. Additionally, the provision of the die number 
setting means 30 enables automatic adjustment to the constant die height 
to be performed without the necessity of re-setting the basic die height 
when one or more dies are exchanged. This improves the usability of the 
invention when the press is used to produce a variety, but a small 
quantity, of articles. 
Still further, because the invention permits the basic die height and the 
amount of correction for each load pattern to be easily reset, a trial 
pressing operation can be performed to obtain the practically optimum die 
height. Moreover, since the amount of correction is stored as fixed data 
in RAM 43, the invention does not require this data to be newly input and 
thus eliminates human errors incidental thereto. 
It will be understood that the above description of the present invention 
is susceptible to various modifications, changes and adaptations, and the 
same are intended to be comprehended within the meaning and range of 
equivalents of the appended claims.