Counting die cast manufactured goods

A setting unit sets data indicative of a normal shot operation of the die casting machine and a detection unit detects the operational status of the machine. A distinction unit distinguishes the coincidence of both the setting data and detected data. If the detected data are substantially equal to the setting data then the distinction unit sends a coincidence signal. A counting unit counts the coincidence signals of an injection process.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the counting of goods manufactured by a die 
casting machine. More particularly, the invention relates to an 
arrangement (apparatus and method) for automatically counting die casting 
manufactured goods. The invention automatically distinguishes goods 
produced during a "waste shot" from those produced during normal operation 
of the die casting machine. 
2. Description of the Related Art 
Die casting machines are widely used for producing goods made of aluminum 
and other metals. Die casting machines are generally operated, in one of 
three modes: a "test shot" mode, a "waste shot" mode and a "normal" mode 
during which goods are produced. A "test shot" is an operating procedure 
carried out to determine the various conditions under which the die 
casting machine will be later operated during "normal" mode operation for 
continuously producing goods which satisfy production specifications. 
The various conditions and parameters defining normal mode are determined 
by carrying out one or more test shots. For example, one condition that 
may need to be determined during one or more test shots might be the 
critical speed of a plunger during part of the injection molding process. 
For example, in the case of a two stage injection system, one or more test 
shots might be used to determine the critical speed of the plunger during 
a low speed injection process for filling a mold with molten metal. This 
is the speed required to avoid causing porosity in the die casting 
manufactured goods. Of course, this is only one example. 
Other conditions may also be determined during test shots, such as, for 
example: 
a) the speed of the plunger of injection during a low speed injection 
process; 
b) the timing of a change of plunger speed from low speed to high speed; 
and 
c) the timing for increasing the pressure of molten metal (intensification) 
and the pressure thereof, and the like. Of course other conditions may 
also be determined during a test shot. 
After operating in test mode for one or more test shots to determine 
various operating conditions, the die casting machine is operated in waste 
shot mode. One or more waste shots are carried out. Typically, waste shots 
are carried out at various times: 
during warming up of the die casting apparatus at initial start-up; 
during warming up of the apparatus after a pause in its operation; and 
when molten metal is loaded into a metal mold cavity to stabilize the 
temperature of the metal mold. 
After carrying out one or more waste shots, the die casting apparatus is 
operated continuously for some time in its normal mode to manufacture die 
cast goods. During normal mode operation, the various operating parameters 
determined during test mode operation are used. Assuming that the various 
operating parameters were correctly determined during test shots, the 
goods produced should meet design specifications. The machine is operated 
in normal mode until the desired number of manufactured goods are 
produced. Thus, it is desirable to be able to count the individual goods 
produced. 
It is known to provide a counter and a selecting switch for counting die 
cast manufactured goods. After a waste shot the selecting switch is 
manually turned on to actuate the counter. However, according to known 
practice, it is difficult to automatically count only the goods from 
normal shots because of the test shot and waste shot operations. The 
operator of a die casting machine must distinguish whether each piece of 
goods produced is from a normal shot, a test shot or a waste shot. The 
operator manually turns on and off the selecting switch to actuate the 
counter. 
Accordingly, it is desirable to provide an arrangement for automatically 
counting manufacturing goods in a die casting machine that would eliminate 
the need for this type of operator involvement. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an apparatus for 
automatically counting die casting products. 
The present invention achieves this object by providing an arrangement for 
automatically counting die casting manufactured goods. 
According to the present invention there is provided a setting unit, by the 
use of which, the operator can preset data which defines normal shot 
operation of the die casting machine. There is also provided a detecting 
unit for detecting various conditions indicative of the operation status 
of the die casting machine and comparing those various conditions with the 
data previously set via the setting unit. A distinction unit distinguishes 
coincidence of the data detected by the detecting unit and the data 
previously set by the setting unit and outputs a coincidence signal 
indicative thereof. Each time there is a coincidence, a counting unit 
increases its count by one, thereby counting the number of the goods 
produced by the die casting machine. 
Moreover, according to the present invention, there is also provided a 
method of counting die casting products. The method includes the following 
steps: 
a) setting data for a normal shot operation of the die casting machine; 
b) detecting operation if the detected data are substantially equal to the 
setting data then the distinction unit sends a coincidence signal status 
of the die casting machine; 
c) distinguishing a coincidence of the operating status detected in a shot 
operation and the data set by the setting step; and 
d) counting the number of the die casting products in the case of existence 
of coincidence between the operation status and the data set by the 
setting step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A preferred embodiment of the present invention will now be described in 
more detail with reference to the accompanying drawings. 
First, referring to FIG. 3, a presently preferred method, according to the 
present invention, for counting die casting machine manufactured goods 
will be described. The description that follows refers also to the 
apparatus shown in block diagram in FIG. 2. 
Step S10 
At step S10, data is input by the operator which specifies certain 
operating conditions. This step is the equivalent of step S01 in FIG. 1. 
In part, these conditions specify how the die casting machine should 
operate during a normal shot, i.e. during normal and continuous 
operations. These conditions can be used to distinguish normal shot 
operation from waste shot operation. Also, conditions are established for 
judging the operational status of the die casting machine. These 
conditions are decided depending upon the type of die casting machine 
being used and upon the type of goods to be manufactured. One or more test 
shots may be carried out to determine all of the appropriate conditions. 
The operator uses the setting unit 23 to set these conditions for normal 
use. These conditions are transferred to the distinction unit 25 which 
memorizes these operating conditions. 
Step S20 
Detecting unit 21 detects the operating status of the die casting machine 
and sends detection signals to distinction unit 25 during the operation 
(waste shot and normal operation) of the die casting machine. 
Step S30 
Distinction unit 25 receives signals from detecting unit 21 indicative of 
the operation of the die casting machine. Data corresponding to those 
signals are compared with data that have been previously stored in the 
setting unit 23. Distinction unit 25 determines whether or not there is 
appropriate correspondence between the data from detecting unit 21 and the 
data stored in setting unit 23. This step is equivalent to step S02 in 
FIG. 1. If the data appropriately correspond, distinction unit 25 
generates a correspondence signal that is output to counting unit 27. 
During a waste shot, operation running status is detected. Detecting unit 
21 detects the status of the die casting machine and sends it to 
distinction unit 25. During a waste shot, there will not be an appropriate 
correspondence between the data from detecting unit 21 and the data stored 
in setting unit 23. Thus, a coincidence signal will not be output to 
counting unit 27. 
However, during normal operation, there may or may not be appropriate 
coincidence, depending on whether the required operating conditions are 
being met. If the required operating conditions are not being met, 
distinction unit 25 may output an alarm signal which indicates an abnormal 
status of the die casting machine. 
Step S40 
Counting unit 27 increases its count by one when distinction unit 25 
outputs a coincidence signal which corresponds to one injection operation 
for one normal manufactured good. This step is the equivalent of step S03 
in FIG. 1. 
The count registered by counting unit 27 may be cleared when operating 
conditions are input via setting unit 23. The count registered by counting 
unit 27 corresponds to the number of manufactured goods produced. When the 
count registered by counting unit 27 reaches a desired preset value, 
counting unit 27 outputs a signal which indicates that the number of 
manufactured goods have reached the desired value. 
Step S50 
The count registered by counting unit 27 may be displayed to the user in a 
variety of ways. For example, the count could be displayed via a cathode 
ray tube (CRT), or on some other type of display, such as a printer, light 
emitting diode, or other such output device. The count can either be 
continuously displayed or displayed when desired by the operator. 
Step S60 
Steps S20 through S50, described above, are repeated until the preset 
number of manufactured goods are produced. 
Step S70 
When the count registered by counting unit 27 coincides with the preset 
value in distinction unit 25, a signal is generated by counting unit 27 
which indicates the end of production because the number of manufactured 
goods has reached the preset value. 
When the counting arrangement is constructed such that it is separate and 
apart from the die casting machine, counting unit 27 may output a signal 
which indicates that production should be ended. This signal may be 
coupled to the die casting machine and utilized by the die casting machine 
to automatically stop its operation. Of course, the counting arrangement 
could be built into the die casting machine. A similar process of 
automatically stopping the operation of the die casting machine could be 
carried out internally. 
A presently preferred embodiment of the counting arrangement according to 
the present invention is shown in FIG. 4. In this embodiment, the counting 
arrangement is implemented using a microprocessor system. The embodiment 
includes a central processing unit (CPU) 50, a read-only memory (ROM) 54, 
a random access memory (RAM) 56, a display (labeled in FIG. 4 as "DSP") 
91, a printer (labeled in FIG. 4 as "PRTR") 93 and a keyboard (KB) 31. The 
embodiment also includes pressure sensor (PR) 11, analog digital converter 
(A/DC) 58, speed detector (labeled in FIG. 4 as "SPD") 14 and counter 
(labeled "CNTR" in FIG. 4) 15. 
The operation of this embodiment will be described with reference to FIG. 
2. Detecting unit 21 of FIG. 2 is constituted by PR 11, speed detector 14 
and counter 15. Operating condition setting unit 23 is constituted by KB 
31. Distinction unit 25 is constituted by CPU 50, ROM 54 and RAM 56. 
Counting unit 27 is constituted by CPU 50 and RAM 56. Output unit 29 is 
constituted by display 91 and printer 93. 
Converter 58 is connected to CPU 50 via a bus 52 in order to input signal 
information from PR 11. A speed value from counter 15 is input to CPU 50 
via bus 52 and stored RAM 56. ROM 54 stores a control program for CPU 50. 
RAM 56 updates the count for each injection cycle (function of counter for 
manufactured goods) and temporarily stores data. 
FIGS. 5(a) through (d) show the outline structure and the major operating 
parts of a die casting machine to which the present invention is applied. 
The die casting machine shown in this embodiment is of the horizontal 
type. However, the invention is equally applicable to other types of die 
casting machines. 
The basic operating modes of the die casting machine include a pour process 
(charging process FIG. 5(a)), a low speed injection process (FIG. 5(b)), a 
high speed injection process (FIG. 5(c)), intensifying process (holding 
process FIG. 5(d)), a die opening process (not shown), an ejecting process 
(not shown), and piston 116 returning process and the like. 
The following is a brief description of one injection cycle in the normal 
operation for manufacturing die cast goods. 
As shown in FIG. 5(a), during a pouring process molten aluminum 201 in a 
holding furnace 100 is ladled out by a ladle 102 and poured into a sleeve 
108 which is constructed between a plunger 104 and a cavity 106. 
Then, as shown in FIG. 5(b), during the low speed injection process, the 
molten metal poured into sleeve 108 is injected by plunger 104 at low 
speed. A predetermined critical low speed is utilized in the low speed 
injection process to avoid porosity in the manufactured goods, resulting 
from absorption of air. Plunger 104 is driven by adding hydraulic pressure 
into injection cylinder 114 and injection piston rod 112 is pushed by the 
pressure. Then, plunger 104 is inserted into sleeve 108 via plunger rod 
110 connected to injection piston rod 112. The low pressure process is 
operated from the time t0 to t2 as shown in FIG. 6. Injection piston rod 
112 has magnetic scale 140 and non-magnetized trenches are provided with a 
fixed pitch in injection piston rod 112. Further, at the top part of 
injection cylinder 114, magnetic sensor 142 is set in order to detect the 
motion of magnetic scale 140; that is, the motion of injection piston rod 
112. In this embodiment magnetic scale 140 and magnetic sensor 142 
constitute speed detector 14 mentioned above (in this case, magnetic tape 
speed sensor). Magnetic scale 140 is set in the longitudinal direction of 
the piston rod 112. Thus, when magnetic scale 140 is moved with the motion 
of injection piston rod 112 by the hydraulic pressure, the motion is 
detected as the speed of injection speed. This is detected as speed pulses 
by the magnetic sensor SPD(P) as shown in FIG. 6. The speed is measured as 
pulse period. In other words, it corresponds to a pulse frequency. These 
pulses detected by magnetic sensor 142 are counted by counter 15. Counter 
15 is updated in a predetermined period. Thus the number of pulses shows 
the speed of that period. The output of counter 15 is stored into RAM 56 
via CPU 50. The counting speed of counter 15 is shown as SPD (c) in FIG. 
6. Pressure sensor 11 is set in injection cylinder 114 in order to detect 
the pressure in the injection process. In this embodiment a strain gauge 
type of pressure sensor is used as pressure sensor 11 and the detected 
pressure value is shown as PR in FIG. 6. The detected pressure value is 
stored into RAM 56 via converter 58 and CPU 50. 
This embodiment is based on a two stage type die casting machine. Thus the 
next process after the low speed injection process is the high speed 
injection process. In the high speed injection process beginning at t1, 
injection piston rod is moved rapidly and sleeve 108 is rapidly filled 
with the molten metal. Then cavity 106 is filled with the molten metal 
through the gate at the entrance. The characteristic of the high speed 
injection process is shown in FIG. 6 during the period of t2 through t4. 
As shown in FIG. 6 the speed SPD rises suddenly to a maximum at t3. Also 
the pressure PR rises slowly. When plunger 104 is pushed enough into 
sleeve 108, plunger 104 stops. As a result, the speed SPD goes nearly 
zero. 
After the time t4, the intensifying process starts by adding high hydraulic 
pressure into a cylinder 118 having a large diameter. After the time T1 
which is predetermined, for example, after T1=30 msec, the intensified 
pressure is held (holding pressure) during the time T2 from t5 to t6, for 
example t2=165 msec. 
After the intensifying process a die opening process and ejection process 
thereafter are operated. 
The waste shot operation is a warming-up operation so the high speed 
injection is not operated. The simplest way to distinguish a waste shot 
from normal shot is to test for the existence of the high speed injection 
process. For the first example of distinction, the process operation of 
the counting apparatus for the die casting manufactured goods is 
described. 
EXAMPLE 1 
The operator sets data as a condition to distinguish waste shots from 
normal shots. The data correspond to the level of SPD 1 in the high speed 
process of FIG. 6, which is recognized as high speed. Also, if it is 
requested that the number of manufactured goods is set, the number is sent 
at the same time to CPU 50 via KB 31. These data are stored in RAM 56. The 
distinction level SPD 1 may be any level which can distinguish high speed 
from low speed. CPU 50 clears the address in RAM 56 in correspondence with 
this setting operation. The address works as the counter (hereinafter 
referred to as "the manufactured good counter") for counting manufactured 
goods. 
Under the conditions mentioned above, when waste shot is operated, pressure 
sensor 11 inputs a pressure signal via converter 58 and speed detector 14 
inputs a signal indicative of plunger speed. Because this is a waste shot, 
the detected signal of the speed sensor does not exceed the predetermined 
distinction level and the control program stored in ROM 54 does not detect 
the high speed injection process. STEP S30 of FIG. 3 and the manufactured 
goods counter does not increase its count value. Accordingly, the number 
of manufactured goods is not increased during a waste shot operation. 
After the waste shot operation, the operator sets data indicating the 
number of manufactured goods which are desired. If necessary, the 
distinction level SPD 1 of high speed injection may be corrected and the 
data for correction is set to CPU 50 via KB 31. 
After the waste shot operation, the die casting machine is operated in a 
normal shot mode. During normal shot mode operation, CPU 50 detects that 
the speed signal changes from low speed to high speed and exceeds the 
distinction level (FIG. 3, STEP S30). Then the manufactured goods counter 
increases its count by one. The value of the manufactured goods counter is 
displayed on display 91 by CPU 50. (FIG. 3, STEP S50). When the value of 
the manufactured goods counter reaches the value originally set by the 
operator (FIG. 3, STEP S50), CPU 50 outputs the signal which shows the 
final shot for the manufactured goods. Then CPU 50 outputs the message to 
printer 93, which shows the final shot and the number of manufactured 
goods (FIG. 3, STEP S70). 
EXAMPLE 2 
In this example, the overall die casting process includes, during normal 
operation, an intensifying process. However, the intensifying process does 
not take place during waste shot operation. Thus, in this example, the 
decision of whether or not a waste shot is being carried out will be based 
on the existence of the intensifying process (rather than whether or not 
high speed injection is taking place, as in Example 1). In this case, 
pressure signal PR 2 shown in FIG. 6 is used in order to recognize whether 
an intensifying process is being carried out. When the speed of plunger 
104 exceeds the level of high speed distinction and moreover the pressure 
of molten metal exceeds the level of PR 2, CPU, 50 recognizes that a 
normal shot is operated (FIG. 3, STEP S30). The other processes of CPU 50 
are similar to those of Example 1. 
EXAMPLE 3 
In this example, the die casting process includes, in normal operation, a 
high speed injection and an intensification process. These processes are 
set by operation of a mode selection switch. Thus, in this example, 
signals from the mode switch are used to distinguish the type of process 
that is being carried out. In this example, a first "high speed on" switch 
signal is input and then an "intensification on" switch signal is input. 
Also, a normal mode selection signal is input. Furthermore, a detected 
speed signal and a detected pressure signal may be combined with these 
signals. (FIG. 3, STEP S30). To distingish one cycle from the next, a 
change of speed signal or pressure signal may be used. 
EXAMPLE 4 
In this fourth example, an increase in speed is used to distinguish a waste 
shot from a normal shot. Also, in this case one cycle of normal injection 
is recognized. 
In this example, speed transition is utilized. The operator sets speed data 
SPD 0, SPD 1, SPD 3 and SPD 4. SPD 0 shows the speed of the low speed 
process and SPD 1 shows the speed for the start point of high speed 
injection. Also, SPD 3 shows the speed for the near end point of high 
speed injection and SPD 4 is the speed of holding pressure (near zero) KB 
31 is used for setting these data and stores them to RAM 56 via CPU 50. 
Under these conditions, CPU 50 increases the count of the counter by one 
when the speed signal is detected as the level of SPD 0 first, and then 
the level changes to SPD 1 through SPD 2, over SPD 2, less than SPD 3 and 
near to SPD 4, and also the pressure of molten metal goes over PR2 which 
shows the intensifying process. (FIG. 3, STEP S30 and STEP S40). 
This results not only in the distinction of waste shot from normal shot, 
but also the recognition of the normal shot, that is, CPU 50 can recognize 
that the manufactured goods were not produced. Accordingly, if CPU 50 
detects non-waste shot, CPU 50 can recognize the matching of the speed 
transition pattern mentioned above. In such a case, CPU 50 does not count 
the number as a normal shot. Then CPU 50 judges that the process was not 
operated normally and that the goods do not have the desired predetermined 
characteristics. Further, CPU 50 may output the alarm signal by the 
detection of this status. 
EXAMPLE 5 
As the fifth example, the pressure transition data are used to to 
distinguish the manufacture of normal products. In this example, both 
speed transition and pressure transition are used to recognize the 
behavior of the die casting machine. Data PR 0, PR 1, PR 2 and PR 3 are 
used and set in the RAM 56 via CPU 50 by KB 31. PR 0 is the data for 
recognition of the low speed injection process and PR 1 is the data for 
the high speed process. PR 2 is the data for recognition of the 
intensifying process and PR 3 is the data for the holding pressure 
process. (FIG. 3, STEP S10). 
In this example, CPU 50 can distinguish waste shots from normal shots by 
means of detecting speed signals and pressure signals (FIG. 3, STEP S30) 
and can also recognize that die casting manufactured goods are produced in 
the normal operation. 
EXAMPLE 6 
This example utilizes time to distinguish operations of the die casting 
machine. Times T1 (the low speed injection time) and T2 (the high speed 
injection time) are set into RAM 56 by the operator. CPU 50 recognizes 
whether or not manufactured goods are produced in accordance with those 
times. When CPU 50 recognizes the shot which is not operated along these 
conditions, it decides that the process is not normal. In such case, CPU 
50 does not cause the count of the counter to increase. 
EXAMPLE 7 
In this example, operation of the die casting machine is distinguished by 
the use of the working characteristic curve. The working characteristic 
curve includes pressure data of molten metal and speed data as shown in 
FIG. 6. The data of the working characteristic curve is stored in RAM 56 
from KB 31 via CPU 50. CPU 50 recognizes the normal operation along the 
data which is set as the condition of the normal operation. 
In this case, the detected data change fast so that the filtered data are 
used. Also setting data is average data of the normal shots. CPU 50 can 
afford to recognize the data which is detected in the normal operation and 
also uses the filtering technique in order to discriminate the speed 
signal and the pressure signal from the instantaneous signal and noise 
signals. 
Although the embodiment described above shows examples in which the present 
invention is applied to a cold chamber die casting machine of a two stage 
injection system, it should be understood that the present invention is 
also applicable to die casting machines of different types, for example, a 
hot chamber die casting machine which is used for Zn alloy. 
Furthermore, although the embodiment is described for the structure shown 
in FIG. 4, the present invention is not limited to this structure. 
Different structures may be used. For example, a manufactured goods 
counter which is independent from CPU 50 could be used and the initial 
status of the manufactured counter is cleared and set the number of 
product by CPU 50. When CPU 50 recognizes the normal shot operation in 
each shot, the counter is increased by one. At the time when the value of 
the counter reaches the preset value, the counter generates a signal which 
indicates the end of production. 
The counting arrangement (both apparatus and method) can be built into a 
die casting machine or utilized in a separate and distinct physical 
structure. The invention is not limited to one or the other. For example, 
the counting arrangement could be built directly into the main control 
arrangement for a die casting machine. 
As described above, according to the present invention, normal shot 
operation is distinguished from the waste shot. Also an abnormal shot is 
detected during otherwise "normal" operation of the die casting machine. 
According to the present invention, operation of the die casting machine 
is measured against predetermined conditions that are desired to be met 
during normal production. Accordingly, the exact counting of the products 
of the normal production of a die casting machine can be accomplished. 
In summary, this invention provides a method and apparatus for automatic 
and exact counting of the die casting machine.