JPH0857430A - Weight inspection apparatus - Google Patents

Abstract

PURPOSE: To provide the title apparatus discriminating whether or not a molded product is good by measuring the wt. of a resin molded product in connection with an injection molding cycle. CONSTITUTION: A belt conveyor 11 is arranged under an injection mold 6 and the housing molded by the mold 6 falls by the opening of the mold 6 to be carried to a wt. inspection apparatus 13 by the belt conveyor 11 and the wt. thereof is measured by the wt. inspection apparatus 13 to be compared with a preliminarily stored reference wt. When the measured wt. is within a predetermined tolerance value with respect to the reference wt., the molded product is judged to be good to be allowed to fall to a good product box 17. When the difference between the measured wt. and the reference wt. is the predetermined tolerance value or more, the molded product is judged to be inferior to be put in an inferior product box 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight inspection device for measuring the weight of a molded product molded by injection molding and determining the quality of the molded product based on the measurement result.
In particular, the present invention relates to a weight inspection device that can be favorably applied when the weight of a molded product is relatively light, such as several grams to several hundreds of grams. More specifically, the present invention relates to a weight inspection device suitable for determining quality of a resin molded product such as a connector housing for a wire harness.

[0002]

2. Description of the Related Art When a resin molded product is produced using an injection molding machine, sometimes a shortage of resin material called "short shot" occurs. The short shot, which is an insufficient filling of this material, evacuates the air inside the mold at the time of filling when the molten resin material does not reach the entire mold due to the influence of temperature conditions, pressure conditions, etc. This occurs when the air vent hole for the device is blocked. When a short shot occurs, a chipped portion occurs in the resin molded product, resulting in a defective product. Such defective products are various, from very few chips that are very close to non-defective products to those that have large defects.

By the way, it is difficult to eliminate the short shot and to eliminate the defects of the resin molded product with the current structure and technology of the injection molding machine. Even if the injection molding machine is excellent, a short shot occurs at a rate of about once every several thousand to tens of thousands of molding operations. Further, when the resin molded product has a small and complicated shape such as a connector housing for a wire harness, the molding die is naturally complicated and many small protruding pins and the like exist. As the molding operation is repeated, a small pin in the mold may be broken and attached to the housing, which is a molded product. If the pin breaks above,
After that, all the molded products made by the mold become defective.

Due to such circumstances, it has been conventionally inspected whether the molded resin molded product is a good product or a defective product. For example, in the process of molding a connector housing for a wire harness, the molded housing is inspected by human eyes to determine whether it is a good product or a defective product.

[0005]

The quality inspection of a molded product by the human eye sometimes causes oversight, and it is difficult to obtain a reliable inspection result. In particular, as described above, the proportion of defective products caused by short shots is about once per several thousand to tens of thousands of molding operations, so most molded products are non-defective products, and occasionally Defective products are mixed in it. Therefore, it is impossible for the inspector to find all the defective products that occur only occasionally without oversight.

Further, if it is attempted to judge the quality of continuously molded products without delay, a large number of inspectors are required. On the other hand, in the inspection method that does not judge the quality of the molded product immediately after molding, if the defective product is caused not by the short shot but by the pin breakage in the mold as described above, a large number of moldings are performed. You are forced to generate defective products. Furthermore, since the rate of occurrence of defective moldings is very low, defective moldings cannot be reliably detected by the method of performing an unannounced inspection on some of all molded products.

As described above, conventionally, there has been no technique capable of appropriately determining the quality of a molded product. The present invention
It was made under such a background, and one of the purposes is to provide the apparatus which can determine whether a molded article is a good article or a defective article in a short time using a mechanical device.

Another object of the present invention is to measure the weight of a plurality of molded products simultaneously molded by a pair of metal molds, and if there is a possibility that defective products are mixed in the molded products. , To provide a device capable of detecting it. Still another object of the present invention is to, when there is a possibility that a defective product is contained in a large number of simultaneously molded products, take out the simultaneously molded product separately from other molded products. It is to provide a device that can do this.

[0009]

First, the technical background until the completion of the present invention will be described. The inventor of the present application first focused on whether or not the quality of a resin molded product can be determined by measuring the weight of the molded product. When the molded product to be judged as good or bad is, for example, a wire harness connector housing, a short shot causes a defective product in which a part of the housing is slightly chipped as shown in FIG. 12, for example. In order to reliably detect such defective products, a highly accurate weight measuring machine is required. For example, if the housing weight is 10 g, 0.01-
A weighing machine capable of weighing 0.001 g is required. Such highly accurate weight measurement is possible by using an electronic balance.

By the way, the resin molded article has hygroscopicity,
A slight change in weight occurs over time after molding. Therefore, in order to correctly measure the weight of the resin molded product, it is necessary to measure the weight immediately after molding. In other words, continuously in the molding process line by the injection molding machine,
It is desired to provide a weight measuring step for measuring the weight of the molded product.

However, a highly accurate electronic balance is vulnerable to vibrations and shocks and is easily affected by wind. Therefore, it is difficult to accurately measure the weight by the electronic balance simply by arranging the electronic balance continuously on the molding process line. Further, when the weight of the molded product actually molded by the injection molding machine is measured, as will be described later in detail, even if the product is a good product, the weight changes while the molding operation is repeated. As a result of actual measurement, it was found that the change in the weight of this molded product was wavy in a predetermined cycle. Therefore, it was found that the quality of the molded product cannot be accurately determined by the method of simply comparing the molded product with a fixed fixed reference value. Therefore, as will be described later, the inventor of the present application has completed an invention that can correctly determine whether a molded product is a good product or a molded product may be a defective product based on a newly devised reference value.

According to the first aspect of the present invention, there is provided a device for discriminating a molded product molded by injection molding based on the weight of the molded product. The weight of the molded product molded by one injection molding operation is measured. For measuring the weight of the molded article, comparing the weight of the molded article measured by the weight measuring means with a predetermined reference weight, and outputting the difference, and the allowable value of the difference output from the comparing means. If it is within the range, the molded product is determined to be a good product, and if the difference value exceeds a predetermined allowable value, the molded product is determined to be a defective product. And a weight inspection device.

According to a second aspect of the present invention, in the weight inspection apparatus according to the first aspect, the injection molding operation is performed once.
A plurality of molded products having the same shape are simultaneously molded, and the weight measuring means measures the total weight of the plurality of molded products molded at the same time. Claim 3
The described invention is the weight inspection apparatus according to claim 2,
If the difference value output from the comparing means is within a predetermined tolerance value, the determining means determines that all of the plurality of weight-measured molded products are non-defective, and the difference value has a predetermined tolerance value. If it exceeds, it is determined that there is a possibility that a defective product may be included in the plurality of molded products whose weight has been measured.

The invention according to claim 4 is the invention according to claims 1 to 3.
In the weight inspection device according to any one of 1, the injection molding operation is continuously and sequentially repeated, the weight inspection device,
Measures the weight of a molded product that has been molded by one injection molding operation and is operated in conjunction with the injection molding operation until the molded product is molded by the next injection molding operation. It is characterized in that the discrimination is performed based on the above.

The invention according to a fifth aspect is the first to the fourth aspects.
The weight inspection device according to any one of 1 to 3, further comprising a sorting unit that distinguishes the molded product according to the determination result of the determination unit. The invention according to claim 6 is the weight inspection apparatus according to any one of claims 1 to 5, further comprising a storage means, and the reference weight is stored in the storage means.

According to a seventh aspect of the present invention, the weight inspection apparatus according to the sixth aspect further includes an updating means for updating the reference weight stored in the storage means. According to an eighth aspect of the present invention, in the weight inspection apparatus according to the seventh aspect, the updating unit is the weight of the molded product when the determining unit determines that the molded product is a good product, and It is characterized in that the measured weight is updated to the average value of the measured weight for a predetermined number of times up to a predetermined number of times.

According to a ninth aspect of the present invention, in the weight inspection apparatus according to the eighth aspect, the updating means updates the reference weight every time the determining means determines that the molded product is a good product. It is what According to a tenth aspect of the present invention, in the weight inspection apparatus according to any one of the first to fifth aspects, further, a storage unit having a plurality of predetermined storage areas and the determination unit determine that the molded product is a good product. And a means for writing the weight of the molded product in the storage area of the storage means, and an operation for obtaining the average value of the weights of the molded products stored in each storage area of the storage means and outputting it as the reference weight. Means and are included.

According to an eleventh aspect of the present invention, in the weight inspection apparatus according to the tenth aspect, when the weight of the molded product is written in all of the plurality of storage areas, the writing means is the earliest. It is characterized in that the weight of the written storage area is rewritten to the weight of a molded product which is newly determined to be a non-defective product. The invention according to claim 12 is the weight inspection apparatus according to claim 10 or 11, wherein the injection molding is
Molding is performed by equipment including a mold for molding a molded product and an injection molding machine for filling a mold with a molding material, and the weight inspection device is provided below the mold and is dropped from the mold. It is characterized in that it includes a conveying means for conveying an item to the weight measuring means.

According to a thirteenth aspect of the present invention, in the weight inspection apparatus according to any of the fifth to twelfth aspects, an absolute reference value is further stored in the storage means, and the determination means is the above-mentioned. When the weight measured by the weight measuring means is equal to or more than a predetermined difference from the absolute reference value, it is determined that there is a possibility of defective product regardless of the output of the comparing means.

According to a fourteenth aspect of the present invention, there is provided a method for discriminating whether a molded product molded by injection molding is a good product or a defective product, wherein the weight of the molded product molded by one injection molding operation is measured. , The measured weight is compared with a predetermined reference weight, and if the measured weight is within a predetermined tolerance with respect to the reference weight, the molded product is determined as a good product, and the measured weight is compared with the reference weight. If it exceeds a predetermined standard difference, it is characterized that the molded product may be defective.
This is a method for discriminating molded articles.

According to a fifteenth aspect of the present invention, in the discrimination method according to the fourteenth aspect, the method further comprises a step of sorting the molded products into good products and defective products based on the determination result. Is the way. The invention according to claim 16 is the discrimination method according to claim 14 or 15,
The predetermined reference weight is a method for discriminating the molded product, which is characterized in that the reference weight is sequentially updated in accordance with the measurement.

[0022]

According to the invention described in claim 1, the weight of the molded article molded by one injection molding operation is measured, and the weight is compared with a predetermined reference weight. If the difference is within a predetermined allowable value, the molded product is determined to be a good product, and if it exceeds the allowable value, the molded product is determined to be a defective product. Therefore, the quality of the injection-molded molded product can be efficiently judged by the mechanical device based on its weight.

According to the second aspect of the invention, when a plurality of molded products of the same shape are simultaneously molded by injection molding,
The plurality of molded products are collectively judged at one time.
Some of the dies used for injection molding are, for example, four pieces, six pieces, eight pieces, and the like, so that a plurality of molded articles having the same shape can be simultaneously formed. When such a mold is used, when the weight of each molded product is individually measured, there is variation depending on the mold even though the molded products have the same shape. However, in the method of measuring the total weight of a plurality of molded products that are molded at the same time, variations in individual products can be absorbed, and the quality of the molded products can be quickly determined.

As a result, as in the invention described in claim 3,
If the difference between the measured total weight of the molded product and the reference weight exceeds the allowable value, at least one of the plurality of products whose weight has been measured contains a defective product. It can be determined that there is a possibility. In the invention according to claim 4, the weight inspection is performed by the weight inspection device in conjunction with the injection molding operation. That is, the weight of the molded product is measured immediately after molding. Therefore, even if the molded product is a resin molded product and has a hygroscopic property, the weight is measured immediately after the molding, so that it is possible to accurately determine the quality.

In the invention according to claim 5, the molded products are sorted as a result of the quality judgment. Therefore, the inspector may determine that there is a possibility of defective product, and visually confirms whether or not the molded product is defective with respect to the relatively small number of distributed molded products. According to the sixth aspect of the invention, the storage means for storing the reference weight is included. Further, in the invention according to claim 7, the reference weight stored in the storage means is updated by the updating means. The updating means uses a plurality of weights of the molded product when the molded product is determined to be a good product in the past as in the invention of claim 8, and updates so that the reference weight becomes the average value. In the calculation of the average value, the average value of the weights of the non-defective products for the predetermined number of times of the latest weight discrimination result is calculated. For example, the average value of the weights of the molded products which have been determined as good products for the past 50 times is calculated. By doing so, even if the weight of the molded product changes in a wavy manner with the molding operation, the average weight also changes in accordance with the waviness, so that the reference weight adapted to the waviness can be obtained.

According to the invention described in claim 9, since the average weight is updated successively, the latest reference weight can always be obtained. According to the tenth aspect of the present invention, the reference weight is not stored in the storage means, but the weights of the molded products for the past multiple times when the molded product is determined to be a good product are stored in the storage device. . Then, each time the need arises, the average value of the weights of the plurality of molded products stored in the storage means is obtained and used as the reference weight. In this way, it is easy to update the reference weight.

In the invention according to claim 11, the weight of the molded product which is the basis of the reference weight is constantly updated to a new one, so that the reference weight can also be updated to the latest one. . According to the twelfth aspect of the present invention, the molded articles taken out from the mold can be sequentially sent to the weight inspection by the conveying means in conjunction with the lines of the molding mold and the injection molding machine.

According to the thirteenth aspect of the present invention, the absolute reference value is further defined, and when the measured weight of the molded product deviates from the absolute reference value by a predetermined difference or more, it may be a defective product. It is determined that there is a property. Therefore, the possibility of defective products can be selected more strictly. Claim 1
According to the methods described in 4 to 16, it is possible to appropriately determine in a short time whether the molded product molded by injection molding is a non-defective product or a defective product based on its weight.

[0029]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an illustrative view showing the overall configuration of a weight inspection device according to an embodiment of the present invention, and is shown together with an injection molding machine. Referring to FIG. 1, reference numeral 1 is a heating cylinder of an injection molding machine, and a screw 2 is fitted in the heating cylinder 1. An oil motor 3 is connected to the rear end of the screw 2, and the screw 2 is moved by the oil motor 3 to the front F and the rear B. A hopper 4 is provided above the rear part of the heating cylinder 1. The resin material (not shown) put in the hopper 4 is supplied to the heating cylinder 1.

When the screw 2 is rotated and moved backward B, the resin material supplied from the hopper 4 is sent forward by the screw 2 and is filled in the front of the heating cylinder 1 while being melted. At this time, the amount of the backward movement of the screw 2 determines the amount of the molten resin filled in the cylinder 1, which is the amount consumed for one injection. When the screw 2 is slid in the forward direction F, the molten resin filled in the heating cylinder 1 is injected from the injection nozzle 5 at the tip of the heating cylinder 1 and sent into the mold 6.
The molten resin filled in the mold 6 is placed under a predetermined pressure condition for a certain period of time and solidifies. That is, the molten resin in the mold 6 is retained by the screw 2. And mold 6
After the resin inside is solidified, the mold 6 is opened by the opening / closing device 7,
The solidified resin molded product is taken out. After that, the mold 6 is closed again by the opening / closing device 7, and the next molding process is started.

The resin molding includes a series of injection strokes, pressure holding strokes, and opening / closing strokes of the mold 6 as described above. The weight inspection apparatus according to the present embodiment measures the weight of the molded product in association with the series of resin molding processes described above to determine whether the molded product is a good product or a defective product. Determine. Therefore, in this embodiment, a belt conveyor 11 arranged below the mold 6 is provided. The belt conveyor 11 is driven by the motor 12 only when necessary or at all times. When the mold 6 is opened, the molded product solidified in the mold 6 falls below the mold 6. The molded articles that fall are received by the belt conveyor 11 and the weight inspection device 1
Carried to 3. The weight inspection device 13 includes an electronic balance 14, which will be described in detail later, and a windshield 1 for protecting the electronic balance 14 from wind.
5 and a display 16 are included. Weight inspection device 13
Then, based on the weight of the molded product, it is determined whether the molded product is a good product or a defective product. Then, the non-defective product is sent to the non-defective product box 17, and the molded product that may be a defective product is sent to the defective product box 18.

2A and 2B are views showing the positional relationship between the mold 6 and the weight inspection device 13 of the injection molding machine shown in FIG. More specifically, FIG. 2A shows the positional relationship between the mold 6 and the weight inspection device 13 viewed from the direction of the arrow F in FIG. 1, and FIG. 2B shows the mold 6 when viewed from the left side of FIG. 2A.
The positional relationship between the weight inspection device 13 and the weight inspection device 13 is shown. Figure 2A
2 and 2B, in this embodiment, the mold 6 is a so-called four-cavity mold, and four molded products of the same shape are formed by molding once (in the following description, the molded products are The case of the connector housing will be described as an example). When the mold 6 is opened as shown in FIG. 2B, the four housings (not shown) drop downward. Below the mold 6, a belt conveyor 11 is arranged substantially horizontally so as to extend in a direction orthogonal to the opening / closing direction of the mold 6. Therefore, the housing falling from the mold 6 is the belt conveyor 11
Can be received at. Then, when the belt conveyor 11 is driven, the housing is sent to the weight inspection device 13 arranged on the front side of the mold 6.

The weight inspection device 13 is arranged, for example, on the table 19, and vibrations of the floor 20 and the like are detected.
It is supposed not to be transmitted to. In addition, the weight inspection device 1
A non-defective box 17 and a defective box 18 are arranged on both sides of 3, and the housing subjected to the weight inspection is discriminated and sorted into the non-defective box 17 or the defective box 18. FIG.
It is a perspective view showing a configuration of a weight inspection device 13. FIG. 4 is a front view of the weight inspection device.

With reference to FIGS. 3 and 4, the weight inspection device 13 is provided with the electronic balance 14 as described above. The electronic balance 14 is, for example, an electromagnetic balance type electronic balance having a measuring table 20 on which a measured object (housing) is placed,
A high-precision one with a weighing capacity of 410 g and a minimum display of 0.001 g is used. If the housing to be inspected is dropped on the measuring table 20, the high-precision electronic balance 14 may cause a failure. Therefore, in this embodiment, the saucer 2 is placed on the measuring table 20.
1 is provided. The saucer 21 is a pair of arms 22, 2
Supported by 3. When the housing to be measured is placed on the pan 21, the arms 22 and 23 are located above, and the pan 21 is floated on the measuring table 20.
In this state, the housing to be measured is dropped on the pan 21. Then, at the time of measurement, the arms 22 and 23 are gently lowered, and the tray 21 on which the housing is placed is placed on the measuring table 20. The saucer 21 is provided with legs 21a at the four corners of its lower surface, and the four legs are in contact with the back surface of the measuring table 20. Therefore, at this time, a gap is formed between the lower surface of the saucer 21 and the surface of the measurement table 20, and the arms 22 and 23 are located in the gap and apart from the saucer 21.

A storage box 2 is provided at the rear of the electronic balance 14.
4 are erected. The lower portion of the storage box 24 is connected to the back surface of the electronic balance 14, and the storage box 24 extends upward along the back surface of the electronic balance 14 and covers the back surface side of the electronic balance 14. Inside the storage box 24, the arms 2 and 23 are connected to the rear part of the arm 2 and
A drive mechanism (see FIG. 5) for moving the Nos. 2 and 23 up and down is provided. The drive mechanism will be described later.

The electronic balance 14 and the saucer 21 further include
The peripheries (front surface, left and right side surfaces, upper surface) are covered with a windshield 15. The windshield 15 is connected to the storage box 24, and the storage box 24 and the windshield 15 cover the entire circumference of the electronic balance 14 and the pan 21.
Since the electronic balance 14 has high accuracy, the measurement table 20 vibrates slightly when a wind, especially a side wind is received, and the measured value is difficult to stabilize. Therefore, in this embodiment, the electronic balance 1 is provided by the windshield 15.
4 and its attachments. Windshield 15
Is a top plate 25, a left side plate 26, a right side plate 27 and a front plate 28.
Each of these plates is made of, for example, a transparent or translucent acrylic plate so that the inside can be confirmed. Of course, it may be composed of an opaque member. The top plate 15 and the left and right side plates 26, 27 are connected to each other and to the storage box 24. on the other hand,
The front plate 28 can be opened and closed. Specifically, the front plate 2
The right side of 8 is connected to the front side of the right side plate 27 via a pair of hinges 29. And near the center of the left side of the front plate 28,
A small handle 30 is provided so as to be gripped when the front plate 28 is opened.

An opening 31 is formed in the central portion of the top plate 25, and a receiving gutter 32 opened upward from the top plate 25 is connected to the opening 31. The conveyor belt 11 is arranged to carry the housing H into the receiving gutter 32. Below the opening 31 of the top plate 25, there is provided a guide gutter 33 extending in the windshield 15 and having a rectangular shape, for example. The guide gutter 33 is for guiding the housing H put in the receiving gutter 32 onto the tray 21. That is, the guide gutter 33 is received by the receiving gutter 32 and the opening 3
The housing H is guided onto the tray 21 so that the housing H falling from 1 does not spill from the tray 21.

The periphery of the receiving tray 21 is bent upward in order to securely receive the housing H dropped through the guide trough 33. That is, the saucer 21 has a boat-shaped flat bottom surface. When the pan 21 on which the housing is placed is placed on the measuring table 20, the weight of the pan 21 including the housing is measured. And from the measured value the saucer 21
The housing weight from which the weight is subtracted is displayed on the display 16 as a measurement result. The display 16 includes a stability degree display bar 161 and four weight display numerical segments 162.
, A pass lamp 163 and a fail lamp 164 are included. The stability degree display bar 161 is for notifying that the measuring table 20 is stable, and the weight is displayed by the numerical segment 162 after the measuring table 20 is stabilized. This weight is the weight of the housing excluding the weight of the tray 21 as described above. Of course, the weight including the weight of the tray 21 may be used. This can be easily changed by calculation. The pass lamp 163 lights up when the weight of the housing is within a predetermined range with respect to a reference weight described later, and the fail lamp 164 lights up at other times.

Windows 34 and 35 are formed in the lower portions of the left side plate 26 and the right side plate 27, respectively.
Slides 36 and 37 are attached to the slides. Slide 3
Reference numerals 6 and 37 extend downward from the inner space of the windshield 15 through the windows 34 and 35 to the housing H that slides out of the tray 21 as described below.
(See FIG. 2). Windows 34,3
Shutters 38 and 39 are engaged with 5, respectively. The shutters 38 and 39 are attached to the tips of the rods 42 and 43 of the left and right shutter cylinders 40 and 41, respectively. The left and right shutter cylinders 40 and 41 are fixed to the top plate 25 by mounting plates 44 and 45. When the left and right shutter cylinders 40 and 41 are turned on, the rod 4
2, 43 contract, and the shutters 38, 39 attached to the tips of the rods 42, 43 slide upward. This opens the windows 34, 35. On the contrary, when the left and right shutter cylinders 40 and 41 are turned off, the rods 42 and 43 extend and the shutters 38 and 39 descend to close the windows 34 and 35. In this way, the windows 34, 35 can be opened only when necessary, so that cross wind can be prevented from entering the windshield 15 through the windows 34, 35. Left and right shutter cylinder 40,
41 on / off timing, in other words window 34,
The opening / closing timing of 35 will be described later.

FIG. 5 is a perspective view showing a drive mechanism for the arms 22 and 23. Referring to FIG. 5, the rear ends of the arms 22 and 23 have vertical link plates 46 and 4 extending vertically, respectively.
It is fixed to the lower end of 7. Vertical link plates 46, 47
Horizontal link plates 48 and 49 are connected to the upper end of the.
Then, the horizontal link plates 48, 49 have left and right tray cylinders 5
The tips of the rods 52 and 53 of 0 and 51 are connected. The left and right dish cylinders 50, 51 are arranged such that rods 52, 53 extend and contract in the vertical direction. Also rod 5
Return springs 54 and 55 are provided on the outer surfaces of the reference numerals 2 and 53, respectively. The left and right tray cylinders 50 and 51 are storage boxes 24
(Refer to FIG. 3) It is fixed to the inner frame or the like. Therefore, when the left dish cylinder 50 is turned on, the rod 52 contracts, and as a result, the arm 22 descends. Conversely, when the left dish cylinder 50 is turned off, the rod 52 is operated by the action of the return spring 54.
And the arm 22 rises. Similarly, when the right dish cylinder 51 is turned on, the rod 53 contracts and the arm 23 descends. When the right dish cylinder 51 is turned off, the rod 53
And the arm 23 rises.

When the left and right tray cylinders 50 and 51 are turned on at the same time, the arms 22 and 23 can be lowered at the same time, and the tray 21 can be lowered. On the other hand, when only one of the left dish cylinder 50 and the right dish cylinder 51 is turned on, one of the arms 22 and 23 is in the lower position and the other is in the upper position, so that the tray 21 can be tilted.

FIGS. 6A to 6D show the arms 22 and 23.
FIG. 3 is an illustrative view showing a change in the state of the tray, the state of the tray 21, and the state of the housing H placed on the tray 21. As shown in FIG. 6A, when the housing H is placed on the tray 21, the arms 22 and 23 are both raised and the tray 21 is floated from the measuring table 20. Therefore saucer 2
Even if the housing H is dropped onto the measurement table 1, no impact is applied to the measuring table 20.

Next, at the time of weighing, as shown in FIG. 6B, the arms 22 and 23 are lowered together so that the legs 21a of the tray 21 are brought into contact with the measuring table 21. Next, the arms 22 and 23 are further lowered so that the arms 22 and 23 are located between the pan 21 and the measuring table 20 so that they are not in contact with both. Weight measurement is performed in this state. As a result of the weight measurement, when the measured value is within a certain range with respect to a predetermined reference value, the housing H is determined to be non-defective. When it is judged as a non-defective product, as shown in FIG. 6C, for example, only the arm 23 is lifted. With this, saucer 2
1 tilts diagonally. Therefore, the housing H placed on the pan 21 slides on the pan 21 to the left and falls from the pan 21. The falling housing H slides on the slide 35 (see FIGS. 3 and 4) and drops into the non-defective box 17 (FIG. 2).

Thereafter, the arm 22 is lifted (FIG. 6 (d)) after waiting for the time required for the four housings to completely slide on the saucer 21, and the saucer 21 receives the first housing. Return to the position. When it is determined that the housing H is a defective product, only the arm 2 is lifted from the state of FIG. 6B and the tray 21 is tilted to the right. The housing then slides down into the reject box 18 (see FIG. 2).

FIG. 7 is a block diagram showing a configuration of mainly electrical parts for controlling the drive of the weight inspection device 13 according to this embodiment. The weight inspection device 13 is provided with a control unit 6 including, for example, a microcomputer. The control unit 60 is supplied with a take-out signal from a molding machine sensor 61 provided in the injection molding mechanism. The molding machine sensor 61 is a sensor that outputs a take-out signal when the mold 6 is opened, for example. Alternatively, it may be a sensor that outputs a take-out signal when the injection process by the injection molding machine is completed. That is, the molding machine sensor 61 may be any sensor that outputs a take-out signal in response to the completion of the injection molding process.

The control unit 60 controls the conveyor drive circuit 67 and the cylinder drive circuit 68 based on the signal from the sensor 61. Specifically, in response to the take-out signal from the molding machine sensor 61, the control unit 60 gives a signal to the conveyor drive circuit 67 and causes the conveyor drive circuit 67 to rotate the motor 12. The rotation of the motor 12 drives the belt conveyor 11. Control unit 60
Also gives a signal to the cylinder drive circuit 68 to move the arm 22 up and down, the plate left cylinder 50, the arm 23 up and down, the plate right cylinder 51, and the shutter 38 up and down. The right shutter cylinder 41 for vertically moving the cylinder 40 and the shutter 39 is turned on / off.

The control unit 60 also calculates the weight of the housing H placed on the measuring table 20 based on the weighing signal given from the measuring table 20, and compares it with the reference weight stored in the memory 81. To do. As a result, it is determined whether the housing H is a good product or a defective product. The calculated weight and the determination result are given to the display 16 and displayed. If the calculated weight of the housing H is, for example, continuously classified into defective products five times or more, the pin breakage of the mold may be considered. Therefore, a signal is sent to the abnormality notification device 69. It is preferable that the inspection request is made to the operator.

FIG. 8 is a timing chart for explaining the operation of the block diagram of FIG. Next, with reference mainly to FIGS. 3 and 7, the operation of the weight measuring device 13 will be described according to the timing chart shown in FIG. First, a take-out signal from the molding machine sensor 61 is given. This signal is a pulse signal as shown in FIG. 8, and for example, when the mold 6 is opened by the opening / closing device 7 (see FIG. 2).
The pulse signal is output to (see B). In response to this take-out signal, the control unit 60 gives an ON signal to the conveyor drive circuit 67, and accordingly, the conveyor drive circuit 67 causes the motor 12 to operate.
Is rotated and the belt conveyor 11 is driven. The driving of the belt conveyor 11 is stopped after a preset time has passed. In other words, in this embodiment, the belt conveyor 11 is driven only when necessary, and the housing H dropped on the belt conveyor 11 is removed from the weight inspection device 1.
It is designed to be transported to No. 3.

However, if the period of one cycle of resin molding is short, it may not be desirable to turn the belt conveyor 11 on and off frequently, so the belt conveyor 1
1 may be always driven. Control unit 60
Starts the time counting operation in response to the take-out signal given from the molding machine sensor 61, and gives a signal to the cylinder drive circuit 68 when a predetermined time has elapsed from the rise of the take-out signal to cause the left dish cylinder 50 and the right dish cylinder 50 The dish cylinder 51 is turned on. During this predetermined time, the mold 6 is opened and the housing H drops onto the belt conveyor 11, and the dropped housing H is conveyed to the weight inspection device 13 by the belt conveyor 11 and dropped onto the pan 21. It is considered necessary and sufficient time.

In this embodiment, the mold 6 is used as described above.
Is a so-called four-cavity mold, so when the mold 6 is opened, four housings are moved to the belt conveyor 11 at a time.
Fall to the top. Then, the four housings H are conveyed to the weight inspection device 13 and dropped onto the tray 21. When the left dish cylinder 50 and the right dish cylinder 51 are turned on at the same time, the tray 21 on which the four housings H are placed moves down from the upper position to the lower position. In the control unit 60, the left dish cylinder 5
0, the weighing signal from the measuring table 20 is taken in after a slight time delay from the rising signal of the right dish cylinder 51. Saucer 21
The measurement table 20 vibrates slightly immediately after being mounted on the measurement table 20. Therefore, the weighing signal is not stable at first, but soon the measuring table 20 is stationary, and the weighing signal is also stable. The control unit 60 calculates the weights of the four housings based on the stable weighing signal. The weight of the four housings is obtained by subtracting the weight of the pan 21 from the weight represented by the weighing signal. The weight of the tray 21 itself is measured and stored in the memory 81 at the time of initial setting, for example. The stability of the weighing signal is displayed on the stability display bar 161 of the display unit 16. When the bar 161 indicates stability, the numerical segment 162 displays the total weight of the four housings H.

The controller 60 compares the calculated housing weight with a reference weight preset in the memory 81. Then, as a result of the comparison, if the housing weight calculated with respect to the reference weight is within a predetermined tolerance, it is determined that all four housings are acceptable products. On the other hand, if it is not within the tolerance, it is determined that at least one of the four housings has a defective product. The result of this determination is given to the display 16, and the pass lamp 163 or the fail lamp 164 is turned on. How to make this determination and how to determine the reference weight will be described later.

If the result of the determination is, for example, that the result is acceptable, only the right dish cylinder 51 is turned off and the left dish cylinder 5 is turned off.
0 remains on. That is, as described in FIG. 6C, the tray 21 is tilted to the left. At the same time, the left shutter cylinder 40 and the right shutter cylinder 41 are turned on, the shutters 36 and 37 on both sides are pulled up, and the windows 34 and 35 on both sides are opened. Therefore, the four housings H which are determined to be non-defective on the pan 21 are mounted on the slide 36 and the sliding window 34.
And is dropped into the non-defective box 17.

When the control unit 60 determines that the product is defective, the left tray cylinder 5 is adjusted so that the tray 21 is tilted to the right.
0 is turned off, and the right dish cylinder 51 is kept on. Then, after the time required for the four housings H on the pan 21 to completely slide down, the left pan cylinder 50 is turned off and the pan 21 is returned to the upper position. Then, after a short delay, the left shutter cylinder 4
0, the right shutter cylinder 41 is turned off, and the shutter 3
7, 38 are lowered and windows 34, 35 are closed.

In this embodiment, the left shutter cylinder 4
Since the 0 and right shutter cylinders 41 are controlled to be turned on / off at the same time, the windows 34 and 35 are opened at the same time. However, instead of such control, for example, the pan 21 is tilted to the left and the window 3
When taking out the housing H from 4, only the left shutter cylinder 40 is turned on so that only the window 34 is opened,
The right shutter cylinder 41 may remain off.

FIG. 9 is an illustrative view showing one example of a storage area provided in the memory 81 shown in FIG. Memory 8
Reference numeral 1 has a storage area for storing the weight of the housing which has been determined as a non-defective product for the past N times (for example, 50 days). In each storage area, the good product weight measured in the past is stored. When it is determined that the newly measured housing is non-defective, the weight is stored in the memory 81. In this case, the weight written first, ie N
Instead of the weight of the non-defective product before (50 times before), the weight of the housing that has been measured most recently and determined as the non-defective product is written.
Alternatively, as shown in FIG. 9, the weight of the non-defective product N times before (50 times before) is expelled from the storage area of the memory 81, the stored contents are sequentially shifted one by one, and the weight of the previous non-defective product is stored. The weight of the housing measured this time may be written in the existing area.

The allowable value D, the absolute reference minimum weight W _L , and the absolute reference maximum weight W _U are also stored in the memory 81 in advance. Also, a counter area for counting the number of consecutive defective products is provided. The contents of these will be described later. FIG. 10 is a flow chart showing a method of control regarding the determination of the quality of the housing and the update of the reference weight, which is performed by the control unit 60 shown in FIG. 7. Explaining with reference to FIG. 10, the control unit 60 measures the weight Wm of the housing based on the weighing signal given from the measuring stand 20 (step S1). The measured weight Wm is displayed by the numerical segment 162 of the display 16 (step S2).

Next, the control unit 60 calculates the reference weight Wa (step S3). As shown in FIG. 9, when the weight of the non-defective product for the past N times is stored in the memory 81, the reference weight Wa is added with the weights of the non-defective products for the N times and divided by N, and the average thereof is calculated. This is done by asking for a value. Next, the control unit 60 controls the reference weight Wa.
Then, it is judged whether or not the value of the difference obtained by subtracting the measured weight Wm of this time is less than or equal to the predetermined allowable value D (step S4). When the difference value obtained by subtracting the measured weight Wm of this time from the reference weight Wa is D or less, the measured weight Wm is more than the predetermined absolute weight lower limit value W _L and the absolute weight upper limit value W _U. It is determined whether or not the following (step S5). If YES in step S5, it is determined that the molded housing is non-defective, and the non-defective lamp 163 of the display 16 is turned on (step S6).

After displaying the non-defective product, the counter for counting the number of consecutive defective product occurrences provided in the memory 31 is cleared (step S7). Then, in the cylinder drive circuit 68,
A signal when it is determined as a non-defective product is given, and the left and right dish cylinders 50 and 51 and the left and right shutter cylinders 40 and 4 are provided.
1 is drive-controlled (step S8). After that, the rewriting process of the weight of the non-defective product in the memory 81 is performed (step S9). As described above, this weight rewriting process is a process in which the weight of the non-defective product measured this time is written in place of the weight of the non-defective product written first.

On the other hand, when NO is determined in step S4 or when NO is determined in step S5,
The housing may be a defective product, and it is determined that the housing is defective, and the defective lamp 164 of the display 16 is turned on (step S10). Then, the counter for counting the number of consecutive defective products in the memory 81 is incremented by 1 (step S
11). Next, the cylinder drive circuit 68 is supplied with a drive signal when it is determined that the product is defective. As a result, as described above, the housing determined to be a defective product is sorted into the defective product box 18.

Next, it is judged whether or not the count value of the continuous defective product occurrence count counter is, for example, "5" (step S13). If the count value of the counter is "5", defective products are detected five times in succession, so it can be inferred that an abnormality such as a pin break has occurred. Therefore, in such a case, the abnormality notification circuit 69 is activated to notify the abnormality (step S14).

If the count value of the counter is less than "5" in step S13, the process directly returns. In the control shown in FIG. 10, the weight is written in step S9, and the weight which is the basis for calculating the reference weight Wa is rewritten. The reason for this will be described in more detail with reference to FIG.

FIG. 11 shows an example of actual measurement data measured by the weight inspection apparatus according to the embodiment of the present invention shown in FIG. In FIG. 11, the horizontal axis represents the number of injection moldings, and the vertical axis represents the weight of a so-called 4-piece molded product (total weight of 4 pieces). As is clear from FIG. 1, the weight of the molded product (total weight of four housings H)
Is slightly different for each molding operation, but when the weight is extremely small (A in FIG. 11) or extremely large (B in FIG. 11), it is determined as a defective product. Is a typical example of.

On the other hand, looking at the actual measurement data shown in FIG. 11 along the horizontal axis, it can be seen that the measured weight Wm changes in a large undulation as the number of injection moldings changes. For example, in the injection molding operation in the range R1, the housing weight when it is determined to be a good product is about 33.14 grams, whereas in the injection molding operation in the range R2, it is determined to be a good product. The average weight is 33.175 grams. In this way, the weight of the molded product is
It changes like waviness over time. Therefore, for example, in the latter half of the range of R2 shown in FIG. 11, if the reference weight Wa is the same as the reference weight Wa used in R1, the measured weight Wm is significantly different from the reference weight Wa. Therefore, all measured products may be determined to be defective. Therefore, it is necessary to sequentially update the reference weight Wa as the number of measurements increases.

Therefore, in the control shown in FIG. 10, the weight is rewritten in step S9, and the reference weight Wa (basic data thereof) is sequentially updated. Instead of rewriting the weight in step S9 of FIG. 10, in step S9, the calculation shown in the following formula is performed,
The updated reference weight _new Wa may be calculated.

[0065]

[Equation 1]

By doing so, the memory area for storing the weight of non-defective products for N times in the memory 81 can be omitted. Furthermore, in the control shown in FIG.
In 5, the measured weight Wm is compared with the absolute weights W _L and W _U. Therefore, since the measured weight Wm is compared with the average weight Wa and the absolute weight in two steps, it is possible to more accurately determine whether the product is a good product or a defective product.

The comparison with the absolute weight can be omitted in some cases. In the above examples,
When it is determined that the molded product is defective, the molded product is not necessarily declared as defective, and the molded product may be defective. The reason is that there is a weight error and a measurement error of the molded product, and it is considered that it may be difficult to declare the defective product based only on the measured weight. However, when a molded product is discriminated by this weight inspection device, a defective product is not mixed in the molded product discriminated as a good product. In other words, the reference value for the quality determination is set so that the defective product is not mixed in the molded product determined to be a good product. By doing so, the non-defective product can be automatically determined by the mechanical device. Therefore, it is possible to omit the labor required for the inspection, which has been conventionally performed by many inspectors.

Further, a good product may be mixed in the molded products determined to be defective products. As described above, the number of molded products determined to be defective is extremely small. Therefore, it is extremely easy for the inspector to visually inspect the molded product determined as the defective product and take out the good product from the inspection. In particular, in the present invention, when a molded product is molded by a so-called multi-molding die, it is not judged whether each molded product is good or bad. Therefore, all the molded products that are judged to be non-defective products are non-defective products.
Good products may be mixed in the molded products determined as defective products.

In the above embodiment, the absolute weight is stored in the memory 81.
However, the absolute weight may be set by, for example, a dip switch and may be sequentially changed by the operator. In such a case, the operator can appropriately change the absolute weight while observing the molding condition of the molded product. Further, in the above-described embodiment, the absolute weight is defined as the absolute minimum weight W _L and the absolute maximum maximum weight W _U. However, one absolute standard weight is defined and the absolute standard weight is If the measured weight is within a predetermined range, it may be determined as a non-defective product.

In the above embodiments, the case of inspecting the connector housing of the wire harness in which four molds are simultaneously molded by the so-called four-molding die 6 has been described. However, the present invention can be applied to the quality judgment of various resin molded products molded by injection molding other than the connector housing, and the design may be changed according to the type of the resin molded product to be measured.

Although the mold 6 is a so-called four-cavity mold, it can be applied to a six-cavity mold or an eight-cavity mold. In addition, the present invention can be variously modified within the scope of claims.

[0072]

According to the present invention, by using a mechanical device,
It is possible to automatically determine whether the injection-molded product is a good product or a defective product. Therefore, it is possible to save the labor of the visual inspection by a large number of inspectors, which has been conventionally performed. When it is determined that the molded product may be defective according to the present invention, the inspector may visually check only the product. Since the number of molded products that are determined to be defective is extremely small, the number of objects to be visually inspected by an inspector is small, and inspection can be performed with less labor.

Further, according to the present invention, the reference weight for determining whether there is a possibility of non-defective product or defective product is sequentially updated according to the number of times of injection molding overlap.
While injection molding is repeated for a long period of time, the weight of a molded product may change like a wavy shape due to subtle qualitative changes in the molding material, changes in the ambient temperature of the molding equipment, etc. . Therefore, by updating the reference value, it is possible to provide a device which can follow the undulating weight change of the molded product and can accurately determine the quality of the molded product.

[Brief description of drawings]

FIG. 1 is an illustrative view showing a configuration of a weight inspection device according to an embodiment of the present invention together with an injection molding machine.

FIG. 2 is a diagram showing a positional relationship between a mold and a weight inspection device.

FIG. 3 is a perspective view showing a configuration of a weight inspection device according to an embodiment of the present invention.

FIG. 4 is a front view showing the configuration of a weight inspection device according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a drive mechanism of an arm for moving a saucer.

FIG. 6 is an illustrative view showing a change in a state of a tray moved by an arm.

FIG. 7 is a block diagram showing an electrical configuration of a weight inspection device according to an embodiment of the present invention.

8 is a timing chart for explaining the operation of the block diagram shown in FIG. 7.

9 is an illustrative view showing stored contents of a memory 81. FIG.

FIG. 10 is a flowchart for explaining a control operation regarding a reference weight update process in the control unit.

FIG. 11 is a diagram showing an example of actual measurement data of the weight of a molded product according to this example.

FIG. 12 is a perspective view showing an example of a defective housing.

[Explanation of symbols]

 6 Mold 11 Belt Conveyor 12 Motor 13 Weight Inspection Device 14 Electronic Balance 15 Windshield 16 Display 20 Measuring Stand 21 Sauce 22, 23 Arm 34, 34 Window 38, 39 Shutter 40, 41 Cylinder 50, 51 Cylinder

Claims (16)

[Claims] 1. A device for discriminating a molded product molded by injection molding based on the weight of the molded product, wherein a weight measuring means for measuring the weight of the molded product molded by one injection molding operation, If the weight of the molded product measured by the weight measuring means is compared with a predetermined reference weight and the difference is outputted as a comparing means, and the value of the difference outputted from the comparing means is within a predetermined allowable value, then A weight inspection apparatus, comprising: a determination unit that determines a molded product as a non-defective product, and determines that the molded product may be a defective product if the difference value exceeds a predetermined allowable value. 2. The weight inspection apparatus according to claim 1, wherein a plurality of molded products having the same shape are simultaneously molded by the one injection molding operation, and the weight measuring means is configured to perform the plurality of simultaneously molded products. It is characterized by measuring the total weight of the molded product,
Weight inspection device. 3. The weight inspection apparatus according to claim 2, wherein the discriminating means determines that a plurality of weight-measured molded articles are produced if the difference value output from the comparing means is within a predetermined allowable value. All of them are judged to be non-defective products, and if the difference value exceeds a predetermined allowable value, it is judged that defective products may be included in the multiple weight-measured molded products. This is a weight inspection device. 4. The weight inspection apparatus according to claim 1, wherein the injection molding operation is continuously and sequentially repeated, and the weight inspection apparatus operates in conjunction with the injection molding operation. It is characterized in that the weight of a molded product molded by one injection molding operation is measured until the molded product is molded by the next injection molding operation, and the above-mentioned determination is performed based on the measured weight. A weight inspection device. 5. The weight inspection apparatus according to any one of claims 1 to 4, further comprising a sorting means for distinguishing a molded product according to a determination result of the determining means. Inspection device. 6. The weight inspection apparatus according to claim 1, further comprising a storage unit, wherein the reference weight is stored in the storage unit. . 7. The weight inspection apparatus according to claim 6, further comprising update means for updating the reference weight stored in the storage means. 8. The weight inspection apparatus according to claim 7, wherein the updating means is the weight of the molded product when the determining means determines the molded product as a non-defective product, and the latest measured weight. To a predetermined number of times, the weight inspection device is updated to an average value of measured weights for a predetermined number of times. 9. The weight inspection apparatus according to claim 8, wherein the updating unit updates the reference weight every time the determining unit determines that the molded product is a good product. Weight inspection device. 10. The weight inspection apparatus according to claim 1, further comprising a storage unit having a plurality of predetermined storage areas, and the molded product determined to be a good product by the determination unit. A means for writing the weight of the molded product in the storage area of the storage means; an arithmetic means for obtaining an average value of the weights of the molded products stored in each storage area of the storage means and outputting it as a reference weight; A weight inspection device, comprising: 11. The weight inspection apparatus according to claim 10, wherein the writing unit writes the weight of the molded product to all of the plurality of storage areas, and the storage area is written first. The weight inspection device is characterized in that the weight of the item is rewritten with the weight of the molded item which is newly determined as a non-defective item. 12. The weight inspection apparatus according to claim 10, wherein the injection molding is performed by equipment including a mold for molding a molded product and an injection molding machine for filling the mold with a molding material, The weight inspection apparatus is characterized in that the weight inspection apparatus is provided below the mold and includes a conveying means for carrying a molded product dropped from the mold to the weight measuring means. 13. The weight inspection apparatus according to claim 5, wherein the storage means further stores an absolute reference value, and the determination means measures the weight measurement means. The weight inspection device is characterized in that when the weight is equal to or more than a predetermined difference from the absolute reference value, there is a possibility of defective product regardless of the output of the comparison means. 14. A method for determining whether a molded product molded by injection molding is a good product or a defective product, wherein the weight of the molded product molded by one injection molding operation is measured, and the measured weight is previously calculated. If the measured weight is compared with the specified reference weight and the measured weight is within the specified tolerance, the molded product is judged to be good and the measured weight exceeds the specified reference difference with respect to the reference weight. If so, it is determined that the molded product may be a defective product. 15. The method for determining a molded article according to claim 14, further comprising a step of sorting the molded article into a good product and a defective product based on the determination result. 16. A method for discriminating a molded article according to claim 14 or 15, wherein the predetermined reference weight is sequentially updated along with the measurement.