JP7406821B2 - thermoforming machine - Google Patents

Description

The present invention relates to a technology for using a thermoforming machine that can produce highly accurate molded products using resin sheets with printed patterns.

Sheet molded products are widely used, for example, as food packaging containers and food trays. Such sheet molded products are manufactured using a thermoforming machine and a sheet trimming device, and a method of molding a resin molded sheet using a thermoforming machine is known.

Patent Document 1 discloses a technology related to a molding device and a molding method. A mark provided on the sheet S1 carried into the punching means is detected using a mark detection means. Specifically, a digital camera with a large array of image sensors is used to capture an image, the position of the mark is detected based on the captured image sensor, and if the position of the mark is determined to be outside the standard, the sheet product is punched out. has been suspended.

Patent Document 2 discloses a technique related to a punching device and a punching method. A conveyance means that conveys a continuous resin sheet on which a pattern is printed at approximately constant intervals, which is supplied from a printing sheet supply device, while stopping its operation at a molding timing, and an imaging means that sequentially images the pattern at a molding timing. It is equipped with The amount of printing misalignment of the pattern to be molded imaged by the imaging means is acquired, and the positioning of the upper and lower molds is corrected from the reference position corresponding to the reference pattern to the molding position based on the obtained amount of printing misalignment. It is done by means.

Japanese Patent Application Publication No. 2005-81605 Patent No. 5479763

However, with the techniques described in Patent Documents 1 and 2, it is difficult to precisely adjust the position of a resin sheet on which a pattern is printed. Patent Document 1 does not mention a method for correcting positional deviation, and Patent Document 2 adjusts the position of the mold assuming that the sheet is a continuous sheet. However, even when highly accurate positioning is performed, cases have been confirmed in which positional deviation occurs when heating and molding are performed.

Possible causes of this include, in addition to printing misalignment, changes in machine conditions, operational errors, and temperature conditions of the mold during molding. Since the technique described in Patent Document 1 can only deal with cases where printing misalignment occurs, it may be difficult to obtain a highly accurate molded product as a result.

Therefore, an object of the present invention is to provide a thermoforming machine equipped with a method for precisely positioning a resin sheet on which a pattern is printed.

In order to achieve the above object, a thermoforming machine according to one aspect of the present invention has the following characteristics.

(1) In a molding machine that shapes a pattern-printed resin sheet into a mold or adheres the resin sheet to a base material,
a frame body that positions, holds and conveys the resin sheet;
an imaging means for imaging the resin sheet;
position adjustment means for changing the position of the frame relative to the mold,
Before molding the resin sheet,
imaging the pattern of the resin sheet fixed to the frame with the imaging means to obtain a pre-molding image;
After molding the resin sheet,
imaging the pattern of the molded product obtained by molding the resin sheet using the mold with the imaging means to obtain a post-molding image;
The post-molding image is added to the data used in the position adjustment means for adjusting the position of the frame, and the first information obtained by detecting the amount of deviation from a predetermined reference position using the pre-molding image. using second information obtained by detecting the amount of deviation from the reference position;
It is characterized by

According to the aspect described in (1) above, it is possible to manufacture a molded article by molding a pattern-printed resin sheet with high precision. This involves using an imaging device such as a camera to obtain a pre-molding image to see if there is a pattern at a predetermined position, using this pre-molding image to detect positional deviations, and adjusting the position using a positioning device to form the mold. This is because when performing this, correction is performed using the post-molding image. In other words, by using both images before and after molding, it is possible to obtain a molded product with higher precision.

For example, when checking the positional deviation at the stage before molding as shown in Patent Document 2 from data obtained as a pre-molding image by an imaging means, only some causes such as printing misalignment can be confirmed, and the If the position is adjusted only by using the previous image, the accuracy after molding will be just as good. However, in reality, misalignment with the printing position of the pattern may occur due to thermal effects or the shape characteristics of the mold. For this reason, the amount of deviation in the state of the molded product after molding is determined, including such factors, and is fed back to the position adjustment means as second information using this as a reference. In this way, it contributes to improving the manufacturing accuracy of molded products.

(2) In the thermoforming machine described in (1),
The imaging means includes a first imaging means and a second imaging means,
The first imaging means is provided to take an image of the resin sheet at a heating position where heating is performed,
The second imaging means is provided to take an image of the resin sheet at a molding position where it is molded with the mold,
capturing the pre-molding image with the first imaging means, and capturing the post-molding image with the second imaging means;
is preferred.

According to the aspect described in (2) above, the manufacturing accuracy of the molded product can be improved similarly to (1). This differs in configuration from (1) in that a pre-molding image is captured by the first imaging means at the heating position, and a post-molding image is captured by the second imaging means at the molding position, but the pre-molding image is Since they are the same in that the position of the frame body is adjusted by the position adjustment means using both the image and the post-molding image, the same effect can be obtained.

(3) In the thermoforming machine described in (1),
the imaging means is provided to take an image of the resin sheet at a molding position where it is molded with the mold;
is preferred.

According to the aspect described in (3) above, the resin sheet at the molding position is imaged. In (2), images are taken at different positions, but in (3), the pattern of the resin sheet at the molding position is imaged to obtain both a pre-molding image and a post-molding image. As a result, similar to the effect shown in (1), the manufacturing accuracy of the molded product can be improved.

(4) In the thermoforming machine according to any one of (1) to (4),
using the post-molding screen to check the quality of the molded product formed with the mold;
is preferred.

According to the aspect described in (4) above, by checking the quality of the molded product using the image after molding, it is possible to detect NG of the molded product at an early stage, so a new inspection process is set up afterwards. The manufacturing process can be simplified.

FIG. 1 is a schematic diagram of a thermoforming apparatus according to a first embodiment. It is a schematic plan view of the clamp frame of 1st Embodiment. FIG. 3 is a schematic diagram showing the state of imaging before molding in the first embodiment. FIG. 3 is a schematic diagram showing the state during molding of the first embodiment. FIG. 3 is a schematic diagram showing how an image is taken after molding according to the first embodiment. FIG. 3 is a schematic diagram regarding a misalignment correction screen according to the first embodiment. (a) A schematic diagram illustrating how a pre-molding image is captured in the first embodiment. (b) A schematic diagram showing how the position is adjusted. (c) It is a schematic diagram showing the state of photography of the image after molding. FIG. 2 is a schematic diagram of a thermoforming apparatus according to a second embodiment. FIG. 7 is a schematic diagram showing how the resin sheet is heated in the second embodiment. FIG. 7 is a schematic diagram showing the state during molding of the second embodiment. FIG. 7 is a schematic diagram showing the state of imaging after molding in the second embodiment.

First, an outline of a thermoforming machine 100 according to a first embodiment of the present invention will be explained. FIG. 1 shows a schematic diagram of a thermoforming machine 100. As shown in FIG. 1, the thermoforming machine 100 has a configuration in which a housing 50 includes a hot plate 10, a mold 20, a table 30, and the like. The housing 50 has a structure that is divided into upper and lower parts, and the resin sheet SH held by the clamp frame 40 is placed between them.

Further, a camera 70 is provided on the outside of the housing 50, and is placed at a position to photograph the resin sheet SH held by the clamp frame 40. The thermoforming machine 100 is controlled by a connected control device 80.

The resin sheet SH is a sheet material made of thermoplastic resin, and a pattern described later is printed on its surface. According to the packaging terminology of JIS (Japanese Industrial Standards), a thin plate-like material with a thickness of 250 μm or more is defined as a sheet, and a material with a thickness of less than 250 μm is defined as a film, but in this embodiment, it is defined uniformly without distinction. The resin sheet is called the resin sheet SH.

An upper chamber 51 is provided above the housing 50 across the resin sheet SH, and a lower chamber 52 is provided below. A hot plate 10 is provided in the upper chamber 51 so as to be movable up and down, and a mold 20 is provided in the lower chamber 52 so as to be movable up and down on the table 30 . The elevating mechanism for the hot plate 10 and the table 30 may be a linear motion mechanism such as a cylinder (not shown) or a linear motion mechanism using a motor and a ball screw, but the most suitable one is selected depending on the required specifications.

The hot plate 10 has a function of radiant heating the resin sheet SH in a non-contact manner, but a contact heating type may be used as necessary. The mold 20 is provided at a position opposite to the hot plate 10 with respect to the resin sheet SH, and is a mold for molding the resin sheet SH. Although not particularly shown, the upper chamber 51 is provided with an upper vacuum pressure sensor, an upper vacuum pump, and an upper vacuum bubble, and the pressure inside the upper chamber 51 can be controlled by a signal from the control device 80. . Similarly, the lower chamber 52 is provided with a lower vacuum sensor, a lower vacuum pump, and a lower vacuum bubble, and the pressure within the lower chamber 52 can be controlled by signals from the controller 80 .

The camera 70 is installed outside the housing 50 and is fixed at a position where it can take an image of the resin sheet SH held by the clamp frame 40 when it is in the molding position. Digital data captured by camera 70 is sent to control device 80 . The handling of the imaging data will be described later. Note that the camera 70 used is one that can capture images and obtain high-resolution digital data, such as a CCD camera.

FIG. 2 shows a schematic plan view regarding the clamp frame 40. The resin sheet SH has a structure in which it is held between clamp frames 40, and a pattern Pa is printed on the surface of the resin sheet SH. In this embodiment, for the sake of explanation, the pattern Pa is assumed to be grid-like lines, but the pattern Pa can be applied to any shape as long as the shading is clear and the edges can be clearly distinguished. It is.

While the resin sheet SH is held in the clamp frame 40, the clamp frame 40 can be moved and adjusted from the input position to the molding position, since the clamp frame 40 employs a configuration that combines a linear motion mechanism (not shown). and can be adjusted in the θ direction. For example, if the right and left sides of the clamp frame 40 are equipped with a linear motion mechanism using different servo motors, and are configured to be rotatable around a fulcrum provided on the left or right side, movement in the X direction is possible. and rotational adjustment in the θ direction. It is conceivable that the position adjustment in the Y direction is also possible by using a linear motion mechanism using a servo motor to perform fine adjustment. In short, any configuration is sufficient as long as it is possible to adjust the movement of the clamp frame 40 in the X-axis direction, Y-axis direction, and θ direction.

The thermoforming machine 100 having the above configuration molds the resin sheet SH according to the procedure described below.

FIG. 3 is a schematic diagram showing the state of imaging before molding. FIG. 4 is a schematic diagram showing the state during molding. FIG. 5 is a schematic diagram showing the state of imaging after molding. Note that the control device 80 is omitted in FIGS. 3 to 5 for convenience of explanation. The resin sheet SH is formed in the order shown in FIGS. 1, 3, 4, and 5.

First, the resin sheet SH is held by the clamp frame 40 and moved between the casings 50 as shown in FIG. In this state, as shown in FIG. 3, the camera 70 captures a pre-molding image P1. At this point, the position of the clamp frame 40 is corrected. Details will be described later.

In FIG. 4, the housing 50 is closed, the table 30 is raised, and the mold 20 is pressed against the resin sheet SH, while compressed air is supplied to the upper chamber 51 and air is removed from the lower chamber 52 to create a vacuum state. The molding process is carried out. Thereafter, as shown in FIG. 5, the casing 50 is opened and the molded product S1 is imaged with the camera 70 to obtain a molded image P2.

FIG. 6 shows a schematic diagram regarding the deviation correction screen. In correcting the position of the clamp frame 40, as shown in FIG. 2, data of a pre-molding image P1 in which the appearance of the grid pattern Pa printed on the surface of the resin sheet SH is captured is used. The reference pattern Pa is enlarged as shown in FIG. 6, and the amount of deviation from the first reference line L1 and the second reference line L2 which are perpendicular to each other is calculated. The correction screen is displayed on a display (not shown) provided in the control device 80.

Since the amount of deviation includes deviations in the X-axis and Y-axis directions and rotational components in the θ direction, for example, pattern search image processing is performed to detect the amount of deviation in the X-axis and Y-axis directions, and then a rotational search is performed. A possible method is to detect the amount of deviation in the θ direction.

FIG. 7 is a schematic diagram illustrating the flow of the misalignment check. FIG. 7(a) shows how a pre-molding image is taken. FIG. 7(b) shows how the position is adjusted. FIG. 7(c) shows how an image after molding is taken. Unlike the schematic diagram shown in FIG. 6 for explanation, the schematic diagram shown in FIG. 7 shows how a circular mark Mk is used. A circular mark Mk and a pattern Pa2 are printed on the resin sheet SH. In FIG. 7A, a pre-molding image P1 is obtained by the camera 70 while the resin sheet SH fixed to the clamp frame 40 (not shown) is stopped at the molding position.

Then, as shown in FIG. 7(b), the position of the resin sheet SH is corrected using the data of the pre-molding image P1. In order to simplify the discussion, FIG. 7 shows how the position is corrected in the X-axis direction. Since the center position of the mark Mk is shifted in the "-X" direction with respect to the center line CL of the mold, the position is corrected by correcting the position of the clamp frame 40 in the "+X" direction. Then, the mold 20 is used to mold the resin sheet SH. Then, as shown in FIG. 7(c), after molding, a post-molding image P2 is photographed with a camera 70 to confirm the quality of the molded product S1. In this case, if the deviation is within the allowable range, it is determined to be a good product, and if the deviation is outside the allowable range, it is determined to be an NG product.

Note that FIG. 7(c) shows that the molded product S1 was molded with a deviation in the θ direction. After detecting the amount of positional deviation using the data of the pre-molding image P1, position adjustment data is created by taking into account the information of the post-molding image P2, and if necessary, the position of the clamp frame 40 is adjusted using a drive mechanism etc. Adjust.

Since the thermoforming machine 100 of the first embodiment has the above configuration, it has the following functions and effects.

First, it becomes possible to improve the shape accuracy of the molded product S1. A thermoforming machine 100 that molds a resin sheet SH printed with a pattern Pa using a mold 20 includes a frame body (clamp frame 40) that positions, holds and conveys the resin sheet SH, and a frame body (clamp frame 40) that positions and holds the resin sheet SH and conveys it. The clamp frame 40 is provided with an imaging means (camera 70) that takes an image of the clamp frame 40, and a position adjustment means that changes the position of the clamp frame 40 with respect to the mold 20.

Then, before molding the resin sheet SH, the pattern Pa of the resin sheet SH fixed to the clamp frame 40 is imaged with the camera 70 to obtain a pre-molding image P1, and after molding the resin sheet SH, the mold 20 is The pattern Pa of the molded product S1 obtained by molding the resin sheet SH using the resin sheet SH is imaged by the camera 70 to obtain a molded image P2.

Then, the post-molding image is added to the data used for the position adjustment means for adjusting the position of the clamp frame 40, and the first information obtained by detecting the amount of deviation from a predetermined reference position using the pre-molding image P1. This is because the second information obtained by detecting the amount of deviation from the reference position using P2 is used in consideration.

As shown in the assignment, simply adjusting the position of the clamp frame 40 using the pre-molding image P1 will not correct the misalignment of the resin sheet SH with respect to the clamp frame 40 and the misalignment of the mold 20 with respect to the stop position of the clamp frame 40. It turns out. However, in order to create a state in which the pattern Pa is printed at an appropriate position on the molded product S1, it is necessary to empirically determine the softening state of the resin sheet SH by the hot plate 10, temperature parameters such as the outside temperature, and the mold 20. I knew that it was also affected by the shape characteristics of the molded product itself, so I had no choice but to look at the finished molded product S1 and imagine what kind of deviation had occurred.

However, when adjusting the position of the clamp frame 40, it is possible to further improve the shape accuracy by taking into account not only the pre-molding image P1 but also the information of the post-molding image P2 placed on the mold 20. It becomes possible. Specifically, the countermeasures can be changed simply by understanding whether the pattern Pa of the molded product S1 is misaligned before or after molding. In other words, by being able to isolate the cause, more reliable position adjustment becomes possible.

In addition, by acquiring this post-molding image P2 and checking the state of the molded product S1 to determine whether it is an NG product, it is possible to prevent NG products of the molded product S1 from being sent to the subsequent process. . NG products may be removed manually by an operator, or a discharge function may be provided. Moreover, by being able to detect an NG product in the molded product S1 at an early stage, it becomes possible to eliminate wasteful processes. That is, since the process of determining NG products is not necessary, the effect of omitting the process of inspecting the molded product S1 can be expected.

To simplify a specific example, if it is confirmed that a rotational deviation has occurred in the θ direction by an angle θ1 when comparing the pre-molding image P1 with the first reference line L1 and the second reference line L2, the clamp The frame 40 is corrected by minus θ1 rotation in the θ direction and molding is performed. When comparing the post-molding image P2 with the first reference line L1 and the second reference line L2, if it is found that the molding is deviated by an angle θ2, then when adjusting the position of the clamp frame 40 next time, By correcting the rotation by "θ1+θ2" in the negative direction, a molded product S1 without any deviation can be obtained.

Of course, misalignment may occur in the X-axis direction and the Y-axis direction, but even in this case, by adjusting the position of the clamp frame 40 using the pre-molding image P1 and the post-molding image P, high precision molding can be achieved. It becomes possible to provide the product S1. Since the molded product S1 can be determined to be NG by acquiring the post-molding image P2, there is no need to perform a NG determination regarding molding defects in a later process.

Next, a thermoforming machine 100 according to a second embodiment of the present invention will be described. In the thermoforming machine 100 of the second embodiment, parts having the same configuration as those of the thermoforming machine 100 of the first embodiment are described with the same reference numerals.

FIG. 8 shows a schematic diagram of a thermoforming apparatus according to the second embodiment. FIG. 9 schematically shows how the resin sheet is heated. FIG. 10 schematically shows the state during molding. FIG. 11 is a schematic diagram showing the state of imaging after molding. In the second embodiment, as shown in FIG. 8, the location where the hot plate 110 heats the resin sheet SH is provided as a heating position St1 different from the location where the resin sheet SH is molded. At the heating position St1, a first camera 71 is arranged at a position where it can image the resin sheet SH held by the clamp frame 40.

The clamp frame 40 is moved by the traversing device 150, and is moved from the heating position St1 to the forming position St2. At the molding position St2, the mold 20 placed on the table 30 is placed on the lower elevator 130, and the upper mold 140 is closed in conjunction with the fixed upper elevator 120. A second camera is provided to take an image of the molding position St2. These devices are connected to a control device 80. Note that the control device 80 is omitted in FIGS. 9 to 11.

First, as shown in FIG. 8, in a state where the resin sheet SH held in the clamp frame 40 is carried by the traversing device 150 and stopped at the heating position St1, the first camera 71 captures an image to form a pre-molding image P1. get. After the resin sheet SH is heated by the hot plate 110 that has moved to the heating position St1, the clamp frame 40 is moved to the molding position St, and then the position with respect to the mold 20 is corrected using the position adjustment means. . Then, as shown in FIG. 10, the resin sheet SH is molded using a mold 20 at a molding position St2. Finally, after raising the upper elevator 120 and lowering the lower elevator 130 at the molding position St2, the molded product S1 is imaged by the second camera 72 to obtain a molded image P2.

In the thermoforming machine 100 having the above configuration, the position of the clamp frame 40 is corrected using the pre-molding image P1 and the post-molding image P2, as in the first embodiment. As a result, by using the thermoforming machine 100 of the second embodiment similarly to the first embodiment, it becomes possible to provide a highly accurate molded product S1.

Although the thermoforming machine 100 according to the present invention has been described above, the present invention is not limited thereto, and various changes can be made without departing from the spirit thereof. For example, in both the first embodiment and the second embodiment, the pattern Pa printed on the surface of the resin sheet SH is expressed as a grid-like line, and as another example, a circular mark Mk (on the pattern Pa) is expressed as a grid-like line. equivalent) is used. However, in addition to this, it is possible to select various shapes, characters, etc. as standards. In addition, the position adjustment using the position adjustment means used in the thermoforming machine 100 is not performed every time, but is performed at specific timings where misalignment is likely to occur, such as when starting the thermoforming machine 100 or when changing lots of resin sheets SH. You can operate it like this.

Further, in the first embodiment and the second embodiment, the position of the pattern Pa printed on the surface of the resin sheet SH with respect to the mold 20 is a problem, but the present invention deals with the position of the pattern Pa printed on the surface of the resin sheet SH with respect to the mold 20. It can also be applied to the case of adhesive covering molding. In this case, the base material is held against the mold 20 and the resin sheet SH having an adhesive layer is bonded to the base material, so as a result, the surface of the resin sheet SH against the mold 20 is It is the same in that the position of the printed pattern Pa matters.

SH Resin sheet Pa Pattern P1 Image before molding P2 Image after molding 10 Hot plate 20 Mold 40 Clamp frame 70 Camera

Claims (4)

In a thermoforming machine that shapes a pattern-printed resin sheet into a mold or adheres the resin sheet to a base material,
a frame body that positions, holds and conveys the resin sheet;
an imaging means for imaging the resin sheet;
position adjustment means for changing the position of the frame relative to the mold,
Before molding the resin sheet,
imaging the pattern of the resin sheet fixed to the frame with the imaging means to obtain a pre-molding image;
After molding the resin sheet,
imaging the pattern of the molded product obtained by molding the resin sheet using the mold with the imaging means to obtain a post-molding image;
The post-molding image is added to the data used in the position adjustment means for adjusting the position of the frame, and the first information obtained by detecting the amount of deviation from a predetermined reference position using the pre-molding image. using second information obtained by detecting the amount of deviation from the reference position;
A thermoforming machine featuring: The thermoforming machine according to claim 1,
The imaging means includes a first imaging means and a second imaging means,
The first imaging means is provided to take an image of the resin sheet at a heating position where heating is performed,
The second imaging means is provided to take an image of the resin sheet at a molding position where it is molded with the mold,
capturing the pre-molding image with the first imaging means, and capturing the post-molding image with the second imaging means;
A thermoforming machine featuring: The thermoforming machine according to claim 1,
the imaging means is provided to take an image of the resin sheet at a molding position where it is molded with the mold;
A thermoforming machine featuring: The thermoforming machine according to any one of claims 1 to 3,
checking the quality of the molded product using the post-molding screen;
A thermoforming machine featuring:

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