Method for detecting residual material

Abstract

The present invention provides a method for detecting leftover material on a mesh conveyor that can reliably detect the presence of leftover material on the conveyor in a simple and rapid manner without requiring any learning or other effort. [Solution] In a mesh conveyor 1 in which a metal mesh belt 13 is stretched between two axes 11 and rotates to transport a workpiece W1 placed on the metal mesh belt 13, the presence of residual material in the mesh conveyor 1 is detected by irradiating the portion of the metal mesh belt 13 that has passed through the region where gravity acts on the workpiece W1 with focused light L at an angle in which no direct reflected light from the portion of the metal mesh belt 13 is substantially generated, and acquiring an image including the irradiated region R.

Description

[Technical Field]

[0001] The present invention relates to a residual workpiece detection method, and particularly relates to a residual material detection method for detecting the presence of a workpiece remaining on a mesh conveyor without falling and separating therefrom. [Background Art]

[0002] As a conveyor for conveying workpieces that have undergone forging, heat treatment, or the like, mesh conveyors excellent not only in heat resistance but also in dehydration and air permeability are used. However, if the workpiece is a thin article, or the metal mesh is deteriorated and frayed, the workpiece may be caught in the gaps of the metal mesh or caught on the frays, remain as residual material on the mesh conveyor without falling and separating therefrom, and mix as a foreign material into newly supplied workpieces of different model numbers.

[0003] Accordingly, in order to detect the presence of residual material, it is conceivable to capture an image of the conveyor with a camera. However, since the metal mesh of the mesh conveyor easily reflects illumination light, if article detection (residual material detection) is performed facing the conveyor surface directly as disclosed in Patent Document 1, for example, the presence or absence of residual material in the captured image cannot be reliably determined due to interference from reflected light. It is also conceivable to use AI for determination to improve the detection accuracy of residual material, but there is a problem that the amount of learning for AI becomes excessive. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-39719 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and to provide a residual material detection method capable of easily and quickly reliably detecting the presence of residual material on a mesh conveyor without requiring labor such as learning. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a mesh conveyor (1) in which a metal mesh belt (13) is stretched between two axes (11) and rotates to transport a workpiece (W1) placed on the metal mesh belt (13). The present invention detects the presence of residual material on the mesh conveyor (1) by irradiating the portion of the metal mesh belt (13) that has passed through a region where gravity acts on the workpiece (W1) with focused light (L) at an angle in which no direct reflected light from the portion of the metal mesh belt (13) is substantially generated, and acquiring an image including the irradiated area (R). A preferred example of the "angle in which no direct reflected light from the portion of the metal mesh belt is substantially generated" is when the workpiece (W1) is transported forward by the upper metal mesh belt (13) of the mesh conveyor (1), and focused light (L) is irradiated at a horizontal angle from an illuminator (2) located behind the mesh conveyor (1) to the portion of the metal mesh belt (13) that passes through the upper rear corner of the mesh conveyor (1).

[0007] According to the present invention, since focused light is irradiated onto the portion of the metal mesh belt that has passed through the region where gravity acts on the workpiece, at an angle in which substantially no direct reflected light is generated, an image including the irradiated region is acquired. Therefore, if residual material remains on the metal mesh belt, a good and reliable image of the residual material can be obtained without interference from reflected light from the metal mesh belt portion, and necessary measures such as stopping the mesh conveyor can be taken promptly.

[0008] Preferably, the metal mesh belt portion is located at the upper corner of the end of the mesh conveyor (1) where the metal mesh belt changes direction from upward to horizontal.

[0009] Furthermore, it is preferable that the focused light (L) is either a line-shaped focused light extending in the belt width direction, or a spot-shaped focused light arranged in parallel in the belt width direction.

[0010] The symbols in parentheses above are for reference only, indicating the correspondence with the specific means described in the embodiments described later. [Effects of the Invention]

[0011] As described above, the residual material detection method of the present invention allows for the simple, rapid, and reliable detection of residual material on a mesh conveyor without requiring any learning or other effort. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic partial side view showing an example of an apparatus arrangement for implementing the method of the present invention. [Figure 2] This is a perspective view of the camera device. [Figure 3] This is a schematic partial side view of the residual material detection process. [Figure 4] This figure shows an example of an image showing the detection of residual material. [Figure 5] This figure shows another example of a residual material detection image. [Modes for carrying out the invention]

[0013] The embodiments described below are merely examples, and various design improvements made by those skilled in the art without departing from the spirit of the present invention are also included within the scope of the present invention.

[0014] Figure 1 shows an example of the apparatus arrangement for carrying out the method of the present invention. Figure 1 shows the rear end of the mesh conveyor 1. The mesh conveyor 1 is a known structure in which chain members provided on both sides of a metal mesh belt 13 of a constant width are suspended from sprockets 12 provided on each of the rotating shafts 11 at the front end (not shown) and rear end, and the belt 13 is rotated. In the mesh conveyor 1 shown in Figure 1, the metal mesh belt 13 rotates counterclockwise as indicated by the arrow.

[0015] In Figure 1, a workpiece supplied and placed on the upper metal mesh belt 13, which extends to the left, at a position not shown in the figure, is transported in the same direction as the belt 13 rotates. At the front end of the mesh conveyor 1 (not shown), gravity acts on the metal mesh belt 13 as it changes direction downward, causing it to fall off the belt 13. Gravity also acts on the workpiece as it changes direction from downward to backward and is transported on the lower metal mesh belt 13, and at the rear end where it changes direction from backward to upward, causing the workpiece to fall off the metal mesh belt 13 during these times as well.

[0016] However, if the workpiece is a thin item, it may get caught in the gaps of the metal mesh belt 13, or if the metal mesh belt 13 has deteriorated and is frayed, the workpiece may get caught on the frayed parts, remaining attached to the metal mesh belt 13 without falling off. At the rear end of the mesh conveyor 1, the metal mesh belt 13 changes direction from above to horizontal and the workpiece remains attached to the metal mesh belt 13 as residual material in the belt section that is once again on the upper side.

[0017] If residual material adheres to the metal mesh belt 13 in this manner, there is a risk that the residual material may be mixed as foreign material with workpieces of different model numbers that are newly supplied to the upper metal mesh belt 13. Therefore, in this embodiment, as shown in Figure 1, a light fixture 2 installed at the rear of the mesh conveyor 1 emits multiple spot-shaped focused beams L in parallel in the belt width direction, horizontally towards the upper rear corner of the mesh conveyor 1 through which the metal mesh belt 13 passes. The emitted spot-shaped focused beams L pass straight forward if the workpiece is not within the irradiation area R, or are reflected diagonally upward and backward, with almost no reflection towards the rear light fixture 2. Alternatively, instead of spot-shaped focused beams L, line-shaped focused beams extending in the belt width direction may be emitted horizontally.

[0018] In this state, as indicated by the thin lines in Fig. 1, an area including the light irradiation region R at the upper rear corner portion of the mesh conveyor 1 is imaged by the camera device 3 provided on the same side as the illuminator 2. As shown in Fig. 2, the camera device 3 is configured such that a Peltier element cooling unit 32 is provided inside a rectangular housing 31 having a HEPA filter 311 disposed on the outer wall thereof, and a smart camera 33 is disposed on the cooling unit 32. A lens portion 331 of the smart camera 33 protrudes from the housing 31, and a hot mirror 332 is attached to a distal end of the lens portion 331.

[0019] An example of the workpiece (W1) in the present embodiment is a 15-mm-thick ring-shaped steel material at 500°C to 600°C after hot forging. When the workpiece W1 appears as residual material adhering to the metal mesh belt 13 in the light irradiation region R at the upper rear corner portion of the mesh conveyor 1 (Fig. 3), the reflected light from the metal mesh belt 13 is suppressed to such a small level that substantially no reflected light is generated. Therefore, without being obstructed thereby, only the reflected light from the workpiece W1 returns to the camera device 3 at the rear, and the workpiece W1 is clearly captured in the captured image (within the circle in Fig. 4). This makes it possible to reliably determine the presence or absence of residual material.

[0020] Another example of the workpiece (W2) in the present embodiment is a small-diameter metal cylinder after normalizing. Also in this case, as shown in Fig. 5, when the workpiece W2 appears as residual material adhering to the metal mesh belt 13 in the light irradiation region R at the upper rear corner portion of the mesh conveyor 1, as shown within the circle in Fig. 5, the workpiece W2 is clearly captured in the image captured by the camera device 3 without being obstructed by reflected light from the metal mesh belt 13, whereby the presence or absence of residual material can be reliably determined. Description of Reference Signs

[0021] 1... mesh conveyor, 13... metal mesh belt, L... convergent light, R... irradiation region, W1, W2... workpiece.

Claims

1. A method for detecting residual material in a mesh conveyor, in which a metal mesh belt is stretched between two axes and rotates to transport a workpiece placed on the metal mesh belt, by irradiating the portion of the metal mesh belt that has passed through a region where gravity acts on the workpiece with focused light at an angle at which no direct reflected light from the portion of the metal mesh belt is substantially generated, and acquiring an image including the irradiated area.

2. The residual material detection method according to claim 1, wherein the metal mesh belt portion is located at the upper corner of the end of the mesh conveyor where the metal mesh belt changes direction from an upward direction to a horizontal direction.

3. The residual material detection method according to claim 1, wherein the focused light is a line-shaped focused light extending in the belt width direction.

4. The residual material detection method according to claim 1, wherein the focused light is a series of spot-shaped focused lights arranged in parallel in the belt width direction.

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