JPH0255452B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a corona discharge treatment device. [Background Art] For example, some automobile bumpers are made of polyolefin materials, and in order to improve their surface properties, corona discharge treatment has been conventionally performed. The equipment that performs this corona discharge treatment includes:
A discharge electrode wire is provided to face the base electrode. One type of discharge electrode is a rotating brush type. In this rotating discharge electrode, a large number of discharge electrode wires are planted around the outer periphery of a rotating body that rotates around a certain axis and can conduct electricity, and extend toward the outer diameter in a brush-like manner. However, although the conventional discharge electrode wires were installed in a spiral shape on the rotating body, their extending direction was set to be perpendicular to the outer periphery of the rotating body. When the discharge electrode wire extends in the perpendicular direction in this way, the tip of the discharge electrode wire will surely come into contact with the treated surface that is orthogonal to the discharge electrode wire, and discharge will occur effectively. This ensures that the tip of the discharge electrode wire does not come into contact with a surface that is perpendicular to the surface, that is, a surface that is parallel to the rotation locus surface of the discharge electrode wire. I couldn't do anything to process it. Among the planes perpendicular to the discharge electrode lines as mentioned above,
For example, there is a processed part that looks like a recess, and even if you try to contact the discharge electrode wire with such a recess, it is difficult to insert the tip of the discharge electrode wire all the way to the corner of the recess. I couldn't do it. This also applies to parts such as corners that rise up from recesses. [Object of the Invention] The present invention has been made in order to eliminate the above-mentioned disadvantages, and an object of the present invention is to provide a corona discharge treatment apparatus that enables more uniform and efficient discharge treatment of the entire object to be treated. It is an object. [Disclosure of the Invention] In order to achieve the above object, a corona discharge treatment apparatus according to the present invention includes a base electrode on which an object to be treated is provided, and a large number of discharge electrode wires extending in a radial direction around the outer periphery of a rotating body. The discharge electrode wires are connected to the object to be processed by rotation, and the surface of the object to be processed is heated by applying a high voltage between the two electrodes. In a corona discharge treatment device which is designed to be activated, the discharge electrode wires are installed in a spiral shape around the outer periphery of the rotating body, and each of the discharge electrode wires extends in a direction outward from the outer periphery of the rotating body. It is characterized by being inclined at a constant angle in a constant direction of the axial center of the rotating body with reference to a line extending perpendicularly to the radial direction. Hereinafter, the present invention will be explained in detail with reference to the drawings showing embodiments thereof. FIG. 1 shows an example of a corona discharge treatment apparatus according to the present invention, in which a transfer means 1
is assumed to be a conveyor belt, and the direction of arrow A is assumed to be its transport direction. On the transfer means 1, objects 2 to be processed made of polyolefin resin material, which are automobile bumpers, are placed at three locations in the longitudinal direction. The object to be processed 2 provided at the most trailing position in the transfer direction A is oriented so that its longitudinal direction is orthogonal to the transfer direction A, and the side that becomes the inner surface of the bumper faces downward. It is placed face down. The remaining object to be processed 2 is
It is oriented such that its longitudinal direction is parallel to the transport direction A and is also placed face down. As shown in FIG. 2, a plastic mold 4, which is a part of the base electrode 3, is provided on the inner surface of each object 2 to be processed. An electrically conductive metal layer 5 formed by electroless plating is provided between them. The base electrode 3 is constituted by the plastic mold 4 and the conductive metal layer 5. The base electrode 3 may be a mold made of an electrically conductive metal, for example aluminum. On the other hand, the discharge electrode side is entirely composed of rotating discharge electrodes 6. As shown in FIG. 3, this rotary discharge electrode 6 has a body in which a cylindrical rotating body 9 is fixed between a pair of a first support shaft 7 and a second support shaft 8 each having a flange. , a large number of discharge electrode wires 10 are arranged around the outer circumference of the rotating body 9.
It is provided so as to protrude in a brush-like manner. As shown in detail in Fig. 4, each discharge electrode wire 10 is not made of a single wire, but is made of a large number of stainless steel fibers a spun into a thread shape. is used.
A large number of discharge electrode wires 10 of the same length are prepared and implanted at implantation points b set on the outer periphery of the rotating body 9, as shown in FIG. The implantation points b are sequentially set at constant small intervals on the spiral line S, and the discharge electrode wire 10 implanted at the implantation point b is perpendicular to the outer periphery of the rotating body 9. It extends so as to be inclined at a slight angle (projection angle) θ in one direction along the center line O of the rotating body 9 with respect to the vertical reference line c erected as shown in FIG. As shown in Figure 5, the discharge electrode wire 10 is actually weak and fragile because it is made of fine fibers twisted together, rather than something that stands up quickly like a piano wire. In a state where it is in a state where it is worn out, it gradually rises as it rotates, as shown by the solid line in Figure 5, and furthermore, when it is subjected to a greater centrifugal force, it gradually rises up as it rotates, and furthermore, as it is subjected to greater centrifugal force, it rises as shown by the two-dot chain line (see also Figure 12). It is designed to be in a bowed state as seen in . For example, as shown in FIG. 6, the rotary discharge electrode 6 is rotatably mounted on a support frame 11 by a pair of plummer blocks 13 via an insulating material 12 (made of baked or Teflon material). A current carrying bearing 14 is attached to one end, and a pulley 17 driven by a belt (insulator) by a variable speed motor 16 with an insulating material 15 is attached to the other end. . As shown in FIG. 1, this rotary discharge electrode 6 moves upward while the tip of the discharge electrode wire 10 rotates and comes into contact with the rising outer surface of both ends of the bumper in the longitudinal direction of the first object to be processed 2. (or move horizontally in the transport direction A). The rotary discharge electrode 6 rises along the rising outer surface of the object to be treated 2, and the object to be treated 2 is fixedly placed on the transfer means 1, but the rotary discharge electrode 6 is of a stationary type in which it does not rise. , the object to be processed 2 can also be configured to rise. In this embodiment, four rotating discharge electrodes 6 are prepared, one pair of which is arranged on each outer surface, and the centers of rotation are all parallel to (or perpendicular to) the transfer direction A. It is directed like this. This rotary discharge electrode 6 is in a fixed position when viewed from above, and moves upward while rotating on the outer surface of the object to be processed 2 being transferred, thereby generating an electric current between it and the base electrode 3. The structure is configured so that a corona discharge is generated using a high voltage applied to the outer surface, and the outer surface is subjected to a discharge treatment. This processing zone is here a rising processing zone 30.
It is called. A side processing zone 31 is provided on the transfer direction A side of the rising processing zone 30.
In this zone 31, the object to be processed 2 is provided with its longitudinal direction parallel to the transport direction A, and is configured so that both sides of the object to be processed 2 in the longitudinal direction are subjected to discharge treatment. Each rotary discharge electrode 6 is arranged with its center of rotation parallel to (or at right angles to) the transfer direction A, with three rotary discharge electrodes 6 corresponding to each side. The next upper surface treatment zone 32 is configured to perform discharge treatment on the upper surface of the object 2 to be treated in its original orientation. Each rotating discharge electrode 6
are arranged on the upper surface 23 with their rotation centers perpendicular to (or parallel to) the transport direction A. Next, various conditions for the discharge electrode wire 10 to contact the surface of the object to be processed 2 more effectively will be explained as an example. One of them is the projection angle θ. As shown in FIG. 7, this angle θ is set so that the tip of the discharge electrode wire 10 can more reliably come into contact with the bottom corner 19 of the recess 18 formed in the object 2 to be processed. For example, when the groove width W of the recessed part 18 is in the range of 10 to 55 mm (actual measurement), the length L of the discharge electrode wire 10 is 100 mm and 150 mm.
When performing discharge treatment using each type individually, if a discharge electrode wire 10 with a length L of 100 mm is used, if θ is in the range of approximately 6 to 30 degrees, the recessed portion 1
It is possible to touch the corner 19 of 8, and the length L is
When a 150 mm discharge electrode wire 10 was used, contact was possible within a range of θ of about 5 to 20 degrees. Regarding the angle θ, other conditions are also related, but if the angle θ is too small, the discharge electrode wires 10 tend to overlap and become tangled, resulting in a decrease in processing efficiency, while if the angle θ is too large, the processing effect will be affected. decreases. Also,
The implantation density of the discharge electrode wires 10 is as follows:
Although it varies somewhat depending on the composition of the discharge electrode wire 10 itself, when the discharge electrode wire 10 is divided into 2, 4, 10, 20, or 40 wires per unit length and the discharge treatment is performed individually,
At planting densities of 2 and 4 plants/cm, there was a risk of uneven treatment, whereas at planting densities of 20 plants/cm
With the above implantation density, the discharge electrode wires 10 become entangled with each other, making it impossible to perform sufficient discharge treatment on details such as the corners 19 of the recessed portions 18. Based on these facts, it has been empirically determined that the implantation density is about 10 plants/cm as the optimal value for effective discharge treatment. As shown in FIG. 8, the discharge electrode wire 10
It is also necessary to set the tip so that it contacts the entire surface of the object to be processed 2 thoroughly. This corresponds to the discharge electrode wires 1 adjacent to each other in the axial direction of the rotating body 9.
The element determined by the spiral pitch P between 0 and 10 is large. As mentioned above, the discharge electrode wire 1
If two types of length 100 mm and 150 mm are used as 0 and discharge processing is performed with the projection angle θ set to 5 to 30 degrees, the discharge electrode wire 10 with L of 100 mm is used with θ of 5 degrees. If the pitch P is set to approximately 13 mm, the overlap between the effective processing ranges d and d will be 0, and if the length L is 150 mm and θ is 30 degrees, the pitch P will be approximately 50 mm. It was found that the overlap becomes 0. As a result, PitzchiP
If the pitch P is in the range of 13 to 50 mm, discharge treatment can be carried out completely, but if the pitch P is too narrow, the discharge electrode wires 10 will become entangled with each other, reducing the treatment effect. It has been found that if is too large, blank areas occur and processing efficiency decreases. The effective processing ranges d and d are taken in the direction perpendicular to the direction in which the discharge electrode wire 10 rotates, that is, in the width direction of the rotating body 9, but as shown in FIG. Processing range e
It is also necessary to evaluate. Therefore,
The discharge electrode wire 10 is implanted at a θ of approximately 10°, a spiral pitch P of 40 mm, and a planting density of 10 wires/cm, and as shown in FIGS. 10 and 11, the half circumference in the circumferential direction is from a radius of 100 mm. A discharge electrode 6 was used in which the length was increased to 150 mm, and the length of the remaining half circumference was shortened from 150 mm to 100 mm. As shown in Figure 9, the center of rotation is set at a height of 100 mm from the object 2, which is a PP board, and
Discharge treatment was performed at a rotation speed of 100 rpm and an applied voltage of 24 KV. In this case, when the treatment time was 15 seconds and 30 seconds, the effective treatment range in which a peel strength of 1000 g/cm or more was obtained was 20 mm and 90 mm, respectively. When the same treatment was performed using discharge electrode wires all of uniform length under the conditions that the treatment time was 15 seconds and the effective treatment range e was 60 mm, the same peel strength as described above was obtained. Due to these factors, processing time is shortened (processing efficiency is increased).
For example, in the case of the bumper mentioned above, if the longitudinal length of the bumper is 1800 mm, arranging 30 rotating discharge electrodes will achieve the maximum treatment. It was also found that efficiency can be achieved. Furthermore, there is a condition regarding the number of rotations in order to increase the processing effect. In other words, if the rotation speed is too low, the centrifugal force is small and the ability to penetrate into the recessed portion 18 is poor, while if it is too high, the discharge electrode wire 10 may come into too strong contact with the object to be processed 2 and be damaged. Therefore, the rotation speed is generally
A range of about 30 to 300 rpm is preferable. In this way, the discharge electrode wire of the rotating discharge electrode does not extend perpendicularly from the rotating body, but is slanted in the axial direction of the rotating body, so that it can extend even to the side of the object to be treated. Not only can discharge treatment be performed at the same time, but the tip of the electrode wire can also reach recesses and sharp corners, making it possible to perform discharge treatment efficiently. Note that the discharge electrode wires may be planted in combinations of different lengths, for example, so that the length of the discharge electrode wires decreases as one goes half a turn along the spiral, but returns to the original length in the next half turn. If provided, there will be no tangles, and even if there is a slight difference in the distance to the object to be processed, the number of tips touching the object will be uniform.
In the processing line, the object to be processed and the base electrode may rotate up and down and back and forth, while the rotary discharge electrode may be configured to rotate at a fixed position. The structure in which the discharge electrode wire 10 is implanted may be as shown in FIG. 12, for example. In other words, by using a spiral-shaped (coil spring-shaped) first rotating member 20 having a cross section that is approximately U-shaped with the opening side of the groove widened, and a second rotating member 21 having a similar structure. , so that they screw together and fit between each other's spirals,
A rotating body 9 is formed. The first and second rotating members 20 and 21 are fitted into each other by a spring force so as to be adjacent to each other, and between the adjacent rotating members, approximately U
A spiral-shaped (coil spring-shaped) electrode wire holding member 22 having a letter-shaped cross section is similarly screwed into the electrode wire holding member 22 . The base of the discharge electrode wire 10 is attached to the U-shaped groove of the electrode wire holding member 22 by caulking. Since the electrode wire holding member 22 is formed in a spiral shape, it is advantageous for normal assembly, and of course, it is also advantageous for attaching and detaching when using the above option. The angle θ is the angle between the first and second rotating members 20 and 21.
The size can be set by adjusting the rising angle α of the flanges 20a and 21a. 13 and 14 show each part A to F of the object to be processed, which is a bumper.
The figure shows a cross-sectional view perpendicular to the longitudinal direction of the bumper.
FIG. 14 shows their plan views. Part A is the first upper surface which is one side of the upper surface, part B
is the upper surface groove, part C is the second upper surface, part D is the first recessed surface of the recessed part, and part E is the second recessed surface adjacent to part D.
The surface and region F represent the recessed third surface facing region D, respectively. For each of these parts A to F, there is a first discharge electrode in which discharge electrode wires of equal length are implanted, and a discharge electrode that is sequentially longer in half the circumference and becomes sequentially shorter in the remaining half circumference, as shown in Fig. 9. The difference in peel strength (g/cm) was measured using a second discharge electrode with a wire installed under conditions of a voltage of 25 KV and a treatment time of 15 seconds. The results are shown in Table 1.

〔Effect of the invention〕

As seen above, the corona discharge treatment apparatus according to the present invention includes a base electrode on which the object to be treated is provided, and a large number of discharge electrode wires that are planted on the outer periphery of the rotating body so as to extend in the radial direction. The electrode wire is provided with a discharge electrode connected to the object to be treated by rotation, and the surface of the object to be treated is activated by applying a high voltage between the two electrodes. In the corona discharge treatment apparatus, the discharge electrode wires are installed in a spiral around the outer periphery of the rotating body, and each extending direction is based on a line extending from the outer periphery of the rotating body at right angles to the outer shape direction. As a result, the entire object to be treated can be subjected to the discharge treatment more uniformly and efficiently.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a corona discharge treatment apparatus according to the present invention, Fig. 2 is an explanatory view showing a state in which an object to be treated is subjected to discharge treatment, and Fig. 3 shows a rotating discharge electrode. 4 is a front view showing the details of the discharge wire, FIG. 5 is an explanatory diagram showing the discharge wire installed in the rotating body, and FIG. 6 is the mounting state of the rotating discharge electrode. Figure 7 is a cross-sectional view to explain the reason for setting the projection angle, Figure 8 is a front view to explain the reason for setting the spiral pitch, and Figure 9 is an effective process along the rotation direction. Side view to explain the range,
Fig. 10 is a side view of a rotating discharge electrode equipped with discharge electrode wires of different lengths in the circumferential direction, Fig. 11 is a front view thereof, and Fig. 12 is a structure in which the rotating body is used as a spiral member to hold the electrode. FIG. 13 is a cross-sectional view of the bumper used when comparing peel strength using two different types of discharge electrodes, and FIG. 14 is a plan view of the bumper seen from above. 2...Object to be treated, 3...Base electrode, 9...Rotating body, 10...Discharge electrode wire.

Claims (1)

[Claims] 1. A base electrode on which an object to be treated is provided, and a large number of discharge electrode wires are planted so as to extend in a radial direction on the outer periphery of a rotating body, and these discharge electrode wires are connected to the object to be treated by rotation. In a corona discharge treatment apparatus, which is equipped with rotating discharge electrodes that are in contact with each other, and the surface of a target object is activated by applying a high voltage between the two electrodes. , the discharge electrode wires are installed in a spiral shape around the outer periphery of the rotating body, and the direction in which each of the discharge electrode wires extends is aligned with the axis of the rotating body with reference to a line extending from the outer periphery of the rotating body at right angles to the outer diameter direction. A corona discharge treatment device characterized in that the device is inclined at a certain angle in a certain direction from the center. 2. The corona discharge treatment apparatus according to claim 1, wherein the discharge electrode is constructed by alternately arranging two types of discharge electrode wires having different lengths. 3. Claim 1, wherein the discharge electrode wires are arranged so that their lengths gradually become shorter between half turns in the rotational direction, and are arranged so that their lengths gradually become longer during the remaining half turns. The corona discharge treatment device described. 4. The corona discharge treatment device according to any one of claims 1 to 3, wherein the discharge electrode wire is made of twisted metal fibers. 5. The corona discharge treatment apparatus according to claim 4, wherein the metal fiber is made of stainless steel. 6 The rotating body is formed in a spiral shape,
Claims 1 to 5 further include an electrode wire holding member formed in a spiral shape being sandwiched between the spirals, and a discharge electrode wire embedded in the electrode wire holding member. The corona discharge treatment device according to any one of items 5 to 5. 7. The corona discharge treatment apparatus according to claim 6, wherein the electrode wire holding member has a U-shaped cross section, and the base of the discharge electrode wire is sandwiched between the U-shaped portions. 8. A plastic mold is provided at the bottom of the object to be processed, a conductive metal layer is provided between the plastic mold and the object to be processed, and a base electrode is constituted by the plastic mold and the conductive metal layer. A corona discharge treatment apparatus according to any one of claims 1 to 7. 9. The corona discharge treatment apparatus according to claim 8, wherein the conductive metal layer is provided by electroless plating. 10. The corona discharge treatment apparatus according to claim 8 or 9, wherein the base electrode is constituted by a mold made of aluminum. 11. The corona according to any one of claims 1 to 10, in which the object to be treated is capable of changing its posture, and the rotating discharge electrode is installed in a fixed position. Discharge treatment equipment.