Trivalent chromium plating apparatus for cylinder and method, and method for manufacturing gravure cylinder

Abstract

The present invention provides a trivalent chromium plating apparatus and method for rollers that uses a trivalent chromium plating solution, which does not produce unprecipitated portions of the plating material, and enables trivalent chromium plating with good precipitation, uniformity, and excellent brush resistance. A trivalent chromium plating apparatus for a roller includes: a plating tank storing a trivalent chromium plating solution; a clamping means that holds both ends of the roller to be processed in a rotatable and energized manner and accommodates it in the plating tank in a horizontal direction; and an insoluble electrode that is energized at a predetermined time so that the insoluble electrode approaches the outer peripheral surface of the roller to be processed at a predetermined interval, and performs trivalent chromium plating on the outer peripheral surface of the roller. The insoluble electrode is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller to be processed.

Description

[Technical Field]

[0001] The present invention relates to a trivalent chromium plating apparatus and method for applying trivalent chromium plating with an insoluble electrode to the outer peripheral surface of a long strip-shaped hollow roller when manufacturing a hollow cylindrical gravure roller (also known as a plate-making roller) used for, for example, gravure printing. [Previous Technology]

[0002] In gravure printing, a printing plate is created by forming tiny recesses (units) in a hollow cylindrical roller according to the plate-making information. Ink is then filled into these units and transferred to the substrate. A typical gravure roller uses a cylindrical iron or aluminum core (hollow roller) as its base material. Multiple layers, such as an underlayer and a release layer, are formed on the outer surface of this base material, and a copper plating layer is formed on top of this. Furthermore, units corresponding to the plate-making information are formed in this copper plating layer using a laser exposure device. Then, chrome plating or similar processes are performed to increase the brush resistance of the gravure roller, thus completing the plate-making process. This typical chrome plating is a hexavalent chromium plating layer.

[0003] However, since the chromium plating process uses highly toxic hexavalent chromium plating solution, in addition to the extra cost of ensuring operational safety, there is also the problem of pollution. The current expectation is for the emergence of a surface strengthening coating to replace the hexavalent chromium layer.

[0004] As an alternative to the plating method for obtaining a hexavalent chromium plating layer from a hexavalent chromium plating solution, there is a trivalent chromium plating method for forming a chromium plating layer using a trivalent chromium plating solution. For example, the trivalent chromium plating solution shown in Patent Document 1 is an example of such a solution.

[0005] In addition, the applicant has also proposed a plating apparatus for a roller, comprising: a plating tank for storing plating solution; a clamping means for holding the two ends of the roller to be processed in a rotatable and energized manner and housing them in the plating tank; and a pair of opposing insoluble electrodes, which are vertically arranged facing the two sides of the roller to be processed in the plating tank and are energized in a predetermined manner, so that the pair of insoluble electrodes approach the two sides of the roller to be processed at a predetermined interval, thereby plating the outer peripheral surface of the roller to be processed. The insoluble electrode has a shape in which at least the lower part is bent inward and at least the lower part is made into a comb-shaped portion. The insoluble electrodes are arranged such that the protrusion of the comb-shaped portion of the other insoluble electrode is located in the position of the concave portion of the comb-shaped portion of the other insoluble electrode. The insoluble electrodes are arranged to face each other alternately, and the upper end of the insoluble electrode is divided into a rotation center so that the insoluble electrode can be rotated. The insoluble electrode can be adjusted to adjust the approach distance between the insoluble electrode and the outer peripheral surface of the roller being processed according to the diameter of the roller being processed (Patent Document 2).

[0006] In the plating apparatus for rollers in Patent Document 2, if a general chromium plating solution of hexavalent chromium plating solution is used, a chromium plating layer (hexavalent chromium plating layer) with excellent brush resistance that meets the surface properties required for gravure printing, namely hardness, wear resistance and uniform electrodeposition, can be obtained.

[0007] However, in the plating apparatus for a drum in Patent Document 2, if trivalent chromium plating using a trivalent chromium plating solution is performed, as shown in the photograph in FIG11, a black portion is produced in the central part of the drum. This is a state where the plating material has hardly precipitated, resulting in an unprecipitated portion on a part of the drum. Thus, in the plating apparatus for a drum in Patent Document 2, if trivalent chromium plating using a trivalent chromium plating solution is performed, there is a problem that an unprecipitated portion is produced on a part of the drum. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-123927 [Patent Document 2] WO2015 / 151665 [Summary of the Invention]

[0009] [The problem the invention aims to solve]

[0010] This invention was developed in view of the aforementioned problems in the prior art, and its object is to provide a trivalent chromium plating apparatus and method for rollers that uses a trivalent chromium plating solution, does not produce unprecipitated portions of the plating material, and enables trivalent chromium plating with good, uniform precipitation and excellent brush resistance. [Technical Means for Solving the Problem]

[0011] The trivalent chromium plating apparatus for a roller of the present invention comprises: a plating tank for storing trivalent chromium plating solution; a clamping means for holding both ends of the roller to be processed in a rotatable and energized manner and accommodating them in the plating tank in a horizontal direction; and an insoluble electrode for being energized in a predetermined manner so that the insoluble electrode approaches the outer peripheral surface of the roller to be processed at a predetermined interval, and for performing trivalent chromium plating on the outer peripheral surface of the roller, wherein the insoluble electrode is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller to be processed.

[0012] The aforementioned surrounding insoluble electrode preferably includes a lower surrounding insoluble electrode surrounding the lower outer peripheral surface of the roller to be treated, which is horizontally housed in the aforementioned plating tank, and / or an upper surrounding insoluble electrode surrounding the upper outer peripheral surface of the roller to be treated, which is horizontally housed in the aforementioned plating tank.

[0013] The aforementioned upper surrounding insoluble electrode and / or the aforementioned lower surrounding insoluble electrode are preferably cross-type electrodes.

[0014] The aforementioned surrounding insoluble electrode is preferably positioned close to the outer circumferential surface by means of a cylinder or electric motor, depending on the diameter of the roller being processed.

[0015] The aforementioned surrounding insoluble electrode is preferably made to approach the outer peripheral surface by rotating the arm or widening or narrowing the gap, in accordance with the diameter of the roller being processed.

[0016] The trivalent chromium plating method of the present invention is a trivalent chromium plating method that uses the aforementioned trivalent chromium plating apparatus for rollers and the aforementioned trivalent chromium plating solution to perform plating treatment on the aforementioned roller to be treated.

[0017] The method for manufacturing a gravure cylinder of the present invention involves using the aforementioned trivalent chromium plating apparatus for cylinders to plate the aforementioned cylinder with the aforementioned trivalent chromium plating solution, thereby manufacturing a gravure cylinder. [Effects of the Invention]

[0018] According to the present invention, the following significant effects can be achieved, namely, a trivalent chromium plating apparatus and method for rollers that can perform uniform and brush-resistant trivalent chromium plating using a trivalent chromium plating solution.

Implementation Method

[0020] The following description of the embodiments of the present invention is based on the figures. However, the figures are only examples to illustrate the present invention. Various modifications can be made to the present invention without departing from the scope of the technical concept of the present invention.

[0021] In Figures 1 and 2, the first embodiment of the trivalent chromium plating apparatus for rollers of the present invention is shown, which is the trivalent chromium plating apparatus 10A for rollers.

[0022] The trivalent chromium plating apparatus 10A for rollers of the present invention is a plating apparatus for performing trivalent chromium plating on a roller 12 to be processed. The trivalent chromium plating apparatus 10A for rollers of the present invention comprises: a plating tank 14 for storing trivalent chromium plating solution; a clamping means 16 for holding the roller to be processed at both ends in the length direction in a rotatable and energized manner and accommodating it in the plating tank in the horizontal direction; and an insoluble electrode 18 for performing trivalent chromium plating on the outer peripheral surface of the roller 12 to be processed by applying a predetermined energization. The insoluble electrode 18 is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller 12 to be processed.

[0023] The aforementioned surrounding insoluble electrode 18 comprises: a lower surrounding insoluble electrode 22 surrounding the lower outer peripheral surface 20 of the roller 12 to be processed, which is horizontally housed in the plating tank 14, and / or an upper surrounding insoluble electrode 26 surrounding the upper outer peripheral surface 24 of the roller 12 to be processed, which is horizontally housed in the plating tank 14. Figure 1 shows an example including both the lower surrounding insoluble electrode 22 and the upper surrounding insoluble electrode 26.

[0024] Furthermore, the surrounding insoluble electrode used in the trivalent chromium plating apparatus for the roller of the present invention is preferably the aforementioned surrounding insoluble electrode 18 or a mesh electrode including the surrounding insoluble electrode described later. This is because when it is a mesh electrode, an electric field is generated not only on the surface of the aforementioned surrounding insoluble electrode but also on its back side. Therefore, the surface area of ​​the aforementioned surrounding insoluble electrode as an electrode increases, resulting in a decrease in the current density of the aforementioned surrounding insoluble electrode and a longer service life. As a mesh electrode, the mesh electrode described in Patent Document 2 is preferred.

[0025] In the trivalent chromium plating apparatus 10A for drums, the aforementioned lower-side surrounding insoluble electrode 22 is a cross-type electrode. In this specification, a cross-type electrode refers to an electrode in which a group of insoluble electrodes with comb-shaped ends intersect each other. That is, it is an electrode formed by intersecting each other in such a way that the protrusion of the comb-shaped portion of one of the lower-side surrounding insoluble electrodes (22a, 22b) is located at the position of the concave portion of the comb-shaped portion of one of the lower-side surrounding insoluble electrodes 22a.

[0026] Furthermore, the aforementioned upper surrounding insoluble electrode 26 of the aforementioned surrounding insoluble electrode 18 is moved up and down by the cylinder 28, so that the diameter of the aforementioned processed roller 12 is close to the aforementioned outer peripheral surface. Alternatively, instead of the cylinder 28, an electric motor can be used to move the aforementioned upper surrounding insoluble electrode 26 up and down, so that the diameter of the aforementioned processed roller 12 is close to the aforementioned outer peripheral surface.

[0027] Furthermore, the aforementioned lower surrounding insoluble electrode 22 of the aforementioned surrounding insoluble electrode 18 is adjusted by the rotational movement of the arms 30a and 30b to position the protrusion of the aforementioned comb-shaped portion of the aforementioned lower surrounding insoluble electrode 22b into the concave portion of the aforementioned lower surrounding insoluble electrode 22a, so that the diameter of the aforementioned processed roller 12 is close to the aforementioned outer peripheral surface.

[0028] Conventionally, as shown in Patent Document 2, the electrodes are located only on the lower portion of the processed roller in a set horizontal direction. However, in this invention, the electrodes are arranged on the upper side of the processed roller 12 in a manner that covers the processed roller 12. That is, the electrodes are characterized by being arranged around the entire circumference of the processed roller 12. Furthermore, in the example shown in the figures, the upper surrounding insoluble electrode 26 and the lower surrounding insoluble electrode 22 are powered by the same power source. In addition, the diameter of the processed roller 12 varies, but by moving the upper surrounding insoluble electrode 26 and the lower surrounding insoluble electrode 22, it is possible to adapt to processed rollers 12 of various diameters.

[0029] By adopting the aforementioned structure, even when performing trivalent chromium plating using a trivalent chromium plating solution, there is no problem of unprecipitated portions forming on a part of the processed roller 12, resulting in a roller with good, neat, and uniform precipitation and excellent brush resistance. Due to its excellent brush resistance, it can be used as a gravure roller. In addition, compared to the roller plating apparatus shown in Patent Document 2, which has an electrode only on the lower side, the trivalent chromium plating apparatus 10A for rollers also has the effect of reducing voltage by approximately 50%.

[0030] As a trivalent chromium plating solution, the plating solution described in Patent Document 1 can be used. Hexavalent chromium, in particular, is toxic; therefore, a trivalent chromium plating solution containing trivalent chromium, such as chromium trichloride (CrCl3 (CrCl3·6H2O)), is preferred. Furthermore, as described in Patent Document 1, as a solution of chromium trichloride, a chloride solution (calcium chloride or lithium chloride) is preferred, as it does not use water; a solution containing a high concentration of dissolved calcium halide is preferable. Additionally, a solution with a specific decomposition potential, as described in Patent Document 1, is preferred as the plating solution.

[0031] The aforementioned treated roller 12 is housed in the aforementioned plating tank 14 in a horizontal direction. That is, the plating apparatus of the present invention is a horizontal plating apparatus that houses the treated roller 12 laterally. In the case of a horizontal plating apparatus, if an electrode is provided on the upper side of the treated roller 12, it will be a problem to remove or place the treated roller 12 into the aforementioned plating tank 14. However, by using a cylinder 28 to move the upper surrounding insoluble electrode 26 up and down, the problem of removing or placing the treated roller 12 into the aforementioned plating tank 14 can be solved.

[0032] Alternatively, a vertical plating apparatus could be considered, in which the roller 12 to be treated is housed longitudinally in the plating apparatus. However, even if electrodes such as cylinders are arranged around the vertically upright roller 12, trivalent chromium plating cannot be performed neatly. As a problem with such a vertical plating apparatus, since the plating solution accumulates from the bottom of the plating tank, the immersion time of the roller in the trivalent chromium plating solution differs between the top and bottom. Because the trivalent chromium plating solution is acidic, the surface of the roller may be corroded or become rough.

[0033] Furthermore, if it is made into a vertical plating apparatus, during the period when the plating solution accumulates from the bottom of the plating tank, it will be in a state of electroless plating. Therefore, if the plating solution contains impurities such as Ni or Fe, there is a problem that impurities will be precipitated on the surface of the treated drum simply by immersing it in the plating solution.

[0034] Since the plating apparatus of the present invention is a horizontal plating apparatus that is housed in the aforementioned plating tank 14 in a horizontal direction, the plating liquid can be placed in the state of the rotating roller 12, so the problem of only a part of the roller surface being rough can be avoided.

[0035] Next, in Figures 3 and 4, a second embodiment of the trivalent chromium plating apparatus for rollers of the present invention is shown, showing the trivalent chromium plating apparatus 10B for rollers.

[0036] The trivalent chromium plating apparatus 10B for a roller of the present invention comprises: a plating tank 34 storing a trivalent chromium plating solution; a clamping means 36 holding the two ends of the roller 12 to be processed in a rotatable and energized manner and accommodating them in the plating tank in a horizontal direction; and an insoluble electrode 38, which is energized in a predetermined manner to bring the insoluble electrode 38 close to the outer peripheral surface of the roller 12 to be processed at a predetermined interval, and performing trivalent chromium plating on the outer peripheral surface of the roller 12. The insoluble electrode 38 is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller 12 to be processed.

[0037] In Figure 3, the structure of the aforementioned surrounding insoluble electrode 38 includes: a lower surrounding insoluble electrode 42 surrounding the lower outer peripheral surface 40 of the roller being treated, which is housed in the aforementioned plating tank 34 in the horizontal direction; and an upper surrounding insoluble electrode 46 surrounding the upper outer peripheral surface 44 of the roller being treated, which is housed in the aforementioned plating tank 14 in the horizontal direction.

[0038] In the trivalent chromium plating apparatus 10B for drum, the aforementioned lower side surrounding insoluble electrode 42 is a cross-type electrode.

[0039] Furthermore, the aforementioned upper surrounding insoluble electrode 46 of the aforementioned surrounding insoluble electrode 38 is opened and closed to a state covering the upper part of the processed roller 12 and an open state by the rotational action of the arms 48a and 48b. In this way, it approaches the aforementioned outer peripheral surface according to the roller diameter of the aforementioned processed roller 12. Moreover, the arms 48a and 48b are driven by a drive source not shown.

[0040] In addition, the aforementioned lower surrounding insoluble electrode 42 (42a, 42b) of the aforementioned surrounding insoluble electrode 38 adjusts the position of the protrusion of the aforementioned comb-shaped portion of the aforementioned lower surrounding insoluble electrode 42b into the concave portion of the aforementioned lower surrounding insoluble electrode 42a by means of the rotational movement of the arms 50a, 50b, so as to approach the aforementioned outer peripheral surface in accordance with the roller diameter of the aforementioned processed roller 12.

[0041] By adopting the aforementioned structure, even when performing trivalent chromium plating using a trivalent chromium plating solution, there is no problem of unprecipitated portions forming on a part of the processed roller 12, resulting in a roller with good, neat, and uniform precipitation and excellent brush resistance. Due to its excellent brush resistance, it can be used as a gravure roller. In addition, compared to the roller plating apparatus shown in Patent Document 2, which has an electrode only on the lower side, the trivalent chromium plating apparatus 10B for rollers also has the effect of reducing voltage by approximately 50%.

[0042] Next, in Figures 5 and 6, the third embodiment of the trivalent chromium plating apparatus for rollers of the present invention is shown, showing the trivalent chromium plating apparatus 10C for rollers.

[0043] The trivalent chromium plating apparatus 10C for a roller of the present invention comprises: a plating tank 54 for storing trivalent chromium plating solution; a clamping means 56 for holding the two ends of the roller 12 to be processed in a rotatable and energized manner and accommodating it in the plating tank in a horizontal direction; and an insoluble electrode 58 for being energized in a predetermined manner so that the insoluble electrode 58 approaches the outer peripheral surface of the roller 12 to be processed at a predetermined interval, and for performing trivalent chromium plating on the outer peripheral surface of the roller 12. The insoluble electrode 58 is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller 12 to be processed.

[0044] In FIG5, the structure of the aforementioned surrounding insoluble electrode 58 includes: a left surrounding insoluble electrode 62 surrounding the left outer peripheral surface 60 of the roller being treated, the roller being treated being housed in the aforementioned plating tank 54 in the horizontal direction; and a right surrounding insoluble electrode 66 surrounding the right outer peripheral surface 64 of the roller being treated being housed in the aforementioned plating tank 14 in the horizontal direction.

[0045] In the trivalent chromium plating apparatus 10C for drum, the aforementioned left-side surrounding insoluble electrode 62 and the aforementioned right-side surrounding insoluble electrode 66 are configured as cross-type electrodes.

[0046] Furthermore, the aforementioned left-side and right-side surrounding insoluble electrodes 62 and 66 of the aforementioned surrounding insoluble electrode 58 are opened and closed to cover the periphery of the processed roller 12 and to be open, respectively, by widening or narrowing the gap between the arms 68a and 68b. Thus, by adjusting the position of the protrusion of the comb-like portion of the right-side surrounding insoluble electrode 66 into the recess of the comb-like portion of the left-side surrounding insoluble electrode 62, the electrodes approach the outer peripheral surface according to the roller diameter of the processed roller 12. Furthermore, the arms 68a and 68b are driven by a drive source not shown.

[0047] By adopting the aforementioned structure, even when performing trivalent chromium plating using a trivalent chromium plating solution, there is no problem of unprecipitated portions forming on a part of the processed roller 12, resulting in a roller with good, neat, and uniform precipitation and excellent brush resistance. Due to its excellent brush resistance, it can be used as a gravure roller. In addition, compared to the roller plating apparatus shown in Patent Document 2, which has an electrode only on the lower side, the trivalent chromium plating apparatus 10C for rollers also has the effect of reducing voltage by approximately 50%.

[0048] Next, in Figures 7 to 10, the fourth aspect of the trivalent chromium plating apparatus for rollers of the present invention is shown, showing the trivalent chromium plating apparatus 10D for rollers.

[0049] The trivalent chromium plating apparatus 10D for a roller of the present invention comprises: a plating tank 74 for storing trivalent chromium plating solution; a clamping means 76 for holding the two ends of the roller 12 to be processed in a rotatable and energized manner and accommodating them in the plating tank in a horizontal direction; and an insoluble electrode 78 for being energized in a predetermined manner so that the insoluble electrode 78 approaches the outer peripheral surface of the roller 12 to be processed at a predetermined interval, and for performing trivalent chromium plating on the outer peripheral surface of the roller 12. The insoluble electrode 78 is a surround-type insoluble electrode surrounding the outer peripheral surface of the roller 12 to be processed.

[0050] In Figure 7, the structure of the aforementioned surrounding insoluble electrode 78 includes: a lower surrounding insoluble electrode 82 surrounding the lower outer peripheral surface 80 of the roller being treated, which is housed in the aforementioned plating tank 74 in the horizontal direction; and an upper surrounding insoluble electrode 86 surrounding the upper outer peripheral surface 84 of the roller being treated, which is housed in the aforementioned plating tank 74 in the horizontal direction.

[0051] In the trivalent chromium plating apparatus 10D for drum, the aforementioned lower surrounding insoluble electrode 82 and the aforementioned upper surrounding insoluble electrode 86 are respectively cross-type electrodes.

[0052] The aforementioned surrounding insoluble electrode 78, along with the lower surrounding insoluble electrode 82, is adjusted by the rotational movement of arms 90a and 90b to position the protrusion of the comb-shaped portion of the lower surrounding insoluble electrode 82b into the concave portion of the comb-shaped portion of the lower surrounding insoluble electrode 82a, so that the diameter of the processed roller 12 is close to the outer peripheral surface. Furthermore, arms 90a and 90b are driven by a drive source not shown.

[0053] Furthermore, the aforementioned surrounding insoluble electrode 78, along with the aforementioned upper surrounding insoluble electrode 86, adjusts the position of the protrusion of the comb-shaped portion of the other upper surrounding insoluble electrode 86b into the concave portion of the comb-shaped portion of the upper surrounding insoluble electrode 86a by the rotational movement of the arms 92a and 92b, so that the diameter of the processed roller 12 is close to the outer peripheral surface. Moreover, the arms 92a and 92b are driven by a drive source not shown.

[0054] By adopting the aforementioned structure, even when performing trivalent chromium plating using a trivalent chromium plating solution, there is no problem of unprecipitated portions forming on a part of the processed roller 12, resulting in a roller with good, neat, and uniform precipitation and excellent brush resistance. Due to its excellent brush resistance, it can be used as a gravure roller. In addition, compared to the roller plating apparatus shown in Patent Document 2, which has an electrode only on the lower side, the trivalent chromium plating apparatus 10D for rollers also has the effect of reducing voltage by approximately 50%.

[0055] The trivalent chromium plating method of the present invention uses the aforementioned trivalent chromium plating apparatus 10A-10D for rollers of the present invention to perform trivalent chromium plating treatment on the aforementioned roller 12 with a trivalent chromium plating solution. According to the trivalent chromium plating method of the present invention, even when trivalent chromium plating is performed using a trivalent chromium plating solution, there is no problem of unprecipitated portions forming on a part of the roller 12 being treated, and a roller with good, neat, uniform precipitation and excellent brush resistance can be obtained. Due to its excellent brush resistance, it can be used as a gravure roller.

[0056] The gravure cylinder manufacturing method of the present invention involves using the aforementioned trivalent chromium plating apparatus 10A-10D for cylinders of the present invention to perform plating treatment on the aforementioned roller to be processed with the aforementioned trivalent chromium plating solution, thereby manufacturing a gravure cylinder. According to the gravure cylinder manufacturing method of the present invention, even if trivalent chromium plating is performed using a trivalent chromium plating solution, there will be no problem of unprecipitated portions being generated in a part of the roller to be processed 12, and a gravure cylinder with good, neat, uniform precipitation and excellent brush resistance can be obtained. [Simplified Explanation of the Diagram]

[0019] [Fig. 1] is a left side view showing a first embodiment of the trivalent chromium plating apparatus for rollers according to the present invention. [Fig. 2(a)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the first embodiment, viewed from the left side. [Fig. 2(b)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the first embodiment, viewed from the right side. [Fig. 3] is a left side view showing a second embodiment of the trivalent chromium plating apparatus for rollers according to the present invention. [Fig. 4(a)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the second embodiment, viewed from the left side. [Fig. 4(b)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the second embodiment, viewed from the right side. [Fig. 5] is a left side view showing a third embodiment of the trivalent chromium plating apparatus for rollers according to the present invention. [Fig. 6(a)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the third embodiment, viewed from the left side. [Fig. 6(b)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the third embodiment, viewed from the right side. [Fig. 7] is a left side view showing the fourth embodiment of the trivalent chromium plating apparatus for rollers according to the present invention. [Fig. 8] is a perspective view of the trivalent chromium plating apparatus for rollers according to the fourth embodiment, viewed from the left side. [Fig. 9] is a plan view of the trivalent chromium plating apparatus for rollers according to the fourth embodiment, viewed from above. [Fig. 10(a)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the fourth embodiment, viewed from the left side. [Fig. 10(b)] is a perspective view of the main parts of the trivalent chromium plating apparatus for rollers according to the fourth embodiment, viewed from the right side. [Figure 11] is a photograph of a gravure cylinder produced by trivalent chromium plating using a trivalent chromium plating solution, using the plating apparatus for cylinders described in Patent Document 2.

Claims

1. A trivalent chromium plating apparatus for a roller, comprising: a plating tank storing a trivalent chromium plating solution; a clamping means for holding both ends of a roller to be processed in a rotatable and energized manner and accommodating it in the plating tank in a horizontal direction; and insoluble electrodes for being energized at predetermined intervals to bring the insoluble electrodes close to the outer peripheral surface of the roller to be processed, thereby performing trivalent chromium plating on the outer peripheral surface of the roller, wherein the insoluble electrodes are surround-type insoluble electrodes surrounding the outer peripheral surface of the roller to be processed, and the surround-type insoluble electrodes include: a lower surround-type insoluble electrode surrounding the lower outer peripheral surface of the roller to be processed, which is accommodating it in the plating tank in a horizontal direction; and / or an upper surround-type insoluble electrode surrounding the upper outer peripheral surface of the roller to be processed, which is accommodating it in the plating tank in a horizontal direction.

2. As in request item 1, the roller uses a trivalent chromium plating device, wherein, The aforementioned upper-surround insoluble electrode and / or the aforementioned lower-surround insoluble electrode are cross-type electrodes.

3. As in request item 1, a trivalent chromium plating apparatus for the roller, wherein, The aforementioned insoluble electrode is brought close to the outer circumferential surface by means of a cylinder or electric motor, depending on the diameter of the roller being processed.

4. As in request item 1, a trivalent chromium plating apparatus for the roller, wherein, The aforementioned surrounding insoluble electrode approaches the aforementioned outer peripheral surface by means of the rotational movement of the arm or the movement of widening or narrowing the interval, in accordance with the drum diameter of the aforementioned processed drum.

5. A method for trivalent chromium plating, comprising using a trivalent chromium plating apparatus for a roller as described in any one of claims 1 to 4, to plate the roller to be treated with the aforementioned trivalent chromium plating solution.

6. A method for manufacturing a gravure cylinder, comprising using a trivalent chromium plating apparatus for cylinders as described in any one of claims 1 to 4, to plate the aforementioned cylinder to be treated with the aforementioned trivalent chromium plating solution, thereby manufacturing a gravure cylinder.

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