Main body of a doctor blade chamber, doctor blade chamber and manufacturing method therefor

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the technical field of doctor blade chambers for rotary flexographic printing units and more particularly to the method of manufacturing such a doctor blade chamber and the main body of the doctor blade chamber.

[0002] Flexography is a rotary printing process that can be used on many media, such as foil or web, cardboard or plastic, and requires the use of flexible and raised printing plates, or printing forms.

[0003] In flexography, a printing unit comprises a plate cylinder, configured to carry the printing form, a screen cylinder or anilox cylinder, having on its surface a plurality of cells intended to collect ink in a quantity controlled by the volume of the cells, the screen cylinder being configured to transfer the ink onto the plate, a doctor blade chamber, configured to fill the cells of the screen cylinder, a pump, ensuring the conveyance of the ink from the ink reservoir to the doctor blade chamber, and a counter-pressure cylinder holding the support being printed against the plate cylinder.

[0004] In Figure 1 This structure of printing units is illustrated schematically. A printing machine comprises several printing units placed one after the other and each dedicated to a specific color.

[0005] In the present invention, flexography is understood to mean a rotary printing process which can be used on numerous media and which requires the use of relatively flexible and raised printing plates, or forms. STATE OF THE ART

[0006] Traditionally, a doctor blade chamber is made of metal, preferably aluminum, for manufacturing reasons, as metals can be transformed by extrusion.

[0007] However, a scraper chamber is an element that can reach several meters in length and which is, due to its volume and the material used to make it, heavy and difficult to handle and transport, particularly during maintenance: cleaning, replacement of a part or other.

[0008] WO 2005 / 090080 A1 describes a method and system for cleaning a doctor blade chamber, where a pressurized cleaning liquid is sprayed into the chamber by at least one cleaning nozzle.

[0009] To facilitate the design and lighten the doctor blade chamber, the latter are often designed in several parts, in particular the main body as described in document WO2016192735 A1. However, the production cost increases as the number of parts increases to produce this main body and the handling of the parts remains difficult, especially since at least one assembly operation is necessary. In addition, the bonding and assembly elements make the assembled part heavier, which increases the risks related to the non-resistance and fatigue of the assembled joints. In addition, the additional assembly / bonding operations reduce productivity in the process of producing the doctor blade chamber. Furthermore, these parts are often produced by liquid resin injection molding (RTM), which has the disadvantages of obtaining parts with variable section thickness and heterogeneous fiber compaction. SUBJECT OF THE INVENTION

[0010] The invention aims to remedy all or part of the aforementioned drawbacks.

[0011] The subject of the invention is a main body of doctor blade chambers, as defined in claim 1, comprising a first portion configured to hold a first doctor blade, a second portion configured to hold a second doctor blade, a third portion connecting the first portion and the second portion, a cavity intended to receive ink and delimited at least by the first portion, the second portion and the third portion, such that the main body is a single hollow closed profile extending along a main longitudinal axis XX, the main body being made of pultruded composite material.

[0012] Thanks to the configuration of the main body of the doctor blade chamber according to the invention, the doctor blade chamber is lighter, more robust and resistant due to the use of a pultruded composite material, and the configuration in a single profile avoids complex and time-consuming and therefore costly assembly / assembly operations. In addition, pultrusion makes it possible to obtain stable mechanical properties and a constant and uniform thickness at all points of the section and over the entire length of the profile. In addition, pultrusion makes it possible to have a part, in this case the main body, having a porosity rate of less than 2% and preferably less than 1%.

[0013] In the present invention, pultrusion means a process for the continuous manufacture of tubes and profiles made from composite materials.

[0014] The main body may in particular have a section of constant thickness. This characteristic is inherent to the pultrusion process used to produce the main body.

[0015] According to a characteristic of the invention, the pultruded composite material comprises thermoplastic fibers and / or aramid fibers and / or glass fibers and / or high modulus carbon fibers and / or high strength carbon fibers. Preferably, the pultruded composite material is a pultruded carbon composite material.

[0016] According to a characteristic of the invention, the composite material from which the main body is made comprises a volume of fiber strictly greater than 60% of the volume of the composite. Preferably, the volume of fiber is between 61% and 70% of the volume of the composite.

[0017] Thanks to this composition, the pultruded composite material has a specific modulus corresponding to a ratio between the longitudinal modulus of elasticity or Young's modulus of the composite and the density of the composite, much greater than the specific modulus of a pre-impregnated molded composite material, than that of a pultruded composite material comprising 60% or less fibers relative to the volume of the composite, and also than that of a composite material molded by low pressure resin injection.

[0018] Preferably, the pultruded composite material comprises between 61% and 70% of high-strength carbon fibers relative to the volume of the composite material. Table 1: Example of specific modulus results for a composite material with high strength carbon fibers as a function of its fiber volume in the material and the manufacturing process used. Methods used fiber volume in the composite (%) density (Kg / m3) Young's modulus (KN / m2) Specific module KNm / Kg performance ratio* Low pressure resin injection molding 50 1524 120 000 000 78740 100% Prepreg molding 56 1558 130 000 000 83440 106% Pultrusion ≤60% 1581 140 000 000 88552 112% Pultrusion 65 1605 149 000 000 92835 117% Pultrusion ≥70% 1632 160 000 000 98039 124% * compared to low pressure resin injection molding Table 2 example of specific modulus results for different materials used. : Materials used Process used fiber volume in the composite (%) density (Kg / m3) Young's modulus (KN / m2) Specific module KNm / Kg performance ratio* Composite material with high-strength carbon fibers Low pressure resin injection molding 50 1524 120 000 000 78740 100% Aluminum extrusion N / A 7850 205 000 000 26115 33% *compared to low-pressure resin injection molding of a composite material comprising 50% high-strength carbon fibers

[0019] As can be seen in the example illustrated in Table 1 above, the pultruded composite material comprising more than 60% fibers has a specific modulus much higher than the specific modulus of a pre-impregnated molded composite material, than that of a pultruded composite material comprising 60% or less fibers relative to the volume of the composite, and also than that of a composite material molded by low pressure resin injection.

[0020] According to a characteristic of the invention, the composite material in which the main body is produced by pultrusion with a fiber content strictly greater than 60%, has a performance ratio greater than 112% compared to the performance ratio of the same composite material in low pressure resin injection molding.

[0021] According to a characteristic of the invention, the main body comprises a non-woven textile integrated into the mass of the main body and arranged flush with the outer surface of the main body. The integration of a non-woven textile on the surface of the main body has the advantage of facilitating the cleaning of the doctor blade chamber in order to avoid mixing of an ink with residues of the color of the ink previously used. In addition, the non-woven textile makes it possible to reduce the surface tension of the fluids and to develop the qualities of the profile of the main body, particularly in machining and delamination.

[0022] Advantageously, the integration of the textile is carried out at the same time as the production of the main body of the doctor blade chamber.

[0023] According to a characteristic of the invention, the non-woven textile is a web with a thickness of between 0.05 mm and 1 mm.

[0024] According to a characteristic of the invention, the non-woven textile at least partially covers a portion of the surface of the main body. Preferably, the non-woven textile covers at least the surface of the first portion and / or the second portion and / or the third portion of the main body. Even more preferably, the non-woven textile covers the entire surface of the main body.

[0025] According to a characteristic of the invention, the non-woven textile is a textile comprising at least fibers, for example organic, inorganic, thermoplastic.

[0026] According to the invention, the doctor blade chamber comprises at least one pressurized water channel, arranged in the main body. The water channel has the function of serving to wash the doctor blade chamber and to remove residual inks.

[0027] According to the invention, the water channel extends over at least part of the length of the main body, preferably over the entire length of the main body. The water channel is housed in the hollow of the main body at the third portion.

[0028] According to the invention, the water channel comprises at least one washing nozzle opening into the cavity of the main body and extending projecting from the water channel through the third portion of the main body.

[0029] Preferably, the water channel comprises a plurality of washing nozzles. Advantageously, the plurality of washing nozzles are regularly spaced along the entire length of the water channel.

[0030] According to a characteristic of the invention, the third portion is set back relative to the first portion and the second portion of the main body, so that between the first portion and the second portion a cavity is formed.

[0031] According to a characteristic of the invention, the washing nozzles open into the cavity formed by the first, second and third portions of the main body.

[0032] According to a characteristic of the invention, the first scraper and the second scraper partially close the cavity formed by the first, second and third portions of the main body. The first scraper and the second scraper have the function of scraping the screened cylinder intended to come partially into the scraper chamber.

[0033] According to a characteristic of the invention, the main body comprises a first face intended to face the screen cylinder, and a second face opposite the first face.

[0034] According to a feature of the invention, the water channel is positioned in a hollow of the profile of the main body, a first side of the water channel being arranged against a first inner face of the main body and a second side of the water channel, opposite the first side of the water channel being arranged against a second inner face of the main body.

[0035] According to a feature of the invention, the water channel is glued to the main body. Advantageously, the water channel is glued with an expansive glue to provide a seal. The glue used to glue the water channel is, for example, a thermosetting glue.

[0036] According to a characteristic of the invention, the water channel is made of a composite material comprising, for example, carbon. According to a characteristic of the invention, the water channel is a profile.

[0037] According to a characteristic of the invention, the water channel has a substantially rectangular cross-section.

[0038] According to the invention, the doctor blade chamber further comprises an ink channel, separate from the water channel, extending at least partially along the main body, preferably along the entire length of the main body. The ink channel has the function of inking the printing unit by flexography.

[0039] The ink channel is arranged in the hollow of the profile of the main body. Advantageously, the ink channel has at least one ink outlet opening into the ink channel and extending projecting from the ink channel through the third portion of the main body.

[0040] According to one feature, the ink channel is made of a composite material comprising, for example, carbon. According to one feature of the invention, the ink channel is a profile.

[0041] According to one feature, the ink channel is of substantially circular cross-section.

[0042] According to one feature, the doctor blade chamber comprises a first end piece and a second end piece, each end piece being arranged at one end of the main body of the doctor blade chamber.

[0043] According to one feature, a portion of the first end piece is inserted into a first end of the profile of the main body.

[0044] According to one feature, a portion of the second end piece is inserted into a second end of the main body profile.

[0045] Advantageously, each end piece is inserted and then glued into the main body.

[0046] According to one feature, the first end piece has at least one orifice shaped to accommodate a pipe connecting the water channel to a water tank.

[0047] According to one feature, the first end piece has a second orifice shaped to accommodate a pipe connecting the ink channel to an ink reservoir.

[0048] The invention also relates to a method of manufacturing a main body of scraper chambers, the manufacturing method being characterized in that it comprises at least one step of pultrusion of a main body according to the invention.

[0049] The invention also relates to a method of manufacturing a scraper chamber according to the invention, the manufacturing method comprising at least one step of obtaining a main body according to the invention by pultrusion.

[0050] According to a characteristic of the invention, the manufacturing method comprises at least one additional step of insertion and assembly, preferably by gluing a water channel shaped to form a water network in the main body of the scraper chamber.

[0051] According to one feature, the water channel is preferably assembled glued in the cavity of the profile of the main body and particularly against the first face and the second face of the profile of the main body.

[0052] Advantageously, the glue used to bond the water channel is an expanding glue allowing the assembly to be sealed.

[0053] The manufacturing method may comprise a step of drilling at least one orifice in the main body and in the water channel, the drilling step allowing the subsequent positioning of washing nozzles.

[0054] The manufacturing method may further comprise a step of inserting an ink channel within the doctor blade chamber.

[0055] The manufacturing method may comprise a step of inserting and assembling, preferably by gluing, a first end piece at one end of the main body of the doctor blade chamber and a second end piece at the other end of the main body, while connecting the first end piece to the water channel and the ink channel. BRIEF DESCRIPTION OF THE FIGURES

[0056] The invention will be better understood from the following description, which relates to an embodiment according to the present invention, given by way of non-limiting example and explained with reference to the attached schematic figures, in which the identical reference numerals correspond to structurally and / or functionally identical or similar elements. The attached schematic figures are listed below: there Figure 1is a schematic illustration of a flexographic printing unit comprising a conventional doctor blade chamber, the Figure 2 is a perspective view of the scraper chamber according to the invention, the Figure 3 is a perspective view of the main body of the scraper chamber according to the invention and as illustrated in Figure 2 , there Figure 4 is a partial perspective view of the doctor blade chamber according to the invention and as illustrated in figures 2 And 3 , there Figure 5 is a detail view according to box A of the Figure 4 , there Figure 6 is a partial detail view of the scraper chamber according to the invention and as illustrated in figures 2 to 5 , there Figure 7 is a side view of the main body of the doctor blade chamber according to the invention. DETAILED DESCRIPTION OF THE FIGURES

[0057] As described above to illustrate the context of the invention, a printing group 100 comprises: a plate cylinder 104 configured to support a printing plate or form 108, a screen cylinder or anilox cylinder 103, having on its surface a plurality of cells intended to collect ink in a quantity controlled by the volume of the cells, the screen cylinder 103 being configured to transfer the ink onto the plate 10x, a doctor blade chamber 101, configured to fill the cells of the screen cylinder 103, a pump 102 ensuring the conveyance of the ink from the ink reservoir 107 to the doctor blade chamber 101, and a counter-pressure cylinder 105 holding the support being printed 106 against the plate cylinder 104, and thus against the plate 108.

[0058] The doctor blade chamber of the invention is designated by the reference numeral 1 and is illustrated in detail with reference to figures 2 to 7 .

[0059] The scraper chamber 1 according to the invention comprises a main body 2 made in a single piece which is a closed hollow profile, as illustrated in particular in Figure 3 . The main body 2 has a constant and uniform thickness at all points of the section and over the entire length of the profile, as illustrated in particular in figures 3 , 6 and 7 . The main body 2 extends along a longitudinal main axis XX as illustrated in particular in figures 2 And 3 . In addition, the main body 2 is made of pultruded composite carbon.

[0060] As visible in Figure 3 , the main body 2 has a first portion 2a, a second portion 2b and a third portion 2c. The third portion 2c connects the first portion 2a and the second portion 2b, the third portion 2c being shaped and intended to partially receive a screened cylinder within it. As can be seen in Figure 3, the third portion 2c is set back relative to the first portion 2a and the second portion 2b of the main body 2, so that between the first portion and the second portion a cavity 2e is formed.

[0061] Furthermore, the main body 2 has a first face 2.1 intended to face the screen cylinder and a second face 2.2 opposite the first face 2.1 as illustrated in Figure 3 .

[0062] According to the invention, the scraper chamber 1 further comprises a first scraper 3, the first scraper 3 being mounted on the first portion 2a of the main body 2 by means of a first scraper flange 5 as shown in figures 2 And 7 . Each flange is held by a fixing system 7 consisting of the cooperation of a screw or a pin, visible in Figure 2 with a 7a insert and visible at figures 4 And 7for example. In addition, the scraper chamber 1 comprises a second scraper 4, the second scraper 4 being mounted on the second portion 2b of the main body 2, opposite the first scraper 3, by means of a second scraper flange 6 as shown in figures 2 And 7 . In the example illustrated in figures 2 And 7 , the first scraper 3 and the second scraper 4 partially close the cavity 2e formed by the first 2a, second 2b and third 2c portions of the main body 2.

[0063] According to the invention, the main body 2 comprises a non-woven textile 16 arranged on the surface of the main body 2 as shown in a continuous line on the Figure 7 . In the example illustrated in Figure 7, the non-woven textile 16 is shown as covering the entire surface of the main body 2 but, in variants not shown, the non-woven textile could cover only a part of the main body 2, for example only the first face 2.1 or only the second face 2.2 or only one of the portions 2a, 2b, 2c of the main body 2.

[0064] According to the invention, and as represented in particular in Figure 7 , the scraper chamber 1 comprises a pressurized water channel 11, arranged in the main body 2 and more precisely in the hollow 2d of the profile of the main body 2 at the level of the third portion 2c. The water channel 11 advantageously extends over the entire length of the main body 2. Advantageously, the water channel 11 is a profile of substantially rectangular cross section.

[0065] As can be seen in Figure 7, a first side 2.3 part of the water channel 11 is arranged against the first inner face 2.1 of the main body 2 and a second side 2.4 of the water channel 11, opposite the first side of the water channel 11 is arranged against the second inner face 2.2 of the main body 2.

[0066] According to the invention, the water channel 11 comprises at least a plurality of washing nozzles 10 opening into the water channel 11 and extending projecting from the water channel 11 through the third portion 2c of the main body 2 as illustrated in figures 2 And 7 . In the example illustrated in Figure 7 , the water channel 11 is glued into the main body 2 by means of an expansive glue 17 allowing sealing. Advantageously, the washing nozzles 10 of the plurality are spaced regularly along the entire length of the water channel 11. As can be seen in Figure 7, the washing nozzles 10 open into the cavity 2e formed by the first, second and third portions 2a, 2b, 2c of the main body 2.

[0067] Furthermore, the doctor blade chamber 1 according to the invention comprises an ink channel 12, extending along the entire length of the main body 2 and arranged in the hollow 2d of the profile of the main body 2. The ink channel 12 comprises at least one ink outlet 13 illustrated in Figure 6 opening into the ink channel 12 and extending projecting from the ink channel 12 through the third portion 2c of the main body 2. Advantageously, the ink channel 12 is a profile of substantially circular cross-section.

[0068] According to the invention, the scraper chamber comprises a first end piece 8a and a second end piece 8b, each end piece 8a, 8b being arranged at one end of the main body 2 of the scraper chamber 1. As can be seen in particular in Figure 4, a portion of the first end piece 8a is inserted into a first end of the profile of the main body 2 and a portion of the second end piece 8b is inserted into a second end of the profile of the main body 2.

[0069] Advantageously, the first end piece 8a has at least one orifice shaped to house a pipe 9a connecting the water channel 11 to a water reservoir and a second orifice shaped to house a pipe 9b connecting the ink channel 12 to an ink reservoir as illustrated in figures 7 And 2 .

[0070] Furthermore, the doctor blade chamber 1 comprises a support 14 illustrated in the figures 2 to 5 And 7 arranged on the second face 2.2 of the main body 2 and configured to reinforce the doctor blade chamber 1. In addition, the doctor blade chamber 1 comprises a hook 15 intended to allow the doctor blade chamber system 1 to be attached.

[0071] Of course, the invention is not limited to the embodiment described and shown in the attached figures. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention as defined in the claims.

Claims

1. A main body (2) of a doctor blade chamber (1) comprising a first portion (2a) configured to hold a first doctor blade (3), a second portion (2b) configured to hold a second doctor blade (4) opposite the first doctor blade (3), a third portion (2c) connecting the first portion (2a) and the second portion (2b), a cavity (2e) intended to receive ink and delimited at least by the first portion (2a), the second portion (2b) and the third portion (2c), in which the main body (2) is a single hollow closed profile extending according to a longitudinal main axis (X-X), the main body (2) being made of a pultruded composite material, characterized in that the main body (2) comprises a pressurized water channel (11), said water channel (11) being positioned in a hollow (2d) of the profile of the main body (2) and extending along the main longitudinal axis (X-X), as well as an ink channel (12) separate from the water channel (11), said ink channel (12) being positioned in a hollow (2d) in the profile of the main body (2) and extending along the main longitudinal axis (X-X), and in that the water channel (11) comprises at least one washing nozzle (10) opening, on one side, into the water channel (11) and, on the other side, into the cavity (2e), and extending protruding from the water channel (11) through the third portion (2c) of the main body (2).

2. The main body according to claim 1, wherein the composite material is a pultruded composite carbon.

3. The main body according to any one of claims 1 or 2, wherein the composite material in which the main body is formed comprises a fiber volume strictly larger than 60% of the volume of the composite.

4. The main body according to claim 3, wherein the fiber volume is comprised between 61% and 70% of the volume of the composite.

5. The main body according to any one of claims 1 to 4, comprising a non-woven fabric (16) arranged on the surface of the main body (2), the non-woven fabric (16) being integrated into the mass of the main body (2).

6. The main body according to any one of claims 1 to 5, wherein the composite material in which the main body is made by pultrusion with a fiber rate strictly higher than 60%, has a performance ratio higher than 112% compared to the performance ratio of the same composite material in low-pressure resin injection molding.

7. A doctor blade chamber (1) comprising: - a main body (2) according to any one of claims 1 to 6, - a first doctor blade (3) mounted on a first portion (2a) of the main body (2), - a second doctor blade (4) mounted on a second portion (2b) of the main body (2), opposite the first doctor blade (3).

8. The doctor blade chamber according to claim 7, wherein a first side (2.3) of the water channel (11) being arranged against a first internal face (2.1) of the main body (2) and a second side (2.4) of the water channel (11), opposite to the first side (2.3) of the water channel (11) being arranged against a second internal face (2.2) of the main body (2).

9. The doctor blade chamber according to claim 7 or 8, wherein the water channel (11) is a profile made of a composite material comprising carbon.

10. A method for manufacturing a main body (2) of a doctor blade chamber (1), the manufacturing method being characterized in that it comprises at least one step of pultruding a main body according to any one of claims 1 to 6.

11. A method for manufacturing a doctor blade chamber according to any one of claims 7 to 9, the manufacturing method being characterized in that it comprises at least one step of obtaining a main body according to the manufacturing method according to claim 10.

12. The manufacturing method according to claim 11, comprising at least one additional step of inserting and assembling, preferably by gluing, a water channel (11) shaped to form a water network in the main body (2) of the doctor blade chamber (1).