JP2011063402A - Method of manufacturing conveyor belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a conveyor belt capable of preventing the generation of the warpage of the conveyor belt regardless of a belt structure. <P>SOLUTION: Taffeta 6A and 6B (restricting member) are integrally stuck to front/rear surfaces of an unvulcanized conveyor belt mold 4, and vulcanized by being pressure-heated by sandwiching the unvulcanized conveyor belt 4 by a pair of hot plates 2 and 3 in that state. After finishing vulcanization, the taffeta 6A and 6B are separated from a vulcanized conveyor belt mold 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a conveyor belt.

  In general, a conveyor belt is formed by laminating unvulcanized rubber sheets on both the front and back sides of a core layer made of canvas or steel cord to form an unvulcanized conveyor belt molded body. The part is charged into the vulcanizer's hot platen, pressed for a certain period of time and vulcanized by applying heat and pressure, and then the formed conveyor belt is removed from the vulcanizer and removed from the vulcanizer. By inserting the other part of the vulcanized conveyor belt molded body into a vulcanizer, charging it into a hot platen, and repeating the vulcanization process, the unvulcanized conveyor belt molded body is partially vulcanized in order. The belt molded body is vulcanized and molded, and both side edges are cut so as to have a predetermined width and connected endlessly to manufacture a conveyor belt. The unvulcanized belt molded body has a laminated structure of a front cover rubber layer, a core layer (for example, a canvas layer, a steel cord layer) and a back cover rubber layer, and a side cover rubber layer is provided as necessary. It has been.

  In the manufacturing process of such a conveyor belt, it has been confirmed that a so-called warp occurs in the belt due to a difference in thickness and a material difference between the front cover rubber layer and the back cover rubber layer. That is, for example, as shown in FIG. 5, in the conveyor belt 101, the thickness of the front cover rubber layer 103 provided on the upper side of the core layer 102 is 5 mm, and the thickness of the back cover rubber layer 104 is 1.5 mm. In this case, a difference in thermal shrinkage occurs due to the difference in thickness between the front and back cover rubber layers 103 and 104, and warps the thick side (in this case, the front cover rubber layer side) (see the arrow in FIG. 5). Also, even if the front and back cover rubber layers have the same thickness, if the rubber types of the front and back cover rubber layers are different and there is a large difference in heat shrinkage between them, the front side and the back side Warpage occurs due to the heat shrinkage difference. In FIG. 5, reference numerals 105 and 106 denote side cover rubber layers.

  When such warpage occurs in the conveyor belt, when cooling after completion of vulcanization, cooling with water, the cooling water collects in the recess formed by the warpage, and the cooling water accumulates. The cooling efficiency is different between the portion and the other portions, and it becomes difficult to ensure the belt performance uniformly throughout.

  In addition, as one of such warpages, for example, when a so-called ear warp is formed at the side edge portion of the conveyor belt, when the belt is provided on the belt conveyor, the conveyor belt is lifted from the return roller on the return side, thereby stabilizing the running. Sex is inhibited. That is, the belt may meander. Further, when detecting the presence or absence of a transported object using a photoelectric tube in the belt conveyor, if there is such an ear warp, the warp portion may block the photoelectric tube and cause a malfunction. Furthermore, in the case of a flat type belt conveyor that slides and loads a load from the side, if such an ear warp is formed on the conveyor belt, it is slid and loaded from the same height side. The transported material hits the warp portion, and the transported product cannot be smoothly loaded on the conveyor belt.

  Therefore, in order to prevent such warping including ear warping, the conveyor belt has an upper cover rubber layer above the reinforcing layer and an intermediate rubber layer between the reinforcing layer and the lower cover rubber layer. In Japanese Patent Application Laid-Open No. H10-260260, it is proposed that the intermediate rubber layer is formed of rubber having a larger shrinkage rate than the upper cover rubber layer (see, for example, Patent Document 1).

JP 2009-29556 A

  However, in the thing of patent document 1, it is a premise that it is a conveyor belt which has an upper surface cover rubber layer above a reinforcement layer, and has an intermediate rubber layer between a reinforcement layer and a lower surface cover rubber layer. Yes, it cannot be applied to conveyor belts that are not of such structure. That is, it cannot be applied to a conveyor belt that does not have such an intermediate rubber layer between the reinforcing layer and the lower cover rubber layer.

  An object of this invention is to provide the manufacturing method of the conveyor belt which can prevent generation | occurrence | production of the curvature of a conveyor belt irrespective of a belt structure.

  According to the first aspect of the present invention, an unvulcanized conveyor belt molded body is vulcanized by pressurizing it with a set of hot plates to form a conveyor belt in which a core layer is sandwiched between front and back cover rubber layers. A method of manufacturing a conveyor belt, wherein the front and back surfaces of the unvulcanized conveyor belt molded body have heat resistance and are integrated with the front and back surfaces of the unvulcanized conveyor belt molded body to restrain the front and back surfaces. A step of affixing a member, a step of vulcanization in a state in which the restraining members are adhered to the front and back surfaces of the unvulcanized conveyor belt molded body, and after the vulcanization, the front and back surfaces of the vulcanized conveyor belt molded body And a step of peeling each of the restraining members. Here, the “heat resistance” is heat resistance that can withstand a vulcanization step (vulcanization temperature, vulcanization time, etc.). “Integrating the front and back surfaces of the vulcanized conveyor belt molded body to restrain the front and back surfaces” means that the rubber is integrated with the rubber to suppress thermal deformation such as heat shrinkage of the rubber. However, this can be realized if the restraining member has a property that the coefficient of thermal expansion is smaller than that of rubber forming the front and back surfaces of the conveyor belt molded body.

  In this way, after vulcanization, the vulcanized conveyor belt molded body tends to warp due to the thermal shrinkage difference between the front and back surfaces of the belt as the temperature decreases. Since they are integrated, the belt front surface side and the back surface side are restrained by the restraining member, and warpage of the conveyor belt molded body after vulcanization is suppressed. Therefore, regardless of the thickness of the front and back cover rubber layers and their rubber types, the occurrence of warpage can be suppressed by attaching and constraining the restraining member to the belt front and back surfaces.

  The restraint member is further air permeable, has a uniform surface property on the side to be bonded to the unvulcanized conveyor belt molded body, and the vulcanized conveyor. It is desirable that the belt molded body is easily peelable from the front and back surfaces. Here, “easy to peel” means that an operator can peel off a vulcanized conveyor belt molded body manually without using a special tool such as a jig, even if the worker is not an expert. means.

  In this way, the restraining member is affixed to the front and back surfaces of the belt at the time of vulcanization, so that the restraining member functions to release air between the hot platen at the time of vulcanization and the conveyor belt molded body. In addition, since the restraining member is peeled after vulcanization, the surface properties can be made uniform and the appearance can be improved.

  According to a third aspect of the present invention, it is desirable that the step of peeling off the restraining member is peeled off after a vulcanization and a cooling period until cooling to a predetermined temperature.

  In this way, in order to suppress the warp, it is desirable to peel off after the belt surface temperature is reduced as much as possible, but it is desirable to peel off as soon as possible from the point of production efficiency, so by adjusting the cooling period, Both of these can be achieved.

According to a fourth aspect of the present invention, in the step of peeling the restraining member, after vulcanization, the belt surface temperature is cooled to a predetermined temperature or less by using a forced cooling means, and the vulcanization and the forced cooling are performed. It is desirable that the cooling by the means is synchronized. Here, the forced cooling means means air-cooled or water-cooled cooling means such as a fan or cooling water. “Synchronized” means that the time required for vulcanizing the conveyor belt molded body and the belt surface temperature of the conveyor belt molded body vulcanized by the strong cooling means after the vulcanization is below a predetermined temperature. This means that the time required for cooling is almost equal.
In this way, the forced cooling means is used to synchronize the vulcanization and the cooling by the forced cooling means, and the time required for vulcanization and the belt surface temperature is cooled to a predetermined temperature or less by the strong cooling means. Since the time required for the process is almost equal, the waiting time is reduced, and the production can be performed efficiently.

  As described in claim 5, the constraining member is a woven fabric or knitted fabric made of any one of natural fibers, chemical fibers, and metal fibers, or a woven fabric or knitted fabric using a mixture of these fibers, and reduces surface irregularities. It is desirable that surface processing is performed. Here, “surface treatment to reduce surface irregularities” means (i) crushing treatment such as calendering or pressing, (ii) dipping or coating, and the surface of the restraint member is made of silicon resin (polyethylene oxide). (Siloxane), urethane resin, acrylic resin, PVA (laundry paste) and the like are coated alone or in combination. The processes (i) and (ii) may be combined. This is because all the treatments facilitate the peeling by reducing the unevenness of the woven structure.

  In this way, the restraint member is subjected to surface processing to reduce surface irregularities, so that adhesion due to the anchor effect is prevented, and the restraint member can be easily peeled off after cooling.

  As described in claim 6, the front and back cover rubber layers are of the same rubber type, and the thickness of one rubber layer of the front and back cover rubber layers is at least 2.5 times the thickness of the other rubber layer. This is particularly effective.

  As described above, the present invention has heat resistance on the front and back surfaces of the unvulcanized conveyor belt molded body and is integrated with the front and back surfaces of the unvulcanized conveyor belt molded body to suppress thermal shrinkage of the front and back surfaces. A restraining member that exhibits the function to perform is attached and integrated, vulcanized, and peeled after vulcanization, so that the front and back surfaces of the conveyor belt molded body can be restrained by the restraining member attached to them. It is possible to suppress warping of the conveyor belt molded body after vulcanization.

It is a conceptual diagram which shows the vulcanization | cure process in the manufacture process of the conveyor belt which concerns on this invention. It is width direction sectional drawing of the conveyor belt which concerns on this invention. It is a figure which shows the relationship between curvature amount and rubber | gum thickness. It is a figure which shows the relationship between the belt surface temperature at the time of taffeta peeling, and the amount of residual warpage. It is explanatory drawing of the curvature of a conveyor belt.

  Hereinafter, the manufacturing method of a conveyor belt is demonstrated along drawing, focusing on the vulcanization | cure process which vulcanizes the unvulcanized conveyor belt molded object which is the feature point of this invention, and forms a conveyor belt.

  As shown in FIG. 1, a vulcanizer 1 used in a vulcanization process includes a pair of upper and lower heating plates (molds) 2 and 3, and forms an unvulcanized conveyor belt between the upper and lower heating plates 2 and 3. The body 4 is charged and pressed, and heat and pressure are applied for a predetermined time to vulcanize, thereby forming a vulcanized conveyor belt 5 having a desired width and thickness. As vulcanization conditions (vulcanization temperature, vulcanization pressure, vulcanization time, etc.), well-known conditions are adopted, but they are appropriately changed according to the unvulcanized conveyor belt molded body. In addition, the unvulcanized conveyor belt molded body 4 is a portion inserted into the vulcanizer 1 from the left side in FIG.

Prior to being inserted into the vulcanizer 1, the unvulcanized conveyor belt molded body 4 is provided with restraining members (taffeta 6A, in this embodiment) on each surface corresponding to the front and back surfaces of the belt (the surface of the conveyor belt). 6B) is affixed. The restraining member has heat resistance and is integrated with the front and back surfaces of the unvulcanized conveyor belt molded body 4 to restrain the front and back surfaces. By this restraint, the unvulcanized conveyor belt molded body 4 and the vulcanized body are vulcanized. The function of suppressing heat shrinkage of the conveyor belt molded body 5 is exhibited. Therefore, it is desirable to peel from the front and back surfaces of the vulcanized conveyor belt molded body 5 in a state where this heat shrinkage is eliminated.
Further, the restraining member has air permeability, has a uniform surface property on the side to be bonded to the unvulcanized conveyor belt molded body 4, and the vulcanized conveyor belt molded body 5 is peeled from the front and back surfaces. It should be easy. Examples of such restraining members include woven fabrics or knitted fabrics made of natural fibers, chemical fibers, or metal fibers, or mixed fabrics or knitted fabrics. In the embodiment, the taffeta 6A, 6B is employed as a restraining member, and surface processing is performed to reduce surface irregularities so that peeling is easy. Here, naturally, the natural fiber, the chemical fiber, and the metal fiber used as the material of the woven fabric or the knitted fabric have heat resistance with respect to the vulcanization temperature. For example, cotton, hemp, rayon as natural fibers, nylon, polyester, polypropylene, aramid, vinylon as chemical fibers, and stainless steel, steel, titanium, and aluminum as metal fibers. In the case of the woven fabric, monofilaments and multifilaments made of these fibers can be produced by weaving with a weaving method such as plain weave, twill weave, satin weave or the like. One of the woven or knitted fabrics is taffeta. Taffeta uses (i) warp yarns and main yarns, and weft yarns with a dense and dense plain woven fabric, or (ii) no or sweeter chemical fiber filament yarns. This refers to a slightly dense plain fabric with a high density (JIS L 0206: 1999 term number 1253).

  The unvulcanized conveyor belt molded body 4 with the taffeta 6A and 6B attached thereto is inserted into the vulcanizer 1 and charged between the upper and lower heating plates 2 and 3. At this time, since the unvulcanized conveyor belt molded body 4 does not stick to the heating plates 2 and 3 of the vulcanizer 1 by the taffeta 6A and 6B, the operation is easy and the positioning and the like can be adjusted easily.

  After charging, pressing is performed for a certain period of time, and vulcanization is performed by applying heat and pressure to the unvulcanized conveyor belt molded body 4. During vulcanization, the air existing between the unvulcanized conveyor belt molded body 4 and the hot plates 2 and 3 and the gas generated during vulcanization are discharged through the taffeta 6A and 6B, so that the vulcanized product is formed. The conveyor belt 5 is less prone to defects due to air holes (craters).

  After the vulcanization is completed, the formed vulcanized conveyor belt 5 is demolded, sent in the opposite direction to the direction in which the unvulcanized conveyor belt molded body 4 is inserted, taken out from the vulcanizer 1, and the subsequent unvulcanized The sulfur conveyor belt molded body 4 is inserted into the vulcanizer 1 with the taffeta 6A and 6B attached, and charged between the hot plates 2 and 3. When the formed vulcanized conveyor belt 5 is demolded, it can be easily removed from the hot plates 2 and 3 due to the template of the taffeta 6A and 6B. On the other hand, when the next uncured conveyor belt molded body 4 is charged, sufficient heat and pressure are applied to the unvulcanized conveyor belt molded body 4 at the longitudinal ends of the hot plates 2 and 3. Therefore, in order to re-vulcanize this portion, the portion incompletely vulcanized is placed in the hot plates 2 and 3.

  The conveyor belt 5 removed from the vulcanizer 1 after demolding is peeled off while winding the taffeta 6A, 6B on the front and back surfaces with the winding rolls 7A, 7B of the winding device 7 after a certain cooling time has passed. Winding around the take-up drum 8 sequentially. Here, in order to ensure the said fixed cooling period, the space | interval of the vulcanizer 1 and the winding device 7 is adjusted. In this case, if forced cooling is performed using a forced cooling means such as an electric fan or cooling water after vulcanization, the interval between the vulcanizer 1 and the winding device 7 can be shortened, which is advantageous for downsizing. It becomes. In particular, while the vulcanized molded body is being cooled by the forced cooling means, the next portion following the vulcanized molded body is vulcanized so that the vulcanization of the subsequent portion is performed. If the surface temperature of the vulcanized molded body is lowered to a predetermined temperature when the process is finished, the vulcanization by the vulcanizer 1 and the forced cooling by the forced cooling means are synchronized. The standby time for stopping the vulcanizer 1 can be reduced and production can be performed efficiently.

  In this way, the unvulcanized conveyor belt molded body 4 is partially and partially vulcanized sequentially, and finally the vulcanized conveyor belt 5 is manufactured.

  As is well known, the unvulcanized conveyor belt molded body 4 is molded as follows.

  The belt-like canvas wound in a roll shape is pulled out from the end sequentially, and then the adhesive rubber is applied or infiltrated or subjected to RFL (resorcin / formalin / latex) treatment, and then rolled again in a roll shape. Then, while pulling out the canvas that has been subjected to the treatment for improving the adhesiveness from the roll, an unvulcanized rubber sheet is laminated on each of the front and back surfaces of the canvas and unvulcanized ear rubber materials are attached to both ends in the width direction. The unvulcanized conveyor belt molded body 4 having a predetermined width and thickness is obtained by cutting excess portions of both ears. The unvulcanized conveyor belt molded body 4 formed in this manner is sequentially wound around a winding drum of a winding device.

  As shown in FIG. 2, the unvulcanized conveyor belt molded body 4 includes a core layer 11 having one or more canvases 11 a extending along the belt longitudinal direction, and a rubber type laminated on the front and back surfaces of the core layer 11. Are made up of front and back cover rubber layers 12 and 13 and side cover rubber layers 14 and 15. Taffeta 6A and 6B are affixed on the front and back cover rubber layers 12 and 13 of the unvulcanized conveyor belt molded body 4. Usually, the thickness of the front and back cover rubber layers 12 and 13 is larger than that of the back cover rubber layer 13.

  Here, as the canvas 11a of the core layer 11, polyester fiber, nylon fiber, aramid fiber, cellulose fiber, cotton fiber, a canvas in which these are mixed, and the like are used. The rubber materials for the cover rubber layers 12 and 13 include natural rubber, BR (polybutadiene rubber), SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), EPDM (ethylene-propylene-diene rubber). Or a mixture of these materials. In particular, a material having a small loss factor of viscoelastic properties and a small coefficient of friction is preferable because it can reduce the running resistance when overcoming the carrier roller of the belt conveyor. The cover rubber layers 12 and 13 may be provided with a reinforcing layer having a reinforcing canvas in order to increase the belt rigidity or prevent the occurrence of cracks.

Then, the test done about the conveyor belt 5 manufactured with the said manufacturing method and its result are demonstrated. Here, the test conditions for the conveyor belt (test body) are: belt size: width 600 mm × length 300 mm, surface pressure: 25 kgf / cm ² , rubber type: JIS-S cover rubber conformity, canvas type: EP-100 × 2 plies, restraining member: Taffeta T6000HS (Izumi Co., Ltd.).
(Relationship between thickness ratio of front and back cover rubber layer and amount of warpage)
When the taffeta is not provided, the taffeta is provided on both front and back surfaces, the taffeta is provided on the side with the thick rubber thickness, and the taffeta is provided on the side with the thin rubber thickness, a test was conducted. As shown in the graph, it can be seen that the smaller the difference in thickness of the front and back cover rubber layers, the smaller the amount of warpage, which is greatly affected by the difference in thickness of the rubber layer. At the same time, the effect of suppressing warping is recognized by providing a taffeta, and it can be seen that when taffeta is provided on both the front and back surfaces, the effect of suppressing warpage is the greatest.
(Relationship between belt surface temperature and warpage when taffeta is peeled off)
The ratio of the thickness of the front cover rubber layer and the back cover rubber layer is 4 of 5.0: 1.5, 5.0: 2.0, 5.0: 3.0, 5.0: 6.0. When the type was tested, as shown in FIG. 4, it can be seen that when the belt surface temperature is lowered, the remaining warp amount is smaller when the belt surface is peeled off, and the warpage suppressing effect is greater. The greater the difference in the thickness of the rubber layer, the more remarkable the effect. When the ratio of the thickness of the rubber layer is 5.0: 1.5, 5.0: 2.0, that is, It can be seen that the warpage suppressing effect is particularly remarkable when the thickness is 2.5 times or more the thickness of the other rubber layer. On the other hand, it can be seen that by providing the taffeta, even if the difference in thickness of the rubber layer is small, the warp suppressing effect is not impaired.

  Therefore, regardless of the thickness of the front and back cover rubber layers and the rubber type of the front and back cover rubber layers, the belt surface temperature is about 60 ° C. (preferably 50 ° C.) It can be said that the occurrence of warpage can be suppressed if the film is peeled after being lowered to a degree, more preferably about 40 ° C.).

  As in the conveyor belt manufacturing method described above, vulcanized by vulcanizing with the vulcanizer 1 with the taffeta 6A, 6B attached to the front and back surfaces of the unvulcanized conveyor belt molded body 4 It is possible to suppress warping from being caused by a difference in thermal shrinkage between the front and back surfaces of the conveyor belt molded body 5.

  In addition to that, the taffeta 6A and 6B have releasability and are interposed between the unvulcanized conveyor belt molded body 4 and the heating plates 2 and 3 of the vulcanizer, respectively. This eliminates the need for talc and other mold powders and silicon and other molds, and does not spoil the dust and molds, thereby deteriorating the work environment at the manufacturing site. Surface contamination can be avoided. Thus, it has been conventionally necessary to perform hot plate cleaning, which takes 5 to 10 hours per time, 3 to 4 times a month. However, since this is not necessary, significant efficiency improvement can be achieved. Even if dirt is present on the hot platen surface, the vulcanized conveyor belt molded body 5 is protected by the taffeta 6A and 6B, so that the dirt is not transferred to the belt front and back surfaces.

  The conveyor belt molded body 5 after vulcanization has a uniform surface in which the front and back surfaces are free from defects such as air holes (craters) and the surface properties such as patterns of the taffeta 6A and 6B are uniformly transferred. Therefore, the appearance is good and the appearance is excellent, and it is possible to suppress meandering during traveling and generation of abnormal noise when passing through pulleys, rollers, and the like. Furthermore, since the front and back surfaces are uniform, cracks due to bending deformation that occur when passing through pulleys or the like of a belt conveyor are less likely to occur.

  In the conveyor belt manufacturing method, the vulcanizer has a pair of upper and lower hot plates, but in order to increase productivity, another hot plate is added between the upper and lower hot plates to vulcanize in two stages. It can also be performed, and the taffeta 6A, 6B can be reused to reduce the manufacturing cost.

  In addition to the above embodiment, the present invention can be implemented with the following modifications.

(i) The restraining member having air permeability has a function of suppressing heat shrinkage of the front and back surfaces by constraining the front and back surfaces by being integrated with the front and back surfaces of the unvulcanized conveyor belt molded body while having heat resistance. Any material may be used as long as it exhibits, and in addition to the above-described woven fabric or knitted fabric such as taffeta, it is also possible to use satin , non-woven fabric, metal woven fabric, and the like.

  (ii) A conveyor belt without a side cover rubber layer is also possible.

  (iii) The core layer may have a steel cord instead of the canvas.

DESCRIPTION OF SYMBOLS 1 Vulcanizer 2 Hot plate 3 Hot plate 4 Unvulcanized conveyor belt molding 5 Vulcanized conveyor belt 6A, 6B Taffeta (restraint member)
11 Core layer 12 Front cover rubber layer 13 Back cover rubber layers 14 and 15 Side cover rubber layer

Claims (6)

This is a method for manufacturing a conveyor belt in which an unvulcanized conveyor belt molded body is vulcanized by pressurizing it with a set of hot plates to form a conveyor belt in which a core body layer is sandwiched between front and back cover rubber layers. And
A step of attaching a restraining member that constrains the front and back surfaces to each of the front and back surfaces of the unvulcanized conveyor belt molded body, which has heat resistance and is integrated with the front and back surfaces of the unvulcanized conveyor belt molded body;
Vulcanizing in a state where each of the restraining members is pasted on the front and back surfaces of the unvulcanized conveyor belt molded body,
After the vulcanization, the method further comprises a step of peeling the restraining members from the front and back surfaces of the vulcanized conveyor belt molded body.
The restraining member further has air permeability, has a uniform surface property on the side to be affixed to the unvulcanized conveyor belt molded body, and is peeled from the front and back surfaces of the vulcanized conveyor belt molded body The method for manufacturing a conveyor belt according to claim 1, wherein:
3. The method for manufacturing a conveyor belt according to claim 1, wherein the step of peeling the restraining member peels the restraining member after vulcanization, after the belt surface temperature is cooled to a predetermined temperature or lower.
In the step of peeling the restraining member, after vulcanization, the belt surface temperature is cooled to a predetermined temperature or less by using a forced cooling means, and the vulcanization and the cooling by the forced cooling means are synchronized. The method for manufacturing a conveyor belt according to claim 3.
The restraint member is a woven fabric or knitted fabric made of any of natural fibers, chemical fibers, and metal fibers, or a woven fabric or knitted fabric using a mixture of these fibers, and has been subjected to surface treatment to reduce surface irregularities. The manufacturing method of the conveyor belt as described in any one of Claims 1-4 characterized by these.
  The front and back cover rubber layers are of the same rubber type, and the thickness of one rubber layer of the front and back cover rubber layers is at least 2.5 times the thickness of the other rubber layer. The manufacturing method of the conveyor belt as described in any one of 1-5.

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