MXPA00006132A - Removable doctor blade holder - Google Patents

Abstract

A doctoring apparatus (10) for a roll (12) in a papermachine includes a doctor blade (14), a blade holder (16) for applying the doctor blade to the surface of the roll, and a doctor back (18) for supporting the blade holder. The blade holder is releasably secured to and removable from the doctor back for cleaning and repair outside of the papermachine.

Description

REMOVABLE SUPPORT FOR CUCH SCRAPER ILL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to scrapers used in papermaking machines, and relates in particular to the provision of a blade holder, which is easily detachable from the rear of the scraper and removable from the machine. to manufacture paper for cleaning, inspection and repair. 2. Description of the Prior Art The main components of a scraper system include the scraper blade, the blade holder, the rear part of the scraper and the loading mechanism. The scraper blade keeps the roller clean and / or the blade falls. It must be perfectly flat, straight and parallel, and its composition must be compatible with the roller with which it is in contact. The blade holder exerts a designated, uniform loading pressure on the blade. It keeps the blade firmly against the roller, adapts the irregularities of the roller and, within limits compensates the thermal expansion. The back of the blade is essentially the base structure of the blade. It serves as the supporting structure for the scraper blade. The loading mechanism pivots the back of the blade to load the scraper blade against the roller. The scraper blade holder designs used in recent years are very complex and have more components than the simplest blade supports used in the past. As a result, the most recent support designs require cleaning and more routine maintenance. The scraper blade mounts are usually mounted to the back of the blade rigidly with a series of fasteners. The maintenance and cleaning of the blade holder are presented while the scraper remains in the machine, but only in installations where the support is accessible. However, in many cases, the working structure of the machine for making paper or other equipment prevents access to the blade holder while it is in the paper making machine. In these cases, the entire structure of the scraper including the back of the scraper blade and the attached support must be removed from the paper machine for any cleaning or maintenance work. This task involves removing heavy equipment that requires extensive labor and machine time. After making the necessary repairs, all scraper assembly must be reinstalled in the paper machine, consuming more energy and valuable time. In addition to the reinstallation, the scraper must be realigned to the roller surface for optimum scraper performance. EP-A-0294992 discloses a previous design of a scraper apparatus typifying the aforementioned prior art.

COMPENDIUM OF THE INVENTION As is known from EP-A-0294992, the present invention relates to an apparatus for scraping or cutting a roller rotatably mounted on a paper machine to rotate about an axis extending in a direction transverse to the machine, said apparatus it comprises a scraper blade, a blade holder for applying said doctor blade to the surface of the roller, and a knife rear part for supporting the blade holder, the blade holder including: a support tray and support means for supporting the scraper blade on the support tray for pivotal movement about another axis parallel to the rotational axis of said roller. In contrast to EP-A-0294992 and in accordance with the invention, the support tray and the support means are components of an integral assembly provided with mounting means for removably mounting said integral assembly on the rear part of the scraper in a position operative adjacent to the roller and extending in the transverse direction of the machine; and with closing means to releasably secure the integral assembly in the operative position, said closing means being accessible and operable from one side of the paper machine. As is evident below, various embodiments of the invention are described, each of which avoids or at least significantly minimizes the aforementioned problems by providing a scraper blade holder, which is easily detachable from the back of the support blade. In this way, while the back of the blade remains unchanged in the paper machine, the operating personnel can remove the blade holder for cleaning and maintenance. Then, the blade holder is returned to its operative position on the back of the blade and locked in place.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, aspects and advantages of the present invention will be described in greater detail with reference to the accompanying drawings, in which: Figure 1 is a side view of a blade assembly according to the present invention, Figure 2 is an enlarged view of the scraper blade holder shown in Figure 1; Figure 3A is a sectional view taken along line 3A-3A of Figure 2 showing the blade holder in its operative position attached to the rear part of the blade; Figure 3B is a view similar to Figure 3A showing the blade holder removed from the rear of the blade; Figure 3C is a horizontal sectional view taken along the line 3C-3C of Figure 3A; Figure 4 is a view similar to Figure 2 showing an alternative embodiment of a blade holder according to the present invention; Figure 5 is a horizontal sectional view taken along line 5-5 of Figure 4; Figure 6 illustrates another embodiment of a blade holder according to the present invention; Figure 7 is a horizontal sectional view taken along line 7-7 of Figure 6; Figure 8 illustrates another embodiment of a blade holder according to the present invention; Figure 9 is a perspective view of one of the dovetail washers employed in the arrangement shown in Figure 8; Figure 10 illustrates yet another embodiment of a blade holder according to the present invention; Figure 11 is a perspective view of one of the stepped washers used in the arrangement shown in Figure 10; Figure 12 is a perspective view showing a further modification to the blade supports modeling the concepts of the present invention; and Figure 13 is a partial plan view of the blade holder and back of the blade on the side of the paper machine.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Referring initially to Figure 1, a blade assembly according to the present invention is generally illustrated adjacent to a paper machine roll 12. The roller 12 is driven through conventional means (not shown) to rotate around of an axis A, - extending in the transverse direction of the machine. The blade assembly includes a scraper blade 14, a blade holder 16, a knife rear part 18 and a loading mechanism 20. The blade rear part is mounted on the frame of the paper machine for pivotal movement around the blade. an axis A2 extending in the direction transverse to the machine parallel to the rotational axis] of the roller 12. The loading mechanism 20 includes a piston-cylinder unit 22 acting through a lever arm 24 for pivoting the rear part of the blade 18 about its axis A2 in order to load the scraper blade 14 against the surface of the roller 12. With further reference to Figures 2 and 3A-3C, it will be seen that the blade holder 16 includes a tray 26 with straight brackets 28 located between a discharge tube 30 and a loading tube 32. An upper pressure plate 34 covers the tubes 30, 32 and has dependent brackets 36, which are connected to the brackets 28 through of a rod 38 for pivotal movement about a third axis A3 parallel to the axes A, and A2.

Extremities 40 cooperate with the underside of the upper pressure plate 34 to retain the doctor blade 14 at its extended forward extension. The tubes 30, 32 are driven by means of fluid, the tube 32 serving to coact with the force that is applied by the loading mechanism 20 to apply the blade 14 to the surface of the roller 12. The tube 30 serves to discharge the blade of the roller surface, in addition to acting as a front seal. A pair of confronting mounting strips in the shape of L 42a, 42b is secured to the underside of the tray 26. The mounting strips have horizontal flanges 44a, 44b spaced apart from one another to define a continuous slot 46 communicating with an inner depression 47. A shelf 50 extends forwardly from and it forms an integral part of the rear blade part 18. Shoulder screws 52 are threaded on the shelf 50 at separate locations along the length of the slot 46. A closure strip 54 is interposed between the shoulders 44a, 44b and the heads of the shoulder screws 52. The closure strip is slotted as in 56 to adapt the shoulder screws, and the slots 56 are partially confined through elastic tabs 58, which are bent upwardly out of the plane of the closing strip. The closure strip 54 is slidable longitudinally with respect to the shelf 50 of the rear part of the blades and the mounting strips 42a, 42b on the underside of the tray 26.

When in the locked position as shown in Figures 3a and 3c, the tabs 58 are bent downwardly by the heads of the shoulder screws 52 toward the plane of the strip 54, thereby exerting a downward force that holds the shoulders 44a , 44b against the shelf 50, thus fixing the scraper blade holder 16 in its operative position on the rear part of the blade 18. As best seen in Figure 3a, a pin 60 or the like on one side of the paper machine is used to slideably secure the closure strip 54 in its locked position. When it is necessary to clean or maintain the blade holder, the pin 60 is removed and the closing strip 54 is moved to its unlocked position as shown in Figure 3b. This relieves the clamping force exerted by the elastic tabs 58, thus allowing the blade holder and scraper blade to be pulled out longitudinally as a unit outside the paper machine. After cleaning and maintenance, the blade holder is inserted longitudinally back into the paper machine, and the clamping strip returns to its locked position. An alternative embodiment of the invention is illustrated in Figures 4 and 5, wherein a mounting strip 62a is secured to the underside of the tray 26. A second mounting strip 62b is connected to the strip 62a through shoulder screws 64 extending through angled grooves 66 The strips 62a, 62b co-act to define a dovetail groove 68 for receiving a dovetail strip 70 secured to the ledge 50 of the rear part of the blade through the screw 72. The longitudinal movement of the strip 62b in the direction A will push it laterally against the dovetail strip 70, thus holding the blade holder in place. The longitudinal movement of the strip 62b in the opposite direction B will displace the strip 62b laterally away from the strip 70, thereby releasing the blade holder to remove the rear part of the blade. If the strip 62b is only slightly displaced laterally, the blade holder can be slid longitudinally in and out of its operative position, while a more pronounced lateral displacement of the strip will allow the blade holder to be raised and lowered onto the blade. back of blade. In the embodiment shown in Figures 6 and 7, a male dovetailed strip 74 is secured to the underside of the tray 26 and a female dovetail strip 76 is secured to the ledge 50 of the rear part of the dovetail. knife. A group of screws 78 on one side of the paper making machine serves to fix the male dovetail strip 74 against sliding movement relative to the dovetail thread 76. When the screw 78 is returned as shown in Figure 7m the blade holder is free to slide longitudinally in and out of its operative position on the rear part of the blade. In the embodiment shown in Figures 8 and 9, a female dovetail strip 80 is secured to the underside of the tray 26, and frustoconical dovetail washers 82 a and a are separated along the length of shelf 50 on the back of the blade. In Figures 10 and 11, staggered washers 84 are secured at separate locations along the underside of the tray 26, and a mounting strip 86 is secured to the shelf 50 on the back of the blade. The mounting strip 86 has a cutting channel 88 along which the stepped washers slide during longitudinal removal and insertion of the blade holder. Figure 12 illustrates another embodiment, wherein a mounting strip 90 with a cutting channel 92 is secured to the shelf 50 of the rear part of the blade. Channel 92 is interrupted at 94 at separate sites along its length. This allows the stepped washers 84 of Figures 11 or 12 and stepped strip segments 96, which are secured to the underside of the blade support tray 26 slide along the channel 92 to positions where they can exit through the interrupted sections 94 either laterally in the A direction or vertically in the B. In the embodiments shown in Figures 8 to 12, closure means of a certain type are provided on one side of the machine to prevent removal of the blade holder from the back of the blade during the operation of the machine for make paper As shown in Figure 13, the lock can be achieved by providing a bracket 98 on the tray 26 on one side of the paper making machine, which is detachably connected to the shelf 50 of the rear part of the knife through a pin 100 or similar. In view of the foregoing, it will now be appreciated by those skilled in the art that the present invention provides for easy separation of the scraper blade holder from the back of the blade for removal of the papermaking machine. The embodiments illustrated in Figures 1-5 provide means for securely holding the blade holder to the back of the blade during the operation of the paper making machine. Other embodiments as illustrated in Figures 6-13 lock the blade holder in its operative position, but do not exert additional clamping forces. All the arrangements are advantageous, since the blade holder removal capability provides maintenance personnel with the opportunity to clean and perform maintenance outside the paper making machine, without disturbing the back of the blade.

Claims (9)

1. - An apparatus (10) for scraping a roller (12) rotatably mounted on a papermaking machine to rotate about an axis (Ai) extending in a direction transverse to the machine, the apparatus comprising a scraper blade (14), a blade holder (16) for applying said doctor blade to the surface of the roller, and a knife back part (18) for supporting the blade holder, the blade holder including: a support tray (26) and supporting means (34, 40, 28, 36, 38) to support the scraper blade on the support tray for pivotal movement about another axis (A3) parallel to the rotational axis (Ai) of the roller; wherein said support tray and support means are components of an integral assembly provided with mounting means (42a, 42b, 52, 54; 62a, 62b, 70, 72; 80, 82; 84, 86; 90, 96 ) for the removable assembly of the integral assembly on the rear part of the blade (18) in an operative position adjacent to the roller and extending in the transverse direction of the machine; and with closure means (60; 78; 98, 100) to releasably secure the integral assembly in the operative position, the closure means being accessible and operable from one side of the paper making machine.

2. The apparatus according to claim 1, wherein the blade holder (16) is removable in and out of the operative position in the transverse direction of the machine.

3. - The apparatus according to claim 1, wherein the blade holder (16) is movable in and out of the operative position in a direction transverse to the transverse direction of the machine.

4. An apparatus according to claim 1, wherein the mounting means comprise mechanically interpenetrable components (42a, 42b, 54, 62a, 70, 76, 74, 80, 82, 86, 84), at least one of said components extending longitudinally in the transverse direction of the machine.

5. The apparatus according to claim 4, wherein the interengaging components (42a, 42b, 54, 62a, 70, 74, 76) each extend coextensively in the transverse direction of the machine.

6. The apparatus according to claim 5, wherein the inter-copying components include a slidable member (54).

7. The apparatus according to any of claims 1 to 6, wherein the closing means take the form of pins or screws (60, 78, 100).

8. The apparatus according to any of claims 1 to 7, wherein the support means includes a pressure plate (34) and ends (40), the scraper blade (14) disposed between the pressure plate (34). ) and limbs (40).

9. The apparatus according to claim 8, further comprising fluid-actuated loading means (30, 32) disposed in the support tray 26 on the opposite sides of the other axis (A3) to pivotally adjust the pressure plate for forcedly applying said scraper blade to the roller.