TWI655099B - Two-way scraper device for textile printing machine - Google Patents

Abstract

A two-way scraper device for textile printing machine. The two-way scraper device includes: a scraper assembly. The scraper assembly includes a knife holder, two scrapers and a corresponding scraper pressure plate. The knife holder has a groove, and the two scrapers are inclined in a manner opposite to each other Installed on both sides of the opening of the groove and extending in the longitudinal direction, the blade pressure plate is used to press the blade against the blade holder; the end sealing member is used to seal the two longitudinal ends of the blade assembly; the displacement mechanism is used to make the blade The assembly pivotally moves between the working position and the non-working position, the displacement mechanism has a pivoting member; the adjustment mechanism is used to adjust the contact pressure between the scraper and the roller when the scraper assembly is in the working position. The invention also provides a textile printing machine including a two-way scraper device.

Description

Bidirectional scraper device for textile printing machine

The invention relates to a two-way scraper device for textile printing machine. The invention also relates to a textile printing machine including the two-way scraper device.

There are many printing and dyeing processes and machinery categories, and a wide range of products. At present, the main printing processes are screen printing, roller printing, plate printing, transfer printing and digital inkjet printing. The corresponding equipment is mainly rotary screen printing machine, flat screen printing machine, roller printing machine, platen Printing machine, transfer printing machine, digital inkjet printing machine, etc.

The printing machine usually includes an inking or sizing device for inking or sizing the printing plate roller or the coating roller (or anilox roller). Traditional inking or sizing devices usually include rollers, doctor blades and liquid tanks. The lower semicircle of the roller is immersed in the liquid tank, and the ink or slurry in the liquid tank is applied to the surface of the roller as the roller rotates. The doctor blade is usually a single doctor blade, which is used to scrape off excess ink or slurry on the roller. Such an inking or sizing device may be called an open inking or sizing device, and the scraper used may be called an open single scraper.

The traditional inking or sizing device with an open single scraper has problems such as uneven scraping liquid, easy liquid accumulation between the scraper and roller, and residual liquid flow.

In addition, because the liquid tank is open, it also has the following defects: 1) The liquid in the liquid tank has a large amount of volatilization, and the air flow around the printing unit will be accelerated by the exhaust fan, so that the liquid is easily deposited and cannot be smoothly transferred Onto the printing material; 2) a large amount of liquid evaporates, If it is not replenished in time, it will change the viscosity of the liquid; 3) The liquid is easily affected by the ambient temperature, which makes the printing quality not stable enough.

Moreover, the prior art doctor blade device cannot finely adjust the contact pressure between the doctor blade and the roller. Therefore, on the one hand, the liquid supply quality may not be high due to too low contact pressure, and on the other hand, the surface of the roller may be worn due to excessive contact pressure.

In view of this, the present invention provides a new type of two-way scraper device for textile printing machines. The two-way scraper device can be used to solve the above technical problems.

The two-way scraper device for textile printing machine includes: a scraper assembly including a knife holder, two scrapers and a corresponding scraper pressing plate, the knife holder extends in the longitudinal direction, and the knife holder has a groove, concave on the side facing the roller The groove forms a space to accommodate the liquid to be supplied to the roller, and the two scrapers are obliquely installed on both sides in the lateral direction of the opening of the groove and extend in the longitudinal direction, and the scraper pressure plate is used to press the scraper against the knife holder Upper; end sealing parts, the end sealing parts are placed at the two longitudinal ends of the knife holder, used to seal the two longitudinal ends of the blade assembly; the shifting mechanism, the shifting mechanism has a pivoting member for making The doctor blade assembly pivotally moves between a working position and a non-operating position, wherein, in the working position, the doctor blade is pressed against the roller, and the two doctor blades of the doctor blade assembly and the roller surface and end seals between the two doctor blades are sealed The components together form a closed liquid holding cavity, in the non-working position, the scraper assembly is separated from the roller; and an adjustment mechanism for adjusting the scraper when the scraper assembly is in the working position The contact pressure between the rollers.

Preferably, the pivoting member of the displacement mechanism is provided at the lateral first end of the bidirectional doctor device, and the adjustment mechanism is provided at the lateral second end opposite to the lateral first end.

Preferably, the adjustment mechanism includes a nut screw mechanism and a fixed to the scraper assembly The adjustment part adjusts the contact pressure through the interaction between the nut screw mechanism and the adjustment part.

Preferably, the nut screw mechanism includes a nut component and an adjustment screw, the nut component is fixed to the mounting frame of the two-way scraper device, and one end of the adjustment screw presses against the adjustment portion, wherein, by screwing the adjustment screw relative to the nut component The adjustment parts interact to move the doctor blade assembly relative to the roller, thereby adjusting the contact pressure between the doctor blade and the roller.

Preferably, the adjustment screw is pressed against the adjustment portion in a direction that moves the blade assembly away from the roller.

Preferably, the two-way scraper device further includes a locking mechanism for locking the working position of the scraper assembly.

Preferably, the locking mechanism includes a locking nut, the locking nut is screw-coupled with the adjusting screw, and the working position of the scraper assembly is locked at the locking position.

Preferably, the two scrapers are a reverse scraper and a forward scraper, wherein the reverse scraper is used to scrape off excess liquid supplied to the roller, and the forward scraper is used to remove impurities on the roller and perform sealing.

Preferably, the pivoting member of the displacement mechanism is provided at the lateral first end of the two-way scraper device, the adjustment mechanism is provided at the lateral second end opposite to the lateral first end, and wherein the reverse blade approaches The lateral first end of the bidirectional scraper device is provided, and the forward scraper is disposed close to the lateral second end of the bidirectional scraper device.

Preferably, the blade contact angle of the reverse blade is between 120 ° and 160 °.

Preferably, the blade contact angle of the forward blade is between 20 ° and 60 °.

Preferably, the blade front edge has a bevel angle between 20-40 °.

Preferably, the roller is a printing plate roller, and the blade front edge is not tangent to the printing plate roller Faces are parallel.

Preferably, the roller is a coating roller or an anilox roller, and the blade front surface is parallel to the tangent surface of the coating roller or the anilox roller.

Preferably, the blade is made of stainless steel, and the thickness of the blade is generally between 0.15 mm and 0.20 mm.

Preferably, the end sealing member is installed in the groove of the knife holder in an interference fit manner.

Preferably, the end sealing member is composed of two clamping plates with a sealing material arranged between the two clamping plates.

Preferably, the sealing material is polyurethane rubber.

Preferably, the two-way scraper device further includes a constant temperature heating system for maintaining the temperature of the ink chamber between room temperature and 40 degrees Celsius.

The invention also provides a textile printing machine, the textile printing machine comprising a bidirectional scraper device according to the invention.

Compared with the existing scraper device, the bidirectional scraper device of the present invention has the following beneficial effects: Since the liquid containing chamber is completely closed, the volatilization of the water solvent when ink or slurry is used is avoided, and the color hue of long-term mass printing is stabilized. The foam problem accompanying the use process is terminated; in addition, the ink scraping or squeegee is uniform and clean, and there is no problem of residual liquid flowing; the liquid circulation in the liquid holding chamber is smoother and can adapt to the production of high speed conditions.

In addition, the adjustment mechanism of the bidirectional doctor blade device of the present invention can finely adjust the contact pressure between the doctor blade and the roller when the doctor blade assembly is in the working position, thereby accurately adjusting the contact pressure to the desired pressure range; at the same time, the adjustment Small number of mechanism parts and simple structure Single, which is convenient for the structural arrangement of the two-way scraper device and saves costs.

1‧‧‧Two-way scraper device

10‧‧‧Scraper assembly

11‧‧‧Knife holder

12‧‧‧Scraper

121‧‧‧Reverse scraper

122‧‧‧Front scraper

13‧‧‧Squeegee pressure plate

14‧‧‧groove

15‧‧‧End sealing parts

2‧‧‧End plate

20‧‧‧shifting mechanism

21‧‧‧bearing

22‧‧‧bearing sleeve

23‧‧‧Shaft end cover

24‧‧‧Smooth cover

3‧‧‧Clamping plate

30‧‧‧Regulation mechanism

31‧‧‧Adjusting screw

32‧‧‧Fixed board

4‧‧‧Sealing material

40‧‧‧Locking mechanism

41‧‧‧Lock nut

42‧‧‧handle lever

6‧‧‧Support plate

7‧‧‧Adjustment board

8‧‧‧First pile head (shaft)

9‧‧‧Second pile head (shaft)

A-A‧‧‧hatching

B-B‧‧‧hatching

[Fig. 1] A schematic front view showing a two-way doctor device for a textile printing machine according to an embodiment of the present invention.

[FIG. 2] A side sectional view taken along section line A-A in FIG. 1.

[Fig. 3] A side sectional view taken along section line B-B in Fig. 1 is shown.

The technical solutions of the present invention will be further described in detail below through the drawings and the listed embodiments. It should be noted that any technical features and any technical solutions in this embodiment do not limit the protection scope of the present invention, and the protection scope of the present invention should include any equivalent or alternative technology that can be thought of by those skilled in the art without paying any creative work. Program.

In this specification, referring to FIG. 1, the longitudinal direction refers to a direction extending along the axial direction of the printing plate roller, and the lateral direction refers to a direction perpendicular to the longitudinal direction and located in the plane of the paper where FIG. 1 is located, lateral The direction refers to a direction perpendicular to the longitudinal direction and the lateral direction. In addition, the upper end and the lower end are only used to indicate the relative position of each component in FIG. 1, and do not represent the position in the actual use process.

For the convenience of description, in the following embodiments, a bidirectional doctor device for printing plate rollers is used as an example for description, but it should be known that the bidirectional doctor device according to the present invention can be used for other rollers that require surface feeding, such as The coating roller (anilox roller) for sizing the fabric, or the humidifying roller for wetting the temporary transfer carrier, etc., will not be repeated here.

As shown in FIG. 1, according to an embodiment of the present invention, the bidirectional scraper of the present invention The device 1 includes a doctor blade assembly 10, a displacement mechanism 20, an adjustment mechanism 30, and a locking mechanism 40.

The blade assembly 10 includes a blade holder 11, two blades 12 and two blade pressing plates 13.

As shown in FIG. 1, the blade holder 11 extends in the longitudinal direction. The blade holder 21 has a groove 14 extending in the longitudinal direction on the side facing the printing plate roller for forming an accommodating space for accommodating ink. The opening of the groove 14 is rectangular, and is formed centrally on the knife holder 11.

The two scrapers 12 extend in the longitudinal direction and are respectively arranged on both sides of the opening of the groove 14 of the knife holder 11. Specifically, as shown in FIG. 2, the two blades 12 are arranged obliquely with the blade tips opposed so that the blade tips of the blades come into contact with the surface of the printing plate roller at a specific blade contact angle. Among them, the blade contact angle refers to the circumferential tangential speed direction of the printing plate roller at the point of contact between the blade and the printing plate roller and the blade extension line (which is perpendicular to the lengthwise extension direction of the blade and extends from the blade back to the blade tip Direction extending).

Referring to FIG. 3, according to the contact angle of the blade, the two blades 12 may be referred to as a reverse (or reverse) blade 121 and a forward blade 122 respectively. The function of the reverse blade 121 is to scrape off excess ink on the printing plate roller, thereby providing the supply ink required for printing, while the function of the forward blade 122 is mainly used to seal and remove residual ink and accumulated impurities.

The blade contact angle of the reverse blade 121 is greater than 90 °, so that the blade can shovel the ink on the printing plate roller, and the ink can apply pressure to the blade to make it close to the surface of the printing plate roller, scraping the ink The effect is better, and the wear of the doctor blade and the printing plate roller is reduced. In addition, since the reverse blade is at an obtuse angle with the printing plate roller, the ink between the blade and the plate roller will not accumulate, thereby making the ink circulation in the liquid containing chamber smoother.

In an embodiment of the present invention, the blade contact angle of the forward blade 122 is between 20 ° and 60 °. Preferably, the blade contact angle of the forward blade can be between 30 ° and 50 ° between. More preferably, the blade contact angle of the forward blade may be 45.

In the embodiment of the present invention, the blade contact angle of the reverse blade 121 is between 120 ° and 160 °. Preferably, the blade contact angle of the reverse blade can be between 130 ° and 150 °. More preferably, the blade contact angle of the reverse blade may be 135 °.

At the end where the doctor blade contacts the printing plate roller (that is, the end of the doctor blade edge), the doctor blade has a longitudinally extending end surface, that is, the blade blade front surface, which has a bevel angle between 20-40 °. When the doctor blade is applied to the printing plate roller, the blade front surface is not parallel to the tangent plane of the printing plate roller, which forms the effect of point scraping or line scraping to prevent the phenomenon of unclean scraping and the occurrence of wire scrapes. When the doctor blade is applied to the coating roller or anilox roller (that is, when applied to the coating or sizing function), the blade front edge is parallel to the tangent plane of the coating roller or anilox roller, thereby forming a surface scraping effect to make coating or coating The slurry is even. In this case, the width of the contact surface formed by the blade front surface of the doctor blade and the coating roller or anilox roller is generally 1-2 mm.

In addition, the scraper can be made of stainless steel. The thickness of the scraper is generally between 15 filaments and 20 filaments (0.15 mm to 0.20 mm).

The two scraper pressure plates 13 are respectively used to press the corresponding scraper 12 against the knife holder 11. In the embodiment of the present invention, the blade pressing plate 13 presses the blade 12 against the blade holder 11 with screws.

End seal members 15 are respectively installed at the two longitudinal ends of the knife holder 11. The end sealing member 15 is installed in the groove 14 of the blade holder 11 in an interference fit manner, and is used to seal the two longitudinal ends of the blade assembly. The end seal member 15 includes two clamping plates 3, and a sealing material 4 is fixed between the two clamping plates 3. The sealing material can be fixed between the two clamping plates by means of bolt connection.

Traditionally, the sealing material is a foam sealing material, such as foam plastic. The foam sealing materials are all fixed-width, which has the defects of short life. In the embodiment of the present invention, the sealing material 4 is polyurethane rubber, so that the sealing material 4 can be used repeatedly for a long time and the width of the sealing material 4 can be adjusted.

According to the above configuration, when the blade assembly is pressed against the printing plate roller, the surface of the printing plate roller between the two blades 12, the two blades 12, the groove 14 of the blade holder 11, and the two ends of the blade holder 11 The two end seal members 15 together form a closed ink chamber.

According to an embodiment of the present invention, the bidirectional doctor blade device 1 of the present invention further includes two displacement mechanisms 20 respectively arranged at two longitudinal ends of the doctor blade assembly 10 for enabling the doctor blade assembly 10 to work by pivoting movement Move between position and non-working position. Among them, in the working position, the doctor blade is pressed against the printing plate roller, and the doctor blade assembly forms a closed ink chamber with the printing plate roller surface between the two doctor blades 12; in the non-working position, the doctor blade assembly and the printing Plate roller separation.

Each displacement mechanism 20 includes a pivoting member for pivotally rotating the scraper assembly 10 between the working position and the non-working position. In the embodiment of the present invention, the pivoting member is a shaft and a bearing assembly, and each bearing assembly includes a bearing 21 and a bearing sleeve 22. In addition, the bearing assembly may also include a shaft end cover 23 and a bulkhead 24.

The bearing assembly is installed at one end of the first pile head (shaft) 8. The other end of the first pile head 8 is fixed to the first end (lower end in FIG. 1) of the support plate 6 in the lateral direction. The support plate 6 is fixed to a movable frame (not shown) by bolting.

The pivoting member is connected to the blade assembly via a connecting piece. In the embodiment of the present invention, the adjusting plate 7 is fixed on the bearing sleeve 22. The first end of the adjustment plate 7 in the lateral direction (in the figure 1 is the lower end) is fixed on the bearing sleeve 22 by bolt connection. The longitudinal end of the blade assembly 10 is fixed to the adjustment plate 7 via the end plate 2. In this way, the connection of the pivoting member to the doctor blade assembly is achieved.

Both ends of the second pile head (shaft) 9 are connected to the second end of the adjusting plate 7 in the lateral direction (upper end in FIG. 1) and the second end of the supporting plate 6 in the lateral direction (in FIG. 1) Upper end). The second ends of the adjustment plate 7 and the support plate 6 are respectively opposed to their first ends in the lateral direction.

According to the above configuration, the blade assembly 10 can be pivoted around the pivoting member (bearing assembly) via the adjustment plate 7, thereby achieving movement between the working position and the non-working position. When the doctor blade assembly is moved into its working position, the doctor blade assembly can be fixed in its working position by various common fixing devices. In the embodiment of the present invention, the scraper assembly is fixed in the working position by the screw and scraper device for fixing and the screw holes cooperating with the rack. When it is necessary to move the scraper assembly from the working position to the non-working position, unscrew the screw for fixing and pivotally move through the shifting mechanism.

According to the embodiment of the present invention, the bidirectional doctor blade device 1 of the present invention further has two adjustment mechanisms 30 for adjusting the contact pressure between the doctor blade of the doctor blade assembly 10 and the printing plate roller. Two adjustment mechanisms 30 are located at the two longitudinal ends of the doctor blade assembly 10 respectively. In addition, each adjustment mechanism 30 is located at the other end opposite to the end where the pivot member is located in the lateral direction, that is, the adjustment mechanism 30 is located at the second end of the adjustment plate 7 in the lateral direction.

As shown in FIGS. 1 and 3, the adjustment mechanism 30 includes an adjustment screw 31 and a fixed plate 32. The fixed plate 32 is located between the support plate 6 and the adjustment plate 7 in the longitudinal direction, and on the side away from the printing plate roller. The fixing plate 32 is fixed to the two-way scraper device, for example, fixed to the second end (upper end in FIG. 1) of the adjustment plate 7 in the lateral direction by bolting.

The adjusting screw 31 penetrates the second pile head 9 in the lateral direction and is in contact with the second pile head 9 Threaded connection. The front end of the adjusting screw 31 faces the fixing plate 32.

In this way, when the contact pressure between the doctor blade of the doctor blade assembly 10 and the printing plate roller needs to be adjusted, the adjustment screw 31 can be turned clockwise or counterclockwise to move toward or away from the fixed plate 32 in the lateral direction.

Taking an example where the contact pressure between the doctor blade and the printing plate roller is too large, at this time, the adjusting screw 31 is screwed to move toward the fixed plate 32 in the lateral direction. The front end of the adjusting screw 31 presses against the fixing plate 32 and pushes the fixing plate 32 in a direction to move the doctor blade assembly away from the printing plate roller. Since the fixing plate 32 is fixed on the adjusting plate 7, the adjusting plate 7 can be pivoted in a direction away from the printing plate roller around the pivot member. In this way, the blade assembly 10 moves in a direction away from the printing plate roller due to the pivoting of the adjustment plate 7, thereby reducing the contact pressure between the blade and the printing plate roller.

The adjustment mechanism 30 of the present invention can be used to finely adjust the contact pressure between the doctor blade and the printing plate roller after the doctor blade assembly is moved into the working position by the displacement mechanism. By adjusting the pushing of the fixing plate 32 by the screw 31 and combining with the pivoting member of the displacement mechanism, the blade assembly can be rotated around the pivoting member of the displacement mechanism at a small angle, thereby accurately contacting the blade with the printing plate roller Adjust to the desired pressure range.

In addition, the adjustment mechanism 30 of the present invention uses only two components of the adjustment screw 31 and the fixed plate 32 in combination with the existing pivoting member of the displacement mechanism for adjustment. Therefore, the number of parts of the adjustment mechanism of the present invention is small and the structure is very simple. In this way, the use of other separate and complicated adjustment mechanisms in the doctor blade device is avoided, thereby facilitating the structural arrangement of the two-way doctor blade device and saving costs.

In the embodiment of the present invention, as shown in FIG. 3, the bidirectional doctor device 1 of the present invention further includes two locking mechanisms 40 for locking the adjusted working position of the doctor blade assembly. Each lock The fixing mechanism 40 includes a lock nut 41, and a handle lever 42 is mounted on the lock nut 41. The lock nut 41 is penetrated by the adjusting screw 31 and is screwed with the adjusting screw 31. The lock nut 41 is located on the side opposite to the fixing plate 32 with respect to the second pile head 9. In other words, the lock nut 41 and the fixing plate 32 are located on both sides of the second pile head 9 in the lateral direction.

When the adjusting screw 31 is adjusted to an appropriate position, the lock nut 41 is rotated by the handle rod 42 to make the lock nut 41 tightly abut the second pile head 9, thereby locking the adjusted working position.

Although not shown in the drawings, the bidirectional doctor blade device 1 of the present invention may further include a constant temperature heating system for maintaining the temperature of the ink chamber between room temperature and 40 degrees Celsius. In this way, the ink can be kept at the required temperature, avoiding the influence of the seasonal environmental temperature on the ink, which is conducive to keeping the printing quality stable. In addition, the preheated ink dries faster after being exposed to the outside air, thus adapting to production at high vehicle speeds.

Although the pivoting member and the adjusting mechanism at one longitudinal end of the bidirectional doctor device are described with reference to the drawings, those skilled in the art may think that the corresponding pivoting member and adjusting mechanism may be provided at the other longitudinal end of the bidirectional doctor device according to this embodiment. I will not repeat them here.

Although the present invention has been described with reference to specific exemplary embodiments, the present invention is not limited by these exemplary embodiments. It should be recognized that those skilled in the art can make changes and modifications to these exemplary embodiments without departing from the scope and spirit of the present invention defined by the scope of patent applications or their equivalents.

Claims (9)

A bidirectional scraper device (1) for a textile printing machine. The bidirectional scraper device is used to supply liquid to a roller. The bidirectional scraper device includes: a scraper assembly (10). The scraper assembly includes a knife holder (11) ), Two scrapers (12) and a corresponding scraper pressure plate (13), the knife holder extends longitudinally, and the knife holder has a groove (14) on the side facing the roller, the The groove forms a space for accommodating the liquid to be supplied to the roller, and the two scrapers (12) are installed obliquely on both sides in the transverse direction of the opening of the groove (14) and along the longitudinal direction with the blade tips opposed Extending, the scraper pressure plate (13) is used to press the scraper (12) against the knife holder (13); one end sealing member (15), the end sealing member is placed on the knife holder At the two longitudinal ends of the blade for sealing the two longitudinal ends of the blade assembly (10); a displacement mechanism (20), the displacement mechanism has a pivoting member for the blade The assembly (10) is pivotally moved between a working position and a non-working position, and the pivoting part of the displacement mechanism (20) is provided on the At a lateral first end of the two-way scraper device, in the working position, the scraper (12) is pressed against the roller, and the two scrapers (12) of the scraper assembly (10) Together with the roller surface and the end seal member between the two scrapers, a closed liquid containing cavity is formed, and in the non-working position, the scraper assembly (10) is separated from the roller; and An adjustment mechanism (30) for adjusting the contact pressure between the blade and the roller when the blade assembly is in the working position, the adjustment mechanism (30) is disposed at the first end At a lateral second end opposite to each other, and wherein the reverse scraper is located close to the lateral first end of the bidirectional scraper device, and the forward scraper is located close to the location of the bidirectional scraper device The second lateral end is provided. The two-way scraper device (1) according to claim 1, wherein the adjustment mechanism (30) includes a nut screw mechanism and an adjustment portion (32) fixed to the scraper assembly (10). The interaction between the nut screw mechanism and the adjustment portion performs the adjustment of the contact pressure. The bidirectional scraper device (1) according to claim 2, wherein the nut screw mechanism includes a nut member and an adjusting screw (31), and the nut member is fixed to a mounting frame of the bidirectional scraper device , One end of the adjusting screw (31) presses against the adjusting part (32), wherein the adjusting screw (31) is screwed with the adjusting part (32) by screwing the adjusting screw (31) relative to the nut member Function, so that the doctor blade assembly (10) moves relative to the roller, thereby achieving adjustment of the contact pressure between the doctor blade and the roller. The two-way doctor device (1) according to claim 3, wherein the adjustment screw (31) presses the adjustment part (32) in a direction to move the doctor blade assembly away from the roller. The two-way scraper device (1) according to claim 1, further comprising a locking mechanism (40) for locking the working position of the scraper assembly (10). The two-way scraper device (1) according to claim 5, wherein the locking mechanism (40) includes a lock nut (41), and the lock nut (41) is screw-coupled with the adjusting screw (31) To achieve the locking of the working position of the scraper assembly in the locked position. The two-way scraper device (1) according to any one of claims 1, 2 to 6, wherein the two scrapers (12) are a reverse scraper and a forward scraper, respectively, wherein The reverse blade is used to scrape off excess liquid supplied to the roller, and the forward blade is used to remove impurities on the roller and perform sealing. The bidirectional blade device (1) according to claim 7, wherein the blade contact angle of the reverse blade is between 120 ° and 160 °, wherein the blade contact angle is that of the roller in the The angle between the direction of the tangential velocity at the point of contact between the scraper and the roller and the extension of the scraper from the back of the knife to the tip of the knife. The bidirectional blade device (1) according to claim 7, wherein the blade contact angle of the forward blade is between 20 ° and 60 °, wherein the blade contact angle is The angle between the direction of the tangential velocity at the point of contact between the scraper and the roller and the extension of the scraper from the back of the knife to the tip of the knife.