Scraping mechanism

A scraping mechanism for scraping off deposit material from a surface of a moving body, including a scraper having a bladed edge at the fore end thereof, a mechanism for pressing the scraper against the surface of the moving body, and a mechanism for reciprocatingly driving the scraper on and along the surface of the moving body in parallel relation therewith.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a mechanism for scraping off deposit material 
from the surface of a moving body such as a rotary drum, an endless filter 
cloth belt or the like. 
2. Description of the Prior Art 
As disclosed, for example, in U.S. Pat. Nos. 3,869,389; 3,699,881; 
3,601,039; 3,478,888 and 1,415,859, conventional scrapers are provided 
with a scraping member which is fixedly or detachably attached to a 
support member to scrape off sludge or other deposit of processed material 
from the surface of a rotary drum or an endless filter cloth belt, keeping 
a constant distance from the surface of the drum or belt. 
However, in a case where the processed material contains a large amount of 
foreign matter such as fiber, hair, paper, cloth or the like, a difficulty 
is often encountered in that the efficiency of the scraping operation is 
lowered considerably by the foreign matter which entangles around the 
blade of the scraper, forming space between the scraper blade and the 
surface of the rotary drum or the endless filter cloth belt. 
For instance, in the case of a belt press type dehydrator which is employed 
for the treatment of sludge in a waste water treating process, there 
occurs the necessity of removing with a scraper the sludge which deposits 
on the surface of a filter cloth belt as a result of a dehydrating 
treatment. On such an occasion, the more the foreign material entangles 
around the scraper blade, the more the latter is spaced away from the 
surface of the filter cloth belt, inviting clogging of the filter cloth 
belt with the residual deposits which cause degradations in the 
operational efficiency of the dehydrator. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a scraper mechanism 
with eliminates the abovementioned drawback of the conventional scrapers. 
It is a more particular object of the invention to provide a scraper 
mechanism which is particularly suitable for scraping off deposit material 
from the surface of a moving body such as a rotating drum of a rotary 
filter, an endless filter cloth belt of a belt press type dehydrator or 
the like. 
According to the present invention, there is provided a scraping mechanism 
for scraping off deposit material from a surface of a moving body, 
comprising: a scraper having a bladed edge at the fore end thereof; means 
for pressing the scraper against the surface of the moving body; and means 
for driving the scraper reciprocatingly on and along the surface of the 
moving body in parallel relation therewith. With this arrangement, the 
deposit material is effectively scraped off by the pressing means, while 
the entangling foreign matter at the bladed edge of the scraper is 
detached therefrom by the reciprocating movement of the scraper which is 
imparted by the drive means. Preferably, the scraper is reciprocated at a 
speed higher than the travelling speed of the moving body to detach the 
entangling foreign matter from the scraper blade in a more effective 
manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Hereafter, the scraping mechanism of the present invention is described 
more particularly by way of some preferred embodiments shown in the 
accompanying drawings, which are applied to a belt press type dehydrating 
machine for the convenience of explanation. 
Referring to FIG. 1, there is schematically shown a belt press type 
dehydrating machine with scrapers 23 and 24 provided at the sludge 
discharging end of upper and lower belts 1 and 2 which convey sludge 18 to 
the discharging end after compressive dehydration. With regard to the 
scrapers employed in the dehydrating machine of the first embodiment, 
reference is also had to FIG. 2 which shows one scraper in perspective 
view, FIG. 3 which shows the same scraper in side view, and FIGS. 4 and 5 
which show in side views the blade portion of the scraper for the 
explanation of its operation. 
In FIGS. 2 and 3, indicated by reference number 2 is the lower belt which 
is lapped around a discharge roller 13 rotating about a shaft 31 and the 
lower belt is held in contact with the discharge roller over an angle 
.alpha.. Provided within the range of the contacting angle .alpha. is a 
scraper 24' which is pressed against the surface of the lower belt 2 and 
secured to an angular metal mounting piece 35 fixedly provided at one end 
33 of a lever 32 which is rotatable about a horizontal shaft 34. The 
mounting piece 35 is constantly urged in the direction of arrow 39 by the 
cooperative action of a leaf spring 38 and a bolt 37 which is threaded 
through a lateral projection 36 of the lever 32 and engaged at its outer 
end with the leaf spring 38. The blade 27' of the scraper 24' is pressed 
against the surface of the belt 2 by the force of the leaf spring 38. 
The other end of the lever 32 is pivotally connected to a piston rod 42 of 
a pneumatic or hydraulic piston-cylinder 41 which is mounted on a machine 
frame. Consequently, the fore end 40 of the lever 32 is moved up and down 
arcuately by the reciprocating movements of the piston of the fluid 
cylinder 41 with the blade 27' of the scraper 24' pressed against the 
wrapped portion of the discharge roller 13. 
In this instance, in order to move the scraper 24' in the travelling 
direction of the lower belt 2, the speed of the piston motion of the fluid 
cylinder 41 is determined such that the scraper blade 27' moves along the 
lower belt 2 at a speed higher than the travelling speed of the lower belt 
2. 
In operation of the above-described embodiment, the upper and lower belts 1 
and 2 are tensioned so as to be taut by urging tension rollers 3 and 4 in 
the direction of arrows X and X', respectively, and the roller 5 is driven 
from a motor 16 to rotate in the direction of arrow 17, whereupon the 
upper and lower belts are both moved in the direction of arrow 17. The 
moisture content in the concentrated sludge 18 which is fed onto the lower 
belt 2 at a position forward of an overlapped portion A of the upper and 
lower belts 1 and 2 permeates through the lower belt 2 and drops therefrom 
by gravity. In the next phase, the concentrated sludge 18 is fed into a 
wedge-like gap B formed between the tension rollers 3 and 4 and the drive 
roller 5 by the movement of the upper and lower belts 1 and 2. The 
concentrated sludge 18 is sandwiched between the upper and lower belts 1 
and 2 are in repeatedly compressed and dehydrated as it is passed around 
the circumferences of squeeze rollers 6 to 10. The sludge which has been 
stripped of its moisture content in this manner is discharged from the 
machine in the form of dehydrated cakes 20 at the parting point 19 of the 
discharge rollers 11 and 13. 
At this time, the dehydrated sludge 29 deposited on the lower belt 2 is 
scraped off by the scraper 24', while the fibrous foreign matter 29 
entangling around the blade 27' of the scraper is pushed against the lower 
belt 2 and disengaged from the scraper blade 27' as shown in FIG. 4 as the 
scraper 24' is moved at a speed higher than the belt 2 in the travelling 
direction of the belt 2 with the blade 27' pressed thereagainst. In the 
next phase, the scraper 27' is moved in a direction opposite to the 
travelling direction of the belt 2 as shown in FIG. 5, so that the fibrous 
material which has been rubbed onto the belt 2 is scooped by the blade 27' 
and discharged in the direction of arrow 43 as shown in FIG. 5. 
By the reciprocating movement of the scraper 24' the entangling foreign 
material is detached from the scraper to restore its normal scraping 
function. The above-described sequential operations can be performed 
automatically in response to signals from a timer or a counter of roller 
revolutions or other control means. Although the blade portion 27' of the 
scraper 24' is arranged to make arcuate reciprocating movements about the 
shaft 31 in the foregoing embodiment, the present invention is not limited 
to such arrangement and has other possibilities with regard to the fulcrum 
point of the scraper. Further, although the foregoing description has been 
directed to the scraper 24' which is associated with the outer periphery 
of the discharge roller 13, the same applies to the other scraper 23 which 
is associated with the discharge roller 11. These two scrapers may be 
either driven from separate drive sources or simultaneously driven from a 
common drive source through a suitable link mechanism. 
FIG. 6 shows another embodiment of the invention, wherein a pair of 
scrapers which are connected by a link are simultaneously driven by a 
single pneumatic piston-cylinder. In this embodiment, the fore end of a 
piston rod 52 of a pneumatic piston-cylinder 51 which is mounted on a 
machine frame 50 is pivotally connected to a pair of links 53 and 54. The 
link 53 is pivotally connected to a lever 55 which is rotatable about the 
axis of the discharge roller 11, while the other link 54 is pivotable 
about a pin 56 which is fixed on the machine frame and has the opposite 
end 57 connected to a lever 59 which is rockable about the axis of the 
discharge roller 13. Designated by reference number 60 is a scraper which 
is securely fixed to a mounting piece 62 which is in turn securely fixed 
to the lever 55 for rocking movements about a shaft 61. The scraper 60 is 
pushed in the direction of arrow 64 by a bolt (not shown) acting on a leaf 
spring 63 which is fixed to the mounting piece 62, and pressed against the 
upper belt 1 which is wrapped around the discharge roller 11. On the other 
hand, a scraper 67 which is pressed against the lower belt 2 wrapped 
around the discharge roller 13 by a bolt (not shown) acting on a leaf 
spring 68 is secured to a mounting piece 66 for rocking movements about a 
shaft 65 which is fixedly secured to the lever 59. 
The dehydrated cakes which are discharged from the parting point 19 of the 
upper and lower belts 1 and 2 are dropped in the direction of arrow 69. 
In this embodiment, as the pneumatic cylinder 51 is operated telescopically 
as indicated by arrow 70, the lever 55 and the scraper 60 simultaneously 
undergo reciprocating arcuate movement as indicated by arrow 71 via the 
link 53. Similarly, the lever 59 and the scraper 67 which is attached to 
the lever 59 are reciprocated in the direction of arrow 72 via links 54 
and 58. 
FIGS. 7 and 8 show in side and front views a further embodiment of the 
invention which is also applied to a dehydrating machine and in which 
instead of utilizing the pneumatic cylinder, an operating shaft 74 of a 
hydraulic rotary actuator 73 is securely fixed to the center of a link 54 
to reciprocate the latter in the direction of arrow 75 directly by the 
operation of the rotary actuator 73, thereby rocking the levers 55 and 59 
through links 53 and 58 which are pivotally connected to the opposite ends 
of the link 54 for imparting reciprocating movements to the scrapers 60 
and 67, respectively. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.