Jaw crusher

Abstract: A jaw crusher with a pass-through preventing device which prevents a flat plate-shaped object from passing through without being crushed. Also disclosed is a jaw crusher with a tooth plate structure which is capable of effectively crushing a non-rigid object, for example, a lump of asphalt, without causing such an object to stick to the area between a cheek plate and a fixed tooth plate or a movable tooth plate. The jaw crusher comprises a plurality of forks which are provided at the lower end of a crushing space to prevent a plate-shaped object from passing through the crushing space without being crushed, and a fork shaft which is provided with one end of each fork and which is rotatably provided on the crusher body. The movable tooth plate is provided with cutting projections. A plate-shaped object is first broken by the cutting projections and then crushed by intermediate projections.

Description: The invention relates to a JAW CRUSHER according to the preamble of claim 1. The present invention relates to an improvement in jaw crusher. More particularly, the present invention relates to a jaw crusher for breaking asphalt pavement wastes, concrete scraps, etc. which has a pass-through preventing device to prevent an object of crushing from passing through the area between a fixed tooth plate and a movable tooth plate without being crushed, together with a crushing tooth plate structure that is improved in the crushing performance. Jaw crushers are known and used as machines for breaking rocks, asphalt pavement wastes, concrete scraps, etc. into pieces of desired size. These days, a large amount of concrete scrap and asphalt pavement waste are produced by dismantling of concrete buildings, repair of asphalt pavements, etc. Treatment of these wastes, particularly in urban areas, gives rise to a social problem because of the generation of noise and dust during the treatment, difficulty in securing a place for dumping wastes, a high cost of waste transportation, etc. For this reason, these wastes are desired to be speedily treated and reused at or near the site where the wastes are produced, as much as possible. When such wastes are crushed with a jaw crusher, a thin waste material may pass through the crushing space between a fixed tooth plate and a movable tooth plate to come out of a discharge opening without being crushed. When the lower end portion of the fixed or movable tooth plate has become worn, the size of the discharge opening enlarges, so that a plate-shaped waste material, for example, a concrete lid for a road side ditch, may pass through the crushing space to drop out of the discharge opening without being crushed. A jaw crusher wherein a square bar is disposed in an outlet of an object of crushing not to prevent the object from passing through without being crushed but to control the size of pieces of the crushed object is known as Japanese Utility Model No. 63-185453. In this mechanism, no retracting mechanism is provided and hence the square bar is constantly exposed to the object of crushing. The JP-A 54-39261 discloses a jaw crusher having an adjusting body 6 positioned below the crushing gap. The adjusting body 6 is used to choke the gap and to keep back particles which have not yet been sufficiently crushed. A tooth plate structure which is designed to break an object by bending is known. For example, Japanese Patent Laid-Open Application No. 60-147252 proposes a tooth plate structure which is designed to cut blast furnace slag by bending. However, this tooth plate structure is adapted for breaking by bending only and is not very effective in crushing. The present invention provides a jaw crusher which is free from the above-described problems of the prior art. The jaw crusher according to the invention is characterized by the features of claim 1. According to one aspect of the present invention, there is provided a jaw crusher for breaking a non-rigid object comprising: a body; a fixed tooth plate which is secured to the body; a movable tooth plate which is swingably provided at an acute angle to the fixed tooth plate to provide therebetween a crushing space for breaking an object which is to be crushed; a swing jaw to which the movable tooth plate is secured; a driving mechanism for swinging the swing jaw; a motor for driving the driving mechanism; a plurality of forks which are provided at the lower end of the crushing space to prevent the object from passing through the crushing space without being crushed; and a fork shaft which is provided with one end of each of the forks and which is rotatably provided on the body. It is an object of the present invention to provide a jaw crusher with a pass-through preventing device which prevents a flat plate-shaped object from passing through without being crushed. The present invention provides a jaw crusher with a pass-through preventing device which is designed so that the impact of a flat plate-shaped object when thrown in is lessened. In the jaw crusher of the present invention, a pass-through preventing device is disposed at the object discharge position, so that even a thin plate-shaped object can be effectively crushed without passing through in vain. In addition, since the object of crushing is received by means of hydraulic pressure, pneumatic pressure and spring force, the forks can move effectively without being damaged. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view of the jaw crusher with a pass-through preventing device according to the present invention, showing a first embodiment of the pass-through preventing device; Fig. 2 is a side view of the jaw crusher shown in Fig. 1; Fig. 3 shows the external appearance of a second embodiment of the pass-through preventing device; Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3; Fig. 5 shows the external appearance of a third embodiment of the pass-through preventing device; One embodiment of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a front view of one embodiment in which the present invention is applied to a crusher that is generally called "single-toggle type jaw crusher" (hereinafter referred to as "jaw crusher"). Fig. 2 is a side view of the jaw crusher as viewed from the left-hand side of Fig. 1. The jaw crusher has a body 1 that is made of steel plate. A fixed tooth plate 2 is secured to a wall surface inside the body 1. A movable tooth plate 3 is disposed in opposing relation to the fixed tooth plate 2. A wedge-shaped crushing space 4 is defined between the fixed and movable tooth plates 2 and 3. The movable tooth plate 3 is secured to the front side of a swing jaw 5. The upper end of the swing jaw 5 is rotatably supported by an eccentric shaft 6. The lower end of the swing jaw 5 is supported by the forward end of a toggle plate 7 which abuts against it. The rear end of the toggle plate 7 is supported by the body 1. The eccentric shaft 6 is supported by the body 1 through bearings 8. A flywheel 9 is attached to one end of the eccentric shaft 6, and a V-belt pulley 10 is secured to the other end thereof. The V-belt pulley 10 is driven to rotate by a motor (not shown) through a V-belt. The eccentric shaft 6 is rotated in response to the rotation of the V-belt pulley 10. In response to the rotation of the eccentric shaft 6, the swing jaw 5 moves up and down as well as back and forth. Since the swing jaw 5 is supported by the toggle plate 7 from the back, the back-and-forth motion of the swing jaw 5 results in approximately circular motion along a circle the radius of which is defined by the toggle plate 7. The swing jaw 5 performs the vertical motion and the circular motion at the same time in response to the rotation of the eccentric shaft 6. The forward end of a rod 11 is rotatably attached to the rear portion of the lower end of the swing jaw 5 through a joint. A washer 14 is attached to the rear end of the rod 11 by a nut. A coil spring 12 is interposed between the washer 14 and a bracket 13. Since the bracket 13 is secured to the body 1, the rod 11 constantly pulls the swing jaw 5 rearwardly. Accordingly, the swing jaw 5 performs the above-described approximately circular motion without separating from the forward end of the toggle plate 7. Pass-through preventing device When the above-described jaw crusher is used for a long time, the lower end portions of the fixed and movable tooth plates 2 and 3 become worn into shapes such as those shown by the one-dot chain lines a in Fig. 2. As a result, the size of a discharge opening 16 enlarges, so that an object to be crushed, particularly a planar slab, which is thrown into a loading opening 15 may pass through the discharge opening 16 without being crushed. A pass-through preventing device 20 is designed to prevent an object from passing through the discharge opening 16 without being crushed. A fork shaft 21 is rotatably supported by bearings 22. The bearings 22 are secured to the lower side of the body 1 by means of bolts. A bush for buffer action, which is made of a hard rubber material, is inserted in each bearing 22 for the purpose of vibration isolation. Three equally spaced forks 23 are integrally connected to the fork shaft 21 by keys and bolts (not shown) or by welding. The forks 23 are spaced apart from each other at a predetermined distance in order to block the passage of an object to be crushed through the discharge opening 16. One end of a link 24 is secured to one end of the fork shaft 21. The distal end of a piston rod 26 of a cylinder 27 is rotatably connected to the other end of the link 24 through a shaft 25. The cylinder 27 drives the fork shaft 21 to rotate. The rear end of the cylinder 27 is rotatably connected to a bracket 29 through a shaft 28. The bracket 29 is secured to either the body 1 or a frame 31 on which the jaw crusher is installed, by means of bolts (not shown) through a vibration insulator 30. Operation of the pass-through preventing device 20 When the piston rod 26 is contracted by introducing hydraulic pressure into the cylinder 27, the link 24 is pivoted about the fork shaft 21. In consequence, each fork 23 is pivoted to a position where it faces the discharge opening 16 (i.e., the position shown in Fig. 2). If a relatively thin object to be crushed is thrown into the loading opening 15 in this state, it drops through the crushing space 4 and collides against the upper surfaces of some forks 23, thereby being stopped from passing through without being crushed. The forks 23 against which the object collides receive the impact. The impact force acts in such a manner as to twist the fork shaft 21 and pivot the link 24. In consequence, the link 24 acts in such a manner as to drive the piston of the cylinder 27 through the piston rod 26. Although the piston compresses the oil in the cylinder 27, since the oil is sealed by a switching valve (not shown), the hydraulic pressure functions as a damper, so that the piston cannot move. In addition, the damper 30 lessens the impact. The object, which is blocked by the forks 23, is crushed in the crushing space 4 between the fixed and movable tooth plates 2 and 3, and the pieces of the crushed object are discharged through the discharge opening 16. Fig. 3 shows the external appearance of a second embodiment. Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3. The forks 23 in the first embodiment are rigidly secured to the fork shaft 21, whereas the forks 23 in the second embodiment are rotatably provided on the fork shaft 21. A coil spring 35 is interposed between each fork 23 and the fork shaft 21. One end of the coil spring 35 is inserted into a fixing hole 36 that is provided in the fork shaft 21. The other end of the coil spring 35 is inserted into a insertion hole in the fork 23. In an assembled state where the coil springs 35 have been inserted in position, the forks 23 and the fork shaft 21 do not move relative to each other. The structures of the other portions are the same as those in the first embodiment. When the cylinder 27 is driven, the forks 23 are pivoted until they are pressed against a rod-shaped stopper 37. The forks 23 are thus stopped from pivoting in a state where the coil springs 35 are slightly wound up. Thus, in this state the forks 23 are constantly subjected to torsional torque. In the second embodiment, even if a thin plate-shaped object of crushing collides against a fork 23, the torsional impact on the fork 23 is lessened by the coil spring 35. After the collision, the fork 23 is returned to the angular position of the stopper 39 by means of the resilient force from the coil spring 35. In addition, the impact of the object is deadened by the buffer action of the cylinder 27. It should be noted that a replaceable liner 23a, which is replaced with a new one when becoming worn, is attached to the distal end of each fork 23 by means of bolts. [Third embodiment of the pass-through preventing device] Fig. 5 shows the external appearance of a third embodiment. The lower end of a hand-lever 40 is secured to one end of the fork shaft 21. A fixing bolt 41 is rotatably provided in the intermediate portion of the hand-lever 40. The fixing bolt 41 is selectively screwed into either one of the two positioning holes 42 to secure the hand-lever 40 to the body 1. When the pass-through preventing device is not used, the fixing bolt 41 is loosened and the hand-lever 40 is pivoted about the fork shaft 21 to retract the forks 23 from the discharge opening 16. [Other embodiments of the pass-through preventing device] Although the cylinder 27 in the first and second embodiments is an oil-hydraulic cylinder, a pneumatic cylinder may also be employed. The arrangement may also be such that the cylinder 27 in the first embodiment is replaced with a spring and the device for pivoting the forks 23 is adapted be hand-operated as in the third embodiment.

Claims: Jaw crusher for breaking a non-rigid object comprising a) a body (1); b) a fixed tooth plate (2) which is secured to said body; c) a movable tooth plate (3) which is swingably provided at an acute angle to said fixed tooth plate to provide therebetween a crushing space (4) for breaking an object which is to be crushed; d) a swing jaw (5) to which said movable tooth plate is secured; e) a driving mechanism (10) for swinging said swing jaw; f) a motor for driving said driving mechanism; g) a plurality of forks (23) which are provided at the lower end of said crushing space (4) to prevent said object from passing through said crushing space without being crushed; characterized by h) a fork shaft (21) to which one end of each of said forks (23) is connected and which is rotatably supported by bearings (22) which are secured to the lower side of said body (1); i) a shaft driving mechanism (27,40) which is connected to one end of said fork shaft (21) to rotate it, thereby driving said forks to rotate, and to hold it in a fixed position j) buffer means (30,35) being provided for lessening impact energy that is generated when said object collides against said forks (23); k) the forks (23) being rotatably arranged on the shaft (21) and biased by springs (35) to be pressed against a rod-shaped stopper (37) to be constantly subjected to a torsional force, the springs (35) thereby forming said buffer means. Jaw crusher as claimed in claim 1, characterized in that the shaft driving mechanism is a hydraulic cylinder (27). Jaw crusher as claimed in claim 1, characterized in that the shaft driving mechanism is a pneumatic cylinder (27). Jaw crusher as claimed in claim 1, characterized in that the shaft driving mechanism is a spring. Jaw crusher as claimed in claim 1, characterized in that the shaft driving mechanism is a hand lever (40). Jaw crusher according to one of the preceding claims, characterized in that a replacable liner (23a) is attached to the distal end of each fork (23).

Inventors: HIRAKAWA MASANAO, HIRANO KAZUJISA, ISEBABA YOSHIHIRO, KITSUKAWA TOMOHIRO, HIRAKAWA, MASANAO, HIRANO, KAZUJISA, ISEBABA, YOSHIHIRO, KITSUKAWA, TOMOHIRO
Applicants: NAKAYAMA IRON WORKS LTD, NAKAYAMA IRON WORKS, LTD.
Application year: 1991
Main classification: B02C1
IPC codes: B02C1