GB2128232A - Automatic cutting machine for road surfaces - Google Patents

Abstract

An automatic cutting machine for cutting road surfaces, particularly asphalted road surfaces, comprises a motor vehicle (1), which supports one or, preferably, two hydraulic hammers (12) situated at the two sides of the vehicle (1). A central control unit, in combination with various sensing and enabling means, controls the automatic repetition of alternated road surface cutting and vehicle advancement cycles. <IMAGE>

Description

SPECIFICATION Automatic cutting machine for road surfaces The present invention relates to an automatic cutting machine for road surfaces, in particular asphalted road surfaces.

It is known that, in order to execute works under an asphalted road surface, it is necessary to make preliminary cutting of the upper bituminous surface.

For such operation there have been recently made available relatively small asphalt-cutting machines, which are essentially based on the combination of a motor vehicle and of one or more hydraulic hammers situated in upright disposition - - along a longitudinal side of the vehicle.

Periodically, whilst the vehicle is stopped, the hydraulic hammer is controlled to move towards the road surface and to go into and to work in it to a prefixed cutting depth, after which the hammer is stopped and raised relative to the road surface.

At that time the operator controls the vehicle advancement to reach a new cutting position, where the above described cycle is repeated.

The machines of that kind presently on the market have the disadvantage of being functionally relatively unfinished, that is they provide little automation and rely on the operator to decide if and how the required working is to be executed. Besides they are able to effect a single linear cutting, which must be repeated along an adjacent parallel line in order to define a given excavation width.

The object of the present invention is to provide an asphalt-cutting machine, which is able to execute in a completely automatic way the whole work cycle, including the advancement of the machine between a cutting position and the successive one.

Another object of the present invention is to provide an asphalt cutting machine, which is not limited to a single linear cutting, but, in a single operation, is able to execute a pair of parallel cuttings defining a desired excavation width.

Still another object of the present invention is to provide an asphalt cutting machine, which operates in a way substantially independent of the structure of the underneath road surface, either flat or sloping, smooth or undulated.

The invention provides an automatic cutting machine for road surfaces comprising a control unit operable to cause the repeating development of working cycles automatically comprising a hammer downward movement to contact with the road surface, hammer actuation, furtherance of such downward movement for the penetration and the cutting engagement of the hammer in the road surface to a prefixed variable depth, raising and deactuation of the hammer for its return to rest in lifted position with respect to the road surface, and advancement of the machine by a variable prefixed distance for reaching a new cutting position.

The machine according to the invention is thereby able to execute automatically a succession of cutting cycies, moving automatically from one cutting position to a successive one. In such a way the operator has only the duty of keeping the exact driving direction, which is relatively simple and readily substantially free from mistakes.

According to a preferred embodiment the machine according to the invention is provided with at least two hammers, situated at a variable prefixed distance laterally of the vehicle. The machine is thus able to execute two parallel linear cuttings simultaneously which define a desired excavation width. The work of the machine is therefore rationalised and made quicker, with reduction of dead times and possibility of simultaneous use of an asphalt cutting machine and of an immediately successive digger.

Finally, according to said preferred embodiment, there is provided a sensing and enabling system, whereby the two-hammer working is dependent on the contact of both hammers with the underneath road surface. This allows the two hammers to execute cuttings of identical but adjustable depth, even if the road surface is sloping or has unevennesses or shrinkings. The resulting advantages are certainly evident.

These and other characteristics of the present invention will be better understood by referring to the enclosed drawings, in which: Fig. 1 is a schematic side elevation of a machine provided with a pair of operating groups with hydraulic hammer; Fig. 2 is a schematic plan of the machine of Fig. 1, Fig. 3 shows one of said operating groups of the machines of Figs. 1 and 2 in vertical section along line Ill-Ill of Fig. 2; Fig. 4 shows the same operating group in vertical section along line IV-lV of Fig. 3; Fig. 5 shows said operating group in horizontal section along line V-V of Fig. 4; Fig. 6 shows the hydraulic diagram of the central control unit of the machine of Figs. 1 to 5, and Fig. 7 shows schematically the mode of working of the machine on a sloping road surface.

With reference to Figs. 1 and 2, there is illustrated the assembly of a machine according to the invention, which comprises a combination of a motor vehicle 1, of suitable kind for use in normal road traffic, and of a pair of operating groups 2, one for each side of the vehicle, fastened to a support plate 3 transversely fixed in its turn to the vehicle 1. Even though not specifically illustrated in the drawings, it is intended that said operating groups 2 are at an adjustable relative spacing.

Each of the two operating groups 2, being symmetric with the other, is shaped as illustrated in Figs. 2 to 5, that is it comprises a box-like framework 4 fastened to a support plate 3 by means of brackets 5 coupled to flanges 6 of the plate 3 (Fig. 3), a box-like slide 7 sliding along vertical guides 8 disposed and fixed inside the framework 4, a hydraulic hammer 9 anchored between connection points 10 and 11 inside the slide 7 and provided with a cutting blade 12, a hydraulic cylinder 1 3 reacting between an upper cup 14 fixed to the framework 4 and a lower cup 1 5 fixed to the slide 7 (Fig. 4) and a telescopic sensor 1 6 having an outer element 1 7 fixed to the slide 7 and an inner element 1 8 pushed downwardly by spring means not shown. Two microswitches 1 9 and 20 are fixed in adjustable position to the outer element 1 7 of the telescopic sensor 1 6 (Fig. 3) and cooperate with the sliding inner element 1 8 of the sensor 1 6 for a purpose which will be described hereinafter. A further microswitch 53 fixed to the framework 4 cooperates in its turn with the top of the slide 7 to define the raised rest position of the hammer 9 (Fig. 3).

The two operating groups 2 and the vehicle 1 are functionally connected through a central control unit of electro-hydraulic kind, whose hydraulic, or preferably oleodynamic part, is illustrated in the hydraulic diagram of Fig. 6. From this latter diagram it can be noted that each operative group including a cylinder 13 and a hammer 9 has associated therewith a respective pair of electric or hydraulic-control distributors 21 and 22 connected to one of two coupled pumps 23 and to a discharge 24. Between the cylinder 13 and the distributor 21 there is also fitted a valve assembly including an adjustable neck 25 and a non-return valve 26. As shown, each of the two distributors 21 and 22 is able to assume three positions, that is a central or "neutral" position to which it is elastically biassed, a moved on right or "delivery" position and a moved on left or "discharge" position.The commutation of the distributor 22 to the delivery position is dependent on the contemporaneous presence, at the two inlets of a logic gate 27, of both signals 28 emitted by two micro-switches 1 9 associated with the two hydraulic hammers 9, when the microswitches 1 9 are engaged by the inner sliding element 1 8 of the respective sensor 16.The commutation of the distributor 22 to the discharge position is on the contrary dependent on the presence of a signal 29 emitted by the respective microswitch 20 associated with the respective sensor 1 6. As regards the distributor 21, it can be commutated to the discharge position by means of an outer control or other signal 30 emitted by a microswitch 35 which will be described hereinafter, while it can be commutated to the delivery position by the abovementioned signal 29. Both of the distributors 21,22 can be commutated to the neutral position under the control of a signal 44 emitted by the microswitch 53 when it is engaged by the top of the slide 7 in rest position.

In the diagram of Fig. 6 there is also illustrated a hydraulic cylinder 31 with a piston 32, on whose stem 33 there is fixed a cam 34 cooperating with two microswitches 35 and 36 placed at adjustably different heights. Under the control of a distributor 37 assisted by two non-return valves 50 and 51, and by using the functions of two non-return valves 38 and 39 and of a maximum pressure valve 40, the abovementioned piston 32 provides at a suitable moment the necessary operating pressure to hydraulic motor 41 acting through a transmission system 42 on the driving wheels 43 of the vehicle 1. As shown in Fig. 6, the distributor 37 is able to assume three positions, that is a central or "neutral" position, a moved on right or "delivery" position and a moved on left or "discharge" position.The commutation of the distributor 37 to the delivery position is dependent on the presence of a signal 44 emitted by the microswitch 53 when engaged by the slide 7 in rest position, and to the discharge position is dependent on the presence of a signal 30 emitted by the microswitch 35 when engaged by the cam 34; movement to the neutral position is in its turn caused by a signal 46 emitted by the microswitch 36 when engaged with the cam 34. There is finally provided a further distributor 47 with nonreturn valve 52, which can be controlled to commutate from the discharge position of Fig. 6 to a delivery position by a pump 48 in order to allow the independent operation of the hydraulic motor 41 and consequently of the driving wheels 43 of the vehicle 1.

By the effect of the hydraulic connections and of the hydraulic or electric controls illustrated in Fig. 6 the central control unit allows the machine to execute the cutting work of an asphalted road surface in an automatic manner, leaving the operator only the work of keeping the vehicle in the desired direction. The whole operative sequence is described below beginning from the condition of stopped vehicle, hydraulic hammers at rest in raised position with respect to the road surface (indicated by 49 in the drawings) and central control unit with the various distributors in the neutral positions shown in Fig. 6.

With the machine in such a condition at the beginning of the work, the distributor 21 is caused to commutate to the discharge position. The oil (or other fluid) contained in the lower chamber of the cylinders 13, below the respective pistons 45, starts to flow towards discharge with a speed fixed by the adjustable necks 25. Consequently the slides 7 of the two operative groups 2 begin to go down under gravity along the guides 8, moving the two hydraulic hammers 9 towards the ground and correspondingly causing the inner sliding elements 1 8 of the sensors 1 6, firmly in contact with the ground, to partially withdraw inside the respective outer elements 17.

Such downward movement continues until both the sensors 1 6 have reached the position in which their inner elements 1 7 engage the respective microswitches 19, which position is chosen so as to correspond with the contact of the blades 12 of the hammers 9 with the ground to be worked, and remains the same whether the ground is perfectly horizontal or it is inclined as in Fig. 7. It is evident that inclination of the ground, as well as unevenness, is compensated by a different sliding run of the slides 8 in their seats 4, while the final position of the hammers 9, and consequently of the telescopic sensors 1 6, with respect to the ground remains identical.This allows the machine to operate well in the same manner with any formation of the ground, being always sure that both the hammers have their blades in contact with the ground before the abovementioned engagement of the microswitch 1 9 starts the cutting work, as hereinbelow explained.

Once the contact condition of the two blades 12 with the ground 49 is reached, the two telescopic sensors 1 6 detect the engagement of both the microswitches 19, which emit respective signals 28, the contemporaneous presence of which, detected by the logic gates 27, causes the commutation of the distributors 22 to the delivery position. While the slides 7 move down under gravity, there are then operated the two hammers 9, which execute the cutting of the road surface at the two sides of the vehicle.

The cutting work ends at the reaching of a prefixed depth, when the sliding inner elements 1 8 of the two telescopic sensors 1 6 engage the upper microswitches 20. The position of the microswitches 20, which is suitably adjustable, defines therefore the cutting depth that the machines reaches during each work cycle.

The above mentioned engagement of the microswitches 20 causes the production of a signal 29, which changes the position of the distributors 22 and 21, putting the former to discharge and the latter to delivery. The hammers 9 return then to rest, while through the distributors 21 and the non-return valves 26 the two coupled pumps 23 feed oil under the pistons 45 in the cylinders 13 for the raising of the slides 7 and consequently of the hammers 9 and of the outer elements 1 7 of the connected sensors 1 6.

The slides 7 having reached the rest position, the raising ends when the microswitches 53 control, through a signal 44, the return of the distributors 21, 22, to the neutral position. At the same time, the same signal controls the commutation of the distributor 37 to the delivery position. Hence the piston 32 of the cylinder 31 is forced to move down and to send oil to the hydraulic motor 41, which through the transmission 42 drives the wheels 43 into rotation. This causes the vehicle 1 to advance from one cutting position to the successive one.

The advancement ends when the cam 34 mounted on the stem 33 of the piston 32 engages the microswitch 35, which through the signal 30 controls the commutation of the distributor 37 to the discharge position and the consequent raising of the piston 32. The advancement stroke of the vehicle therefore depends on the position of the microswitch 35 and can be easily changed with it.

While the abovementioned commutation of the distributor 37 causes the raising of the piston 32 to the upper end of its stroke represented by the microswitch 36, which through the signal 46 causes the return of the distributor 37 to the neutral position, the abovementioned signal 30 causes the return of the distributor 21 to the discharge position with consequent beginning of a new cutting-cycle followed by a further advancement of the vehicle, then by a further cutting cycle and so on.

In a completely automatic way and, independently of the shape of the road surface, the machine illustrated in the drawings is therefore able to execute simultaneously two cuttings of variable prefixed depth at variable prefixed mutual spacing and with also variable prefixed longitudinal spacing.

It results an absolutely reliable work, which can be performed suitably for different needs and, by the effect of the double parallel cutting, at double productiveness compared with the asphalt cutting machines presently on the market. In addition, since the machine according to the invention is able to execute simultaneously the two cuttings which define the excavation width, it can be immediately followed by a digger, in order to execute the whole cutting and excavation operation in the minimum time.

If desired, it is however possible to deactuate one of the two hydraulic hammers and therefore to use the machine to execute a single linear cutting.

By disconnecting the hammers, it is also possible to remove one of them, or both, from the supporting vehicle, so as to use them as simple road compressors.

Claims (10)

1. An automatic cutting machine for road surfaces, comprising a motor vehicle, at least one hydraulic hammer carried by said vehicle and means for moving said hammer through a working cycle comprising hammer downward movement to contact with a road surface, hammer actuation and the continuance of its downwards movement for the penetration and the cutting engagement of the hammer in said road surface to a predetermined depth, and raising the deactuation of the hammer for its return to rest in a raised position relative to the road surface, further comprising a control unit operable automatically to cause the vehicle advancement by a predetermined distance from one to a subsequent cutting position, and then to cause the repeat of said working cycle.

2. A machine according to claim 1, wherein said control unit comprises first control means operable to control the downward movement and the raising of the hammer, second control means operable to control the hammer actuation and third control means operable to control the vehicle advancement.

3. A machine according to claim 2, wherein said control unit comprises first means sensible to the downward movement of the hammer to contact with a road surface, second means sensible to the further downward movement of the hammer to said predetermined depth, third means sensible to the hammer return to said raised position and fourth means sensible to the advancement of the vehicle by said predetermined distance.

4. A machine according to claim 3, wherein said fourth sensible means acts on said first control means so as to cause the downward movement of the hammer towards the road surface, said first sensible means acts on said second control means so as to cause the actuation of the hammer, said second sensible means acts on said first control means so as to cause the raising of the hammer to said raised position, and said third sensible means acts on said third control means so as to cause advancement of the vehicle.

5. A machine according to claim 4, comprising a pair of hydraulic hammers positioned at opposed sides of the vehicle and movable downwardly towards a road surface and upwardly to a raised position relative to the road surface.

6. A machine according to claim 5, comprising enabling means operatively interposed between said first sensible means and said second control means to coordinate the actuation of the hammers in their downward movement to the contact with the road surface.

7. A machine according to claim 5 or claim 6, wherein said hammers are disposed at variable mutual spacing.

8. A maching according to any one of claims 5 to 7, wherein said hammers are slidably fixed to the vehicle for the independent use of one or both.

9. A machine according to claim 8, comprising means for disenabling one of said hammers.

10. An automatic cutting machine for road surfaces substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.