BRPI0900911A2 - pump head and procedure for carrying it out - Google Patents

Abstract

PUMP HEAD AND PROCEDURE FOR PERFORMING THEM. The present invention relates to a pump head (1) formed by a molded metal body (2) provided with a transport surface (14) of a fluid to be pumped comprising a pumping chamber (3), a suction channel (12) and a discharge channel (13) and furthermore formed by an extract of plastic coating material (18) which is overprinted substantially exclusively on the transport surface (14) of the molded metal body (2). Such a head (1) is carried out by means of an overprinting procedure of the suitably shaped metal body (2) with the plastic material extract (18).

Description

Report of the Invention Patent for "PUMP HEADS AND PROCEDURE FOR CARRYING OUT THE PUMPS".

Application field

The present invention relates to a pump head and a procedure for carrying it out according to the preambles of the independent claims.

The pumphead in question is intended to be advantageously used in the production of pumps, in particular of membrane or plunger, used in the agricultural sector for irrigation or disinfestation of cultivations.

State of the Art

As is well known, the head of a pump is subjected to strong pressures generated by the reciprocating movement of a membrane or a piston within a pumping chamber for the purpose of suctioning fluid through a suction channel, for example connected to a reservoir, and for example, channel it at the outlet through a discharge channel connected to an irrigation distributor.

Pump heads made of bronze, aluminum or brass are known in the market to ensure adequate mechanical resistance during pump operation.

For some applications, especially for the agrarian sector, the fluid to be pumped typically consists of aqueous solutions containing chemical compounds (eg in the form of organic and inorganic electrolytes, crystalline substances, inert sands) capable of harming and corroding metallic materials. and consequently de-damage the pump head over time.

To remedy this drawback, pump heads with increased wear resistance due to chemical compounds have been introduced to the market. Such heads were obtained through various production techniques.

For example, techniques are known which provide for the formation of a metal coating on the head, which is in turn coated with a silicone resin extract or techniques for providing for the head arrangement of a magnetite protective extract. Other techniques provide for the construction of a coating composed of the decobalt / nickel / molybdenum mixture by means of spraying procedures, ie the formation of carbide or metal boride or metal alloy coatings. In addition, plasticization procedures are known which provide for the pumphead to be heated and then submerged in a plastic earth compound which, upon contact, distributes to the pumphead surface forming a continuous coating of a few tenths. of millimeters.

Such coatings, however, due to their extremely low thickness, do not guarantee good performance in terms of wrinkling, as they are easily subject to wear due to the pressures and friction exerted by the suction fluid in the pumping chamber. In addition, the techniques of making such coatings require numerous and complicated processes to be made, which make it relatively difficult to control the quality of the final product.

In order to remedy the aforementioned drawbacks, pump heads consisting of a rigid plastic support structure with a concave portion, which defines a pumping chamber communicating with a suction channel and a discharge channel, are known. The plastic material of which the support structure is formed gives the pressure chamber walls a good resistance against chemical corrosion due to the action of the substances contained in the liquid to be pumped. A metal frame, furthermore, provided with reinforcing ribs, is placed within the plastic material matrix of the support structure to give the head greater mechanical strength in the subjected to higher pressures.

This solution, however, also proves to be in practice not without its drawbacks.

A first drawback stems from the fact that the head in question is mostly made of plastics material, and despite having a reinforcing frame, it is not able to withstand pumping chamber pressures greater than 1.5 mPa (15 bars). In the agrarian area, by contrast, irrigating fields or treating crops with antiparasitic liquids requires the use of pumps capable of creating high pressure in the liquid to be pumped. Consequently, the heads of such pumps must be able to withstand very high pressures (eg up to 4.0 mPa (40 bars)).

A further drawback stems from the fact that the head realization process provides for the use of very complicated and costly molds. In fact, molding of the support frame in plastic material provides for the disposition of the metal frame to be coated between two cavities of a mold. They are molded to define the surface of the pumping chamber and the outer surface of the pumphead. In addition, two punches mounted on the trolleys on opposite sides of the head are required to perform the planned suction and discharge channels. The plastic material injected into the mold completely surrounds the metal frame forming the head support structure. Both mold cavities have very complicated contours in order to precisely define the thickness of the plastic in all parts of the head and the numerous reinforcement and heat exchange ribs. This entails an increase in the design and constructive complexity of the molds with a consequent increase in production costs. Moreover, the need to use two cars in the molding phase implies a further increase in production costs.

Presentation of the Invention

The main object of the present invention is therefore that of inconvenient remedies manifested by solutions of known type by providing a pump head which is operationally reliable under all conditions of use and operation of a pump.

Another object of the present invention is to provide a fully operational and completely safe pump head in time.

A further object of the present invention is to provide a simple pump making procedure that is cost effective at the manufacturing level.

Brief Description of the Drawings

The technical characteristics of the invention according to the above objectives are clearly localizable in the contents of the claims illustrated below and the advantages thereof will be more apparent from the following detailed description, made with reference to the accompanying drawings, which represent a purely exemplary embodiment. nonimmititive where:

Figure 1 shows an anterior perspective view of the pump head, object of the present invention;

Figure 2 shows a rear view of the pump head, object of the present invention;

Figure 3 shows a sectional view of the pump head, object of the present invention, according to the lines III - III of Figure 1;

Figure 4 shows a sectional view of the pump head, object of the present invention, according to the lines IV-IV of Figure 1;

Figure 5 shows a cross-sectional view of the mold employed during the procedure for making the pump head object of the present invention;

Figure 6 shows a detail of Figure 5 concerning the demolding chamber.

Figure 7 shows a top view of the mold of Figure 5.

Detailed Description of a Preferred Embodiment Example

With reference to the accompanying drawings, the number 1 of the pumphead, which is the subject of this invention, has been indicated in its complex No 1.

The head 1 in question must be coupled to a pump sump, provided with pumping means known to a metering technician and therefore not described in detail.

In accordance with the accompanying figures, the head 1 comprises a molded body 2, provided with an outer surface 11 and a conveying surface 14 of a liquid to be pumped. The latter transport surface 14 within head 1 defines a pumping chamber 3 together with the pump housing on which head 1 is mounted, a suction channel 12 and a discharge channel 13 through which the fluid to be pumped enters and exits the pumping chamber 3 respectively.

The fluid to be pumped typically consists of a liquid, for example water or, more generally, aqueous solutions, in which chemical compounds are dissolved for the purpose of obtaining agricultural products (eg antiparasites, fertilizers, etc.).

In detail, the suitably shaped metal body 2 is provided on two substantially parallel sides whose first 6 is turned outwardly and thus remains in sight, and the second 7 is mechanically coupled to the pump housing. For this purpose, between the two sides, 6 and 7, there are made in the suitably molded metal body 2 some threaded holes 8 through which securing means such as nut bolts or screws are introduced to secure the head 1 to the crankcase. bomb.

On the second side 7 of the molded metal body 2, a substantially hubcap-shaped concave 10 is made which delimits the pumping chamber 3. The latter is enclosed within a membrane retained between the molded metal body 2 of the head 1 and the pump housing.

Advantageously, the suction channel 12 and the discharge channel 13 leave the pumping chamber 3 in parallel until they flow into the second side 7 of the molded metal body 2, respectively, with a suction port 4 and a discharge port 5 arranged near the same side side 17 2. The particularly close arrangement of the suction port 4 (the preferred internal diameter is 30 mm) and the discharge port (5) (the preferred internal diameter 28 mm) which allows the use of only one molding. manifold for the suction and distribution of fluid, as a consequence of reducing the space occupied by the pump.

The molded metal body 2 is furthermore provided with a first opening 15 and a second opening 16 made on the side 17e and communicating respectively with the suction channel 12 and the discharge channel 13. Such openings 15 and 16 allow access to two seats 37 placed for the interception of the suction channel 12 and discharge 13, in which are placed, respectively, a first and a second check valve, consisting of a stainless steel trunk-spherical body, not shown in the attached figures, as they are known. The first valve allows fluid to enter the pumping chamber 3 through the suction port 4, while in contrast the second valve allows the fluid to exit the pumping chamber 3 towards the discharge port 5. These valves are held in position at the corresponding seats 37 by a cover, not shown, mounted on the side side 17 of the metal framed body 2, which keeps the first 15 and second 16 openings closed during normal operation of the pump.

Advantageously, the molded metal body 2 is made of aluminum which gives the head 1 the mechanical strength necessary to withstand the high hydrostatic pressures (eg up to 4.0 mPa (40bars)) achieved during pump operation. In addition, aluminum is a relatively light metal and thus enables to make a head 1 for particularly low weight pumps.

In line with a relatively preferred form of the present invention, on the first side 6 of the molded metal body 2 there are provided reinforcing ribs 9 which define a reticular structure capable of increasing the mechanical strength of the head 1.

In keeping with the basic idea of the present invention, head 1 comprises an extract of plastic coating material 18 which is substantially exclusively printed on the transport surface 14. According to the particular embodiment illustrated in the attached figures, such surface Conveying 14 is defined by the concavity 10 of the pumping chamber 3, the suction 12 and discharge channels 13, the suction ports 4 and discharge 5, and, advantageously, the openings 15 and 16. It thus defines, as it has been lined with plastic material extract 18, the surface intended to be wetted by the pumped liquid and, together with the closing chamber of the pumping chamber 3, delimits the space through which such fluid flows during the normal operation of the pump.

The outer surface 11 of the head 1 is subject to normal weathering and therefore does not need to be coated with the plastic extract 18. Thus molding the latter exclusively under the conveying surface 14 of the molded metal body2 ensures optimum strength performance. head chemistry 1 and, at the same time, allows for savings in terms of materials used, with a consequent reduction in production costs compared to currently produced heads.

Advantageously, the plastic material extract 18 is made of polypropylene with the objective of guaranteeing the head 1 an excellent chemical resistance in relation to substances contained in the fluid to be pumped, which, in the absence of plastic material 18, would corrode the molded metallic body 2, determined its progressive degradation.

According to a particularly useful feature, the plastic material extract 18 is chosen to ensure adequate chemical resistance and at the same time to ensure perfect adherence to the molded body 2 without cracking also in the presence of severe pressures to which it is subjected. pumphead 1 during pump operation. In addition, such molten plastic material, once injected into the molds, has sufficient fluidity to reach the entire conveying surface 14, allowing uniform molding of the coating extract18. In keeping with an advantageous feature of the present invention, the material extract Plastic 18 has a thickness between 2-4 millimeters, preferably 3 millimeters. The thickness values of the plastic material extract 18 substantially less than 3 millimeters (and in particular beyond the above range) do not allow the molding of the plastic material extract 18 to be distributed evenly over the entire transport surface 14 of the molded metal body 2. , as will be explained in detail below with reference to the different stages of the procedure. Moreover, thicknesses of the plastic material extract 18 below the above values would not guarantee resistance to the chemical agents due to the inevitable porosity and always present superficial defects of the plastic material, through which the fluid to be pumped would come into contact with the molded metal body. 2 eroding it. In contrast, a thickness of the plastic material extract 18 greater than 4 millimeters would have no practical advantage and thus entailed a waste of material and a useless increase in costs.

Preferably, the plastics material extract 18 comprises at least one spare element 39 which defines a countershaft 40 for securely anchoring to the molded metal body 2 to be perfectly adherent to the latter.

More precisely, with reference to FIG. 4, the spare member 39 extends toward the molded metal body 2 from the plastic extract 18 in the hollow 10 of the pumping chamber 3. This is shaped like a mushroom with a rod 41 bounded by a passage 42 made in the molded metal body 2, from the center of the concavity 10 of the pumping chamber 3, with a head43 attached without continuity solution to the rod 41, defined by a step44 made at the bottom of a recess 45 of the molded metal body 2.

During the overprinting process, the molten state plastic material fills the passage 42 and covers the recess step 45. The head 43 of the mushroom-shaped spare element 39 retains the plastic extract 18 mechanically adhering to the convex surface of the pumping chamber 3 .

Also part of the present invention is a procedure for carrying out the pump head 1 of the above type.

In the following, for the sake of simplicity, reference will be made to the printhead 1 previously described with reference to the accompanying figures, although it is to be understood that the procedure in question is capable of performing also pump heads other than those represented herein.

In accordance with the present invention, the procedure comprises a first phase of forming the molded metal body 2 substantially in the shape of the head 1. Conveniently, such a phase is performed by a combined melt and pressure molding process in which the molten metal is introduced at high speed. in a mold and solidified under pressure. After solidification, with the cooling of the mold by means of a water circulation system, the molded metal body 2 is removed from the mold. The molded metal body 2 obtained in this way is subjected to the following later stages of the realization process, intended to mold the extract into plastic material 18 on the same.

Conveniently, a preheating phase of the molded metal body 2 is provided for the purpose of bringing it substantially to the same temperature as the molds used in the successive stages of the process. This prevents strong thermal excursions from causing significant changes in the volume of the molded metal body 2 during consecutive stages of the process, causing mold sticking problems.

In line with the exemplary embodiment illustrated in FIG. 5, there is provided a positioning phase of the suitably shaped metal body 2 within a die 19 for its support and retention, whose die 19 is mounted on a die holder 20. More precisely, as shown in FIG. In particular, as shown in Figure 6, the suitably shaped metal body 2 is arranged with its first side 6 towards the die 19. The latter is molded with internal projections 35 to engage with corresponding portions of the outer surface 11 of the metal body 2, a. in order to exert a reaction force to the strong pressures created during the successive injection phase of the plastic material. Conveniently, such internal protrusions 35 define fulcrum and deferral points which receive the reinforcing ribs 9 realized on the first side 6 of the shell. outer surface 11 of the metal framed body 2.

Next, a closure phase of the die 19 with at least one counter current 21 and with a carriage 22 is provided. The counter current 21 and the carriage 22 have shapes corresponding to those of the matrix 19 and isolate the molded metal body 2 into a molding chamber where it remains A gap 23 is defined between the countercurrent 21 and the carriage 22 on the one hand and the molded metal body 2 on the other.

Advantageously, the carriage 22 is mounted such that it can slide onto the mold holder 20 in suitable guides 25, which allow its movement in terms of approach and distance from the molded metal body 2, in order to be resistant against the mold. matrix 19 at the end of the positioning and retraction phase in a successive phase.

Referring to FIGS. 5, 6 and 7, carriage 22 is provided with a first punch 26 and a second punch 27, which exit from a common base 28 attached to carriage 22 and are aligned, respectively, with the first and second aperture 15 16. During the positioning phase the carriage 22 moves towards the molded metal body 2 with the aim of supporting the base 28 on the side side 17. In such a position the first 26 and the second 27 punches enter the respective openings 15, 16 and extend into the suction channel 12 and discharge 13 until they reach the pumping chamber 3. The first 26 and the second 27 punches are counter-molded with respect to the suction channel12 and discharge 13 and are maintained at a preset distance by the transport surface. 14 in order to define the thickness of the plastic material extract 18.

The countercurrent 21 is disposed on top of the die 19 and the base 28 of the carriage 22 on the second side 7 of the molded metal body 2. Preferably, the countercurrent 21 is provided with a first inclined wall 38, which is intended to join a second counterpart inclined wall of carriage 22 to push the latter to fit the molded metal body 2.

A second important aspect of the present invention is that the current 21 is provided with a correspondingly shaped convexity with respect to the substantially hemispherical shell-shaped concavity 10 of the pumping chamber 3 and is maintained with a preset distance from the conveying surface 14. The counter-matrix 21 is furthermore provided with two protruding portions 30 which insert into the suction ports 4 and discharge 5 until they are mechanically coupled to the two punches 26, 27, thereby forming a single body without continuous solution. Such protruding portions 30 are also kept at a predetermined distance from the conveying surface 14 of the molded metal body 2, to allow molding of the plastic material extract 18 to the desired thickness.

The predefined distance quoted above, corresponding to the thickness of the plastic extract 18, is chosen from 2 - 4 millimeters, preferably 3 millimeters, to ensure a correct molding of the plastic extract 18 on the entire transport surface 14. In fact, a shorter distance would not allow the plastic material, during the injection phase, to uniformly reach the entire transport surface 14, completely filling the space 23. This would entail the formation of discontinuities or gaps in the plastic material extract 18, which would no longer be able to ensure adequate retention of the agents. chemicals contained in the fluid to be pumped as previously considered.

In order to overprint the plastic material only on the conveying surface 14 of the molded metal body 2, the countercurrent 21 is provided with peripheral retaining portions 32 in adherence with corresponding areas on the second side 7 of the suitably shaped metal cup 2, which surround the concavity 10 and the opening holes. suction 4 and discharge 5, which are not subject to contact with the pumped fluid. For the same reason also the base 28 of the carriage 22 is adhered to the side side 17 of the molded metal body 2 in the areas surrounding the openings 15 and 16.

After the positioning phase of the countercurrent 21 and decar 22, a phase of injection of the plastic material into the melt in space 23, defined by the conveying surface 14 of the molded metallic body 2, the countercurrent 21 and the carriage 22, is foreseen to form. the plastic material extract 18. Injection of the fluidly shaped plastic material is made with pressures capable of allowing it to flow evenly into space 23, reaching the entire transport surface 14 which must be coated. For this purpose, the injection is preferably made through a central duct 34 made in the countercurrent 21, in the high passage 42 made in the pumping chamber 3.

Usefully, one of the internal protrusions 35 of the die 19 is located at the end of the recess 45 of the suitably shaped metal body and to delimit the head 43 of the spare member 39.

After the plastics material has filled the entire space23, the injection will be stopped and then there will be a cooling-down phase of the plastics extract 18, in which the latter solidifies closely permanently to the conveying surface 14 of the molded metal body 2.

Thereafter, a removal phase of the carriage 22 and the counter-current 21 of the molded metal body 2 is provided to allow the extraction of the head 1 from the die 19 by means of a plurality of pullers that pass through corresponding ducts 36 made in the die 19 and mold holder 20.

Advantageously, the object procedure of the present invention comprises an anodizing phase of the molded metal body 2 after its extraction of the matrix 19. Such anodizing phase involves the formation of a thin oxide film on the first and second side 6, 7 of the metal body. molded 2. This oxide film is sufficient to protect the head 2 metal body 2 from atmospheric agents.

In accordance with the foregoing embodiment procedure, the shape of the plastic extract 18 is determined by carriage 26 and 27, convexity 29, counter-current portions 30 and 32, and the conveying surface 14 of the appropriately shaped metal body 2 Molding of the plastics material does not require, according to the present invention, the pre-disposition of a mold for defining the shape of the first side 6 of the printhead 1, as, on the contrary, it is necessary the aforementioned technique in which the entire printhead is made. externally in plastic material. The matrix 19 foreseen in the procedure object of the present invention is, in fact, simply intended to fit and maintain the molded metallic body 2 and, thus, this procedure proves to be simple to be performed in relation to those included in the known technique with a reduction of times and costs. of projection.

In addition, the arrangement of the suction channel 12 and the discharge channel 13 with their respective openings on the same side 17 allows the use of only one carriage 22 for molding the plastic material extract 18. This further simplifies the realization procedure and reduces the relative costs. of production.

Thus, the invention thus described achieves all the preset objectives.

Obviously, the latter may assume in practical embodiment, although in a shape and configuration different from those illustrated above, although to this end it departs from the present scope of protection. In addition, all details may be replaced by technically equivalent elements and the shapes, dimensions and materials used may be other, as required.

Claims (9)

1. Pump head 1 characterized in that it comprises: - a molded metal body 2 provided with a transport surface 14 of a fluid to be pumped, which defines: • at least partially a pumping chamber 3 • at least one channel 12, through which ditofluid to be pumped enters the pumping chamber 3, at least one outlet channel 13, through which dithofluid to be pumped enters the pumping chamber 3, an extract of plastics material 18 of coating , which is substantially printed and exclusively on the transport surface 14. Pump head (1) according to Claim 1, characterized in that said plastic material extract (18) has a thickness of between 2-4 mm, and preferably 3 mm. Pump head (1) according to Claim 1, characterized in that the suction channel (12) and the discharge channel (13) leave the pumping chamber (3) in parallel and flow to one side (7). ) of said molded metal body (2), with a venting hole (4) and a discharge hole (5) disposed near a side molding (17) of said suitably molded metal body (2). Pump head (1) according to Claim 1, characterized in that the molded metal body (2) is made of aluminum. Pump head (1) according to Claim 1, characterized in that said plastic material extract (18) is made of polypropylene. Pump head (1) according to Claim 1, characterized in that such plastic material extract (18) comprises at least one spare element (39), which defines a counter-mold (40) capable of being anchored. solidly on the molded metal body (2). Procedure for making a pump head (1) as defined in claim 1, characterized in that it comprises the following operating phases: - a phase of making said molded metal body (2), substantially in the molded shape of said head (1). - a positioning phase of said molded body (2) within a die (19) and on top of internal projections (35) of the die (19); - a closing phase of said die (19) with; at least one countercurrent (21) having at least one convexity in said pumping chamber (3); and at least one carriage (22) having two parallel punches (26 and 27) which insert into the suction channels (12) said countercurrent (21) and said carriage (22) have the same shape as the die (19), isolating said suitably shaped metal body (2) within a molding chamber in which at least one space ( 23) between said counter current (21) and said car (22), on the one hand, and said the molded body metal (2), on the other hand: an injection phase of said molten plastic material in at least one space (23) with the formation of said plastic material extract (18); plastics material (18) - a phase of removal of said counter current (21) and ditocar (22) for the extraction of said head (1). v A method for making a pump head (1) according to claim 7, characterized in that it comprises the following preheating phases of said molded metal body (2) prior to said positioning phase of said molded metal body (2). Procedure for making a pump head (1) according to claim 7, characterized in that said phase closing of the die (19) is carried out by advancing said carriage (22) over a mold holder (20). by causing the punches (26, 27) to enter into said suction (12) and discharge (13) channels through, respectively, a first opening and a second opening (15,16) made on said side ( 17) of said suitably shaped metal body (2).