JPS6329082A - High precision pump - Google Patents

Abstract

PURPOSE:To aim at enhancing the anti-seize ability, anti-wear ability and anti- corrosion ability, by using ultrahard alloy for members adapted to make contact with fluid to be fed, among components of a pump. CONSTITUTION:In a high precision gear pump for feeding under pressure, for example, a polymer having a high viscosity, a high-corrosiveness and a low self-lubricating function, ultrahard alloy which is excellent in heat-resistance, corrosion-resistance and anti-wear ability and has a low thermal expansion coefficient, is used for the inner surfaces of plates 2, 3, tooth surfaces and the like of drive and driven gears 7, 9, an arbor and a stud 8 forming gaps into which fluid to be fed under pressure is liable to enter, and the bearing surfaces of the latter, a coupler and the like, which make into contact with fluid to be fed under pressure, excepting attaching bolts 4, a dowel or the like. This ultrahard alloy is composed of 4-17wt% of bonded phase having as a main component Co and/or Ni containing less than 15wt% of at least one kind of V, Cr, Mo, VC, CrC and MoC, and the remainder of WC and unavoidable impurities. Thus, it is possible to prolong the life of the article.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a precision gear pump, and more specifically, to +M in the chemical and food industries such as textiles, pharmaceuticals, foods, and plastics.
It is used for precision gear pumps with good durability used in manufacturing departments.

[Prior art]

A gear pump pumps fluid by expanding and contracting the space formed between the inner surface of the casing and the tooth surface of the gear that rotates in one direction on the support shaft inside the casing. It has the characteristics of being able to handle a wide range of viscous fluids, withstanding high discharge pressure, and being able to deliver a constant flow rate even when the discharge pressure fluctuates. Since this type of pump has a simple structure and is easy to handle, it is widely used in fields such as the chemical industry for pumping various fluids.

However, gear pumps used in the chemical industry, especially in the manufacturing sector of textiles, medicine, and plastics, are used under harsh operating conditions and undergo significant wear and tear due to the highly corrosive nature and high temperatures of the fluid being pumped.

Therefore, most of the grooved members of gear pumps are corroded or worn to such an extent that the 1σ principle is no longer effective, and in many cases, they are used until such a state is reached and then discarded as is, or become semi-disposable.

However, in recent years there has been an emphasis on saving resources, and there has been an increasing need for car pumps that can be used under harsh conditions. In order to meet this demand, devices in which the drive section is constructed using tool steel, high speed steel, etc., which have high drawing hardness, have been proposed, and many have been put into practical use. Although these gear pumps are quite durable, in some sectors they are difficult to accurately meter sludge-like, non-self-lubricating fluids and semi-liquids at high temperatures that cause significant adhesive wear. In some cases, it may be necessary to transport the product under pressure.

In this case, there is often a problem that the pressurized fluid adheres to or stagnates on the drive section or the sliding section, resulting in corrosion, or the drive section is worn out due to fine solid substances in the pressurized fluid.

Ceramic is a material that can meet this requirement, and is generally well known for its excellent corrosion resistance and wear resistance. A gear pump using this ceramic as a constituent material was proposed in Japanese Patent Application Laid-Open No. 59-583.

has been done. This gear pump has a driving gear and a driven gear made of ceramic, and crowning is applied to the tooth surfaces of these gears.The characteristics of ceramic are exhibited as is, and the pump is resistant to seizure, abrasion, and corrosion. This has the advantage that it is significantly improved.

[Problem that the invention seeks to solve]

However, the above-mentioned gear pump still has problems due to its fragility, which is a drawback of ceramic materials, and the gear itself constituting the drive unit is extremely fragile. Therefore, in order to exhibit the above-mentioned characteristics that incorporate the quality characteristics of ceramics in addition to the performance characteristics originally possessed by gear pumps, there are considerable restrictions on the conditions of use. For example, when trying to obtain a high discharge pressure, a large load is placed on the drive unit, but in such a case, continuous operation for a long time leaves problems with the durability of the tooth surfaces and the gear itself. Therefore, the scope of its use is naturally limited, and further improvements are desired in the future so that it can be put to practical use widely even under various harsh conditions of use.

Taking these circumstances into consideration, the present invention has been developed to provide a measuring device that has extremely good heat resistance, corrosion resistance, and abrasion resistance that can be used under harsh conditions, and has extremely low dimensional deviation due to thermal expansion. The purpose is to provide high precision dentary pumps.

[Means for solving problems]

In order to achieve the above-mentioned object, the means of the present invention is to employ cemented carbide for the members that come into contact with the fluid to be pumped, among the parts constituting the pump.

〔Effect of the invention〕

Since the precision gear pump of the present invention employs cemented carbide for the components that come into contact with the fluid to be pumped, it has excellent corrosion resistance and wear resistance, resulting in a long product life. In addition, because the thermal expansion is small, the volumetric efficiency can be increased by reducing the gaps between each part, and the specified dimensions can be maintained even during operation in high-temperature environments, ensuring high discharge amount accuracy and excellent performance. Effects such as increasing the operating temperature limit due to heat resistance are exhibited.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof.

The precision gear pump of this embodiment is for pumping polymer to textile machinery, and as shown in FIG. 3, an arbor 5 is rotatably supported between the front plate 2 and the back plate 3, and a key 6 is attached to the arbor 5.
°ζ drive gear 7 is fixed via. Further, a stud 8 is provided between the front plate 2 and the bank plate 3 in parallel with the arbor 5.
The stand 8 has a driven gear 9 that meshes with the drive gear 7.
is rotatably supported.

Further, the front end of the arbor 5 projects outward beyond the front plate 2, and a cover 10 is attached to that part, and the cover 10 is rotatably supported by the hub 11. A hub top 12 is provided on the outside of the hub 11, and is fixed integrally with the gear casing 1, front plate 2, and back plate 3 using mounting bolts 4.

The output shaft from the drive source (not shown) is the converter 10.
The arbor 5 can be rotated by being connected to the arbor 5. As shown in FIG. 2, the back plate 3 is provided with an in-left boat 13 and an outlet port 14 for sucking in and discharging fluid. In addition, 1
5 is Dowell. Incidentally, the cover 10 is rotationally driven in the direction of arrow 16 in FIG.

In such a precision gear pump, except for the mounting port 4, the dowel 15, and the knock bottle (not shown), all other members are made of cemented carbide. The target member is in contact with the polymer, which is the fluid to be pumped, at high temperature. That is, the inner surfaces of the front plate 2 and back plate 3, which form spaces that expand and contract in order to pump the fluid to be pumped, and the tooth surfaces of the driving gear 7 and the driven gear 9 are members that come in contact with the fluid to be pumped, but these are the only members that come into contact with the fluid to be pumped. Instead, the fluid to be pumped permeates or reaches not only the arbor 5 and the stud 8 but also the bearing surfaces thereof and even the gaps between the inner and outer surfaces of the cover 10. Polymer has a high viscosity and is used not only for drive members such as the drive gear 7 and driven gear 9, but also for
It is easy to cause corrosion due to adhesion to other parts,
Furthermore, since the self-lubricating function is extremely low, it is easy to cause wear in drive members and the like. Therefore, although expensive, cemented carbide, which has good heat resistance, corrosion resistance, wear resistance, and low coefficient of thermal expansion, is suitable as a constituent material for all parts that come into contact with the polymer.

In general, cemented carbide is an alloy consisting of a hard phase of tungsten carbide WC and a binder phase of Co and/or Ni, or an alloy consisting of a hard phase of WC and a group 4a metal of the periodic table W (Ti, Z
r, )m, 5a group goldff5 (V, Nb, T
ax), alloys consisting of a hard phase with a B-1 type crystal structure consisting of carbides, nitrides of group 6a gold Wb (Cr, Mo, W) or mutual solid solutions thereof and a binder phase of Co and/or Ni. We can separate. When these cemented carbide alloys are used in gear pumps, both the former alloy and the latter alloy exhibit excellent effects, mainly by adjusting the binder phase content of Co and/or Ni. It is. Among these cemented carbide alloys, the former alloy is particularly preferred for application to gear pumps because it has superior strength compared to the latter alloy. Furthermore, among the former alloys, cemented carbide, which consists of 4 to 17 mm% of a binder phase mainly composed of Co and/or Ni, and the remainder of tungsten carbide and unavoidable impurities, has excellent wear resistance and strength. Therefore, it is preferable to use it for float pumps. In addition, where special corrosion resistance is required, such as in gear pumps for chemicals, the bonding phase may be vanadium, chromium,
The use of a cemented carbide consisting of at least 15 weight percent of at least one selected from molybdenum, vanadium carbide, chromium carbide, and molybdenum carbide, and the remainder Co and/or Ni, exhibits excellent effects and is effective for gear pumps. This is preferable because the life span is improved.

The compact gear pump of the present invention can be manufactured by grinding, polishing, or other processing as necessary on a cemented carbide obtained by conventional powder metallurgy. The cemented carbide is further subjected to hot isostatic pressing (H(P) treatment in a nitrogen gas or inert gas atmosphere at a pressure of 1300 bar or higher and a temperature of 1350°C or higher, followed by grinding and polishing as necessary. It is preferable to fabricate the material by such processing because the strength is significantly improved.

As mentioned above, the method of manufacturing cemented carbide that undergoes HTP treatment improves product yield, improves toughness, reduces dimensional variations, and increases reliability. It recognized. Therefore, recently, cemented carbide manufacturers have begun to adopt this HIP treatment technology. Furthermore, it has already been clarified that cemented carbide has excellent corrosion resistance from the results of immersion tests conducted with various highly corrosive liquids. In particular, the composition of cemented carbide can be adjusted, and it can be made to have good corrosion resistance even against highly corrosive liquids. And since cemented carbide has a very small coefficient of thermal expansion,
Even though the temperature differs significantly between manufacturing and operation, it is perfectly suited as a constituent material for precision gear pumps that require micron-level clearance accuracy under high-temperature operating conditions. Based on the above, drive members such as the drive gear 7 and the driven gear 9 are manufactured using the HIP process described above, subjected to NC processing for the preliminary processing, and then processed using a diamond grinding wheel. A finishing process is adopted. Other non-driving members may be made of cemented carbide manufactured by a conventional manufacturing method without any particular HIP treatment.

Precision gear pumps made of these materials always maintain high discharge volume accuracy regardless of temperature changes, and have high corrosion resistance, abrasion resistance, heat resistance, impact resistance, etc. . Therefore, chemical industry tears, etc.
Not only can it be used for general pumping of high-temperature, highly viscous, and corrosive fluids, but even if the fluid to be pumped has low self-lubricating properties, it can slide smoothly and cause less wear. It exhibits excellent properties even in applications such as measuring that require high accuracy in discharge amount, and can be expected to have good durability and excellent performance when used widely under harsh usage conditions.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the central part of an embodiment of the precision gear pump of the present invention, FIG. 2 is a rear view of the gear pump, and FIG. 3 is a front view of the gear pump. Components in contact with the pressurized fluid [1- Gear casing, 2-
・-Front plate, 3・-Back plate, 5・-
Arbor, 6--key, 7--driving gear, 8-stud, 9--driven gear, 10--cover, 11--
Hub, 12 - hub top].

Claims (3)

[Claims] (1) A precision gear pump characterized in that among the parts that make up the pump, the members that come into contact with the fluid to be pumped are made of cemented carbide. (2) The cemented carbide comprises 4 to 17% by weight of a binder phase mainly composed of Co and/or Ni, and the remaining tungsten carbide and unavoidable impurities. Precision gear pump as described. (3) The binder phase contains at least 15% by weight of at least one selected from vanadium, chromium, molybdenum, vanadium carbide, chromium carbide, and molybdenum carbide, and the remaining carbon
The precision gear pump according to claim 2, characterized in that it is made of O and/or Ni.