EP3757390A1 - Two-part squeezing element for a peristaltic pump and method of making a two-parte squeezing element for a peristaltic pump - Google Patents

Abstract

The present invention relates to a method for producing a squeezing element of a peristaltic pump driven by means of an eccentric. According to the invention it is provided that the pinch element is composed of a carrier and a pinch end, the carrier and pinch end being initially loosely assembled, an effective length of the pinch element then being calibrated to a certain final dimension in a calibration step by relative displacement of the carrier and pinch end, and wherein the carrier and the pinch end are firmly connected to one another in a joining step after calibration.

Description

The present invention relates to a method for producing a squeezing element of a peristaltic pump driven by means of an eccentric. The invention also relates to a two-part squeezing element according to the preamble of independent claim 11.

In the case of a linear peristaltic pump, such as those from DE 102013103223 A1 is known, an elastic hose is deformed in a periodically recurring manner by means of several squeezing elements. The deformation usually has a sinusoidal shape. The squeezing elements of the peristaltic pump are usually designed as squeezing fingers and arranged in a row. The squeezing elements are driven via a common shaft which has several eccentric cams, one of the eccentric cams being assigned to each squeezing finger. A rotation of the shaft is converted into an oscillating linear movement of the pinch fingers by the eccentric cams.

Peristaltic pumps are used, among other things, when exact dosing has to be ensured. Exact dosing is required, for example, when the medium to be conveyed is a drug liquid. The delivery rate of the pump is determined, among other things, by the volume of liquid that is enclosed between two squeezing elements of the pump. In order to ensure exact dosing, the length of the squeezing elements must lie within a very narrow tolerance range.

In the case of the peristaltic pumps known from the prior art, individual parts are therefore usually built in that are manufactured extremely precisely, which means a high manufacturing and testing effort, so that the manufacturing costs are relatively high.

The present invention has set itself the task of specifying a method for producing a squeezing element for a peristaltic pump, by means of which the production effort and the costs associated therewith can be reduced.

The object is achieved by the features of independent claim 1. Accordingly, a method according to the invention is present when the squeezing element is assembled from a carrier and a pinch end, the carrier and pinch end being initially loosely assembled, an effective length of the squeezing element then in a calibration step is calibrated by relative displacement of the carrier and the pinch end to a specific final dimension, and wherein the carrier and the pinch end are firmly connected to one another after the calibration in a joining step.

The method according to the invention offers the advantage that the critical length dimension of the squeezing elements can be achieved with an easy-to-use process, whereby the separately manufactured individual parts used, namely the carrier and the squeezing end, do not have to meet extremely high requirements in terms of dimensional accuracy and can ultimately be manufactured inexpensively .

The pinch element is preferably a pinch finger. The carrier of the squeezing element preferably has a receptacle for the eccentric. However, the squeezing element can also be driven by means of an additional plunger which has the eccentric mount and converts the rotational movement of the rotating shaft of the peristaltic pump into an oscillating linear movement of the squeezing element.

Further advantageous embodiments of the present invention are the subject of the subclaims.

According to a preferred embodiment of the present invention, the carrier or the pinch end is manufactured with a projection which is inserted into a corresponding recess of the other component in order to assemble the carrier and pinch end. This embodiment facilitates the subsequent calibration and also the joining of the two components.

In a particularly preferred embodiment of the present invention, the projection and recess are manufactured in such a way that there is a press fit between projection and recess. This ensures that the two components do not move after the calibration step before they are finally firmly connected to one another. The interference fit is preferably a light interference fit.

Manufacture and assembly are further simplified if, according to a further preferred embodiment of the present invention, the carrier has the projection, the pinch end being manufactured as a cap and slipped onto the projection.

According to a further preferred embodiment of the present invention, the carrier and pinch end are first assembled such that the effective length over the desired final dimension lies, the squeezing element being moved in the calibration step with the aid of the eccentric against a calibration stop which is positioned at an exact distance from an axis of rotation of the eccentric in order to set the final dimension. This considerably simplifies the calibration. The calibration stop is preferably a calibration plate, which is further preferably positioned at a certain distance from the axis of rotation of the eccentric and aligned parallel to the axis. The eccentric is preferably rotated through a full 360 ° during calibration in order to ensure that the squeezing element is brought to the desired effective length.

According to a particularly preferred embodiment of the method according to the invention, several squeezing elements of the peristaltic pump are jointly calibrated to the desired final dimension by placing the squeezing elements on a shaft of the peristaltic pump equipped with appropriate eccentrics and moving them in the calibration step by rotating the shaft against the calibration stop. All squeezing elements of a peristaltic pump are preferably calibrated in this way. This embodiment not only results in a time advantage, since several squeezing elements are calibrated at the same time. The embodiment also has the advantage that the peristaltic pump can be calibrated as a whole, not only compensating for manufacturing inaccuracies of the carrier and pinch ends but also other tolerances, for example the shaft, the corresponding bearings and the eccentric. The squeezing elements are preferably lined up axially with respect to the axis of the shaft. The eccentrics of the shaft can, for example, be simple eccentric cams.

According to a further preferred embodiment of the present invention, the carrier and pinch end are welded to one another in the joining step. This embodiment offers a simple and inexpensive way of finally fixing the two components.

According to a further preferred embodiment of the present invention, the carrier and pinch end are made of plastic. This results in inexpensive production and simple assembly. Polyoxymethylene is particularly preferably used as the plastic.

According to a particularly preferred embodiment of the method according to the invention, the component that has the projection is made of opaque, in particular black plastic, the component with the recess being made of translucent, in particular white plastic, and the two components in the joining step are welded to one another by means of laser light, the laser light at least partially passing through the translucent, in particular white plastic and being absorbed by the opaque, in particular black plastic, in such a way that the material melts and thus welds at a connection point between the two components.

The invention also provides a squeezing element for a peristaltic pump, which is composed of a carrier and a squeezing end. The squeezing element is preferably produced according to the method according to the invention, in particular according to one or more of the above-described embodiments of the method according to the invention.

The invention is explained in more detail below with reference to drawings.

Figur 1:

ein erfindungsgemäßes zweiteiliges Quetschelement in einer perspektivischen Ansicht,

Figur 2:

das zweiteilige Quetschelement aus Figur 1 in einer perspektivischen Explosionsdarstellung,

Figur 3:

einen Längsschnitt durch eine Peristaltikpumpe mit mehreren Quetschelementen gemäß den Figuren 1 und 2, wobei die Quetschelemente zunächst jeweils lose zusammengesetzt sind,

Figur 4:

den Längsschnitt aus Figur 3 nach dem Einsetzen der Peristaltikpumpe in eine Kalibriervorrichtung,

Figur 5:

den Längsschnitt aus Figur 4 nach dem Einstellen der Kalibriervorrichtung,

Figur 6:

den Längsschnitt aus Figur 5 nach Durchführen des Kalibrierschritts, und

Figur 7:

den Längsschnitt aus Figur 6 mit Darstellung des abschließenden Fügeschritts mittels Laser.

Show it:

Figure 1:

a two-part squeezing element according to the invention in a perspective view,

Figure 2:

the two-part squeezing element Figure 1 in a perspective exploded view,

Figure 3:

a longitudinal section through a peristaltic pump with several squeezing elements according to the Figures 1 and 2 , whereby the squeezing elements are initially each loosely assembled,

Figure 4:

the longitudinal section Figure 3 after inserting the peristaltic pump into a calibration device,

Figure 5:

the longitudinal section Figure 4 after setting the calibration device,

Figure 6:

the longitudinal section Figure 5 after performing the calibration step, and

Figure 7:

the longitudinal section Figure 6 with representation of the final joining step using a laser.

For the following statements, the same parts are denoted by the same reference symbols. If a figure contains reference numerals that are not discussed in more detail in the associated description of the figures, reference is made to the preceding or subsequent figure descriptions.

The Figures 1 and 2 show a two-part squeezing element 2 according to the invention for a peristaltic pump. The squeezing element 2 is designed as a squeezing finger and consists of a separately manufactured carrier 4 and a separately manufactured pinch end 5. The carrier 4 has an eccentric receptacle 14 for a rotating eccentric disk or cam. The eccentric receptacle 14 is elongated. In the fully installed state, the squeezing element 2 is received in a linear guide of the peristaltic pump, which allows a linear movement orthogonal to the longitudinal extension of the elongated eccentric receptacle 14, so that a rotation of the eccentric disk is converted into an oscillating linear movement of the squeezing element 2. The carrier 4 also has an upwardly protruding projection 8 on which the pinch end 5, designed as a cap, is placed. For this purpose, the pinch end 5 has a recess 9 into which the projection 8 can be inserted. An effective length of the squeezing element 2 depends on how far the squeezing end 5 is pushed onto the projection 8 of the carrier 4. There is a slight interference fit between the projection 8 and the recess 9 in order to enable the pinch end to be easily positioned and to prevent subsequent slipping.

The method for calibrating the length of the squeezing element 2 is described below with reference to FIG Figures 3 to 7 explained. Figure 3 is an incomplete longitudinal section through a peristaltic pump 1 that has already been equipped with several squeezing elements 2. All squeezing elements 2 are each assembled loosely. The effective length of the squeezing elements is still well above the desired final dimension. The peristaltic pump 1 has a housing 10, only partially shown, in which a rotating shaft 6 of the peristaltic pump is rotatably mounted about an axis 7. The shaft 6 has a total of ten circular eccentric cams 3 lined up axially, each eccentric cam driving one of the squeezing elements 2.

In order to calibrate the effective length of the squeezing elements 2, the incompletely assembled peristaltic pump 1 is inserted into the in Figure 4 The calibration device shown inserted. The calibration device can consist of a lower stop 11 in the form of a stop plate and an upper calibration stop 12, which is also designed as a plate. The housing 10 of the peristaltic pump 1 rests on the lower stop 11. In the next step, the distance between the lower stop 11 and the upper calibration stop 12 is reduced to a certain value, as shown in FIG Figure 5 is shown. Some of the pinch ends 5 are already pushed significantly further onto the associated projections 8 of the carrier 4. The actual calibration now takes place by rotating the shaft a full 360 °. The result of the calibration is in Figure 6 shown. All of the pinch ends 5 became like this pushed far onto the associated projections 8 so that all squeezing elements 2 each reached exactly the same level in their highest position. The perfect positioning achieved in this way then only needs to be fixed. This is preferably done by welding as in Figure 7 shown. Both the carrier 4 and the pinch ends 5 are preferably made of polyoxymethylene, the pinch ends being made of white polyoxymethylene, whereas the carriers are made of black-colored polyoxymethylene. The welding is carried out simply and inexpensively by means of laser radiation 13. The white polyoxymethylene of the pinch ends allows the laser radiation to pass, whereas the black polyoxymethylene of the carrier absorbs the laser radiation. In this way, material melting and thus welding of the two components can be achieved precisely at the interface between the two components.

List of reference symbols

1

Peristaltic pump

2

Squeezing element

3

eccentric

4th

carrier

5

Bruising

6th

wave

7th

axis

8th

head Start

9

Recess

10

casing

11

attack

12th

Calibration stop

13

Laser light

14th

Eccentric mount

Claims (12)

A method for producing a squeezing element (2) of a peristaltic pump (1) driven by an eccentric (3), characterized in that the squeezing element (2) is composed of a carrier (4) and a pinch end (5), the carrier (4) and the pinch end (5) are initially loosely assembled, an effective length of the pinch element (2) then being calibrated to a certain final dimension in a calibration step by relative displacement of the carrier (4) and pinch end (5), and the carrier (4) and the pinch end (5) are firmly connected to one another in a joining step after calibration. Method according to claim 1, characterized in that the carrier (4) or the pinch end (5) is manufactured with a projection (8) which is inserted into a corresponding recess (9) of the other component in order to support the carrier (4) and Assemble the pinch end (5). Method according to Claim 2, characterized in that the projection (8) and recess (9) are manufactured in such a way that there is a press fit between projection (8) and recess (9). Method according to Claim 2 or 3, characterized in that the carrier (4) has the projection (8), the pinch end (5) being manufactured as a cap and being pushed onto the projection (8). Method according to one of Claims 1 to 4, characterized in that the carrier (4) and pinch end (5) are first put together in such a way that the effective length is above the desired final dimension, the pinch element (2) in the calibration step using the eccentric (3 ) is moved against a calibration stop (12) which is positioned at an exact distance from an axis (7) of the eccentric (3) in order to set the final dimension. Method according to Claim 5, characterized in that several squeezing elements (2) of the peristaltic pump (1) are jointly calibrated to the respectively desired final dimension by the squeezing elements (2) being mounted on a shaft (6) of the peristaltic pump (3) equipped with corresponding eccentrics (3). 1) and moved in the calibration step by turning the shaft (6) against the calibration stop (12). Method according to one of Claims 1 to 6, characterized in that the carrier (4) and pinch end (5) are welded to one another in the joining step. Method according to one of Claims 1 to 7, characterized in that the carrier (4) and pinch end (5) are made of plastic. Method according to Claim 8, characterized in that the carrier (4) and pinch end (5) are made from polyoxymethylene. Method according to claim 2, in particular in connection with one of claims 3 to 9, characterized in that the component (4, 5) with the projection (8) is made of opaque, in particular black plastic, the component (4, 5) with the recess (9) is made of translucent, in particular white plastic, and the two components (4, 5) are welded together in the joining step by means of laser light (13), the laser light (13) at least partially breaking the translucent, in particular white plastic happens and is absorbed by the opaque, in particular black plastic in such a way that a material melting and thus welding occurs at a connection point between the two components (4, 5). Squeezing element (2) for a peristaltic pump (1), characterized in that the squeezing element (2) is composed of a carrier (4) and a squeezing end (5). Crimping element (2) according to claim 11, characterized in that the squeezing element (2) is produced according to the method according to one of claims 1 to 10.

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